Characteristics of Pickering emulsions stabilized by microgel particles of five different plant proteins and their application

Pickering emulsions stabilized by protein particles are of great interest for use in real food systems. This study was to investigate the properties of microgel particles prepared from different plant proteins, i.e., soybean protein isolate (SPI), pea protein isolate (PPI), mung bean protein isolate (MPI), chia seed protein isolate (CSPI), and chickpea protein isolate (CPI). MPI protein particles had most desirable Pickering emulsion forming ability. The particles of SPI and PPI had similar particle size (316.23 nm and 294.80 nm) and surface hydrophobicity (2238.40 and 2001.13) and emulsion forming ability, while the CSPI and CPI particle stabilized emulsions had the least desirable properties. The MPI and PPI particle stabilized Pickering emulsions produced better quality ice cream than the one produced by SPI particle-stabilized emulsions. These findings provide insight into the properties of Pickering emulsions stabilized by different plant protein particles and help expand their application in emulsions and ice cream.

Ice cream with sucralose, stevioside, and erythritol as sugar substitutes: Sensory profile and customer preference

Sugar-free food has been gaining popularity because of low-calorie content. But sugar replacement by high-intensity sweeteners can negatively affect sensory. In this study, the effect of the addition of sucralose (Suc), stevioside (Ste), and erythritol (Ery) as sugar substitutes on the sensory profile and overall acceptance of ice cream were evaluated by penalty analysis (PA) based on the check-all-that apply (CATA) method, with those of the partial least squares (PLS) regression. Twelve sweetening agents of ice cream samples were presented to 106 consumers who answered on an overall liking question using the 15-point hedonic scale and a CATA question with 32 attributes that described the sensory characteristics of ice cream. The results showed that mixed sweeteners (60%Suc+20%Ste+20%Ery or 60%Suc+10%Ste+30%Ery) can present an advantageous performance when used separately, and making ice cream similar to that of sucrose (Sac) added. Adding Suc, Ste, and Ery to ice cream hardly felt bitterness, astringency, and chemical-like sensations of the sweetening agent. The significant difference between different sweeteners is the intensity and speed of sweetness. Developing combination of high-potency sweeteners that can make sweetness appear quickly could open up new ways to design sugar-free ice cream.

Thermally treated peanut oil bodies as a fat replacer for ice cream: Physicochemical and rheological properties

This study investigates the potential use of peanut oil bodies as a fat replacer in ice cream. We explored the effects of different treatments, fresh (FOB), heated (HOB), and roasted (ROB) peanut oil bodies on ice cream preparation. Heat treatment altered the intrinsic protein profile on the oil bodies' surface, subsequently influencing the ice cream's properties. Notably, heat treatment increases the oil bodies' size and the absolute value of ζ-potential. The rheological analysis provided information about void volumes, indicating easier air incorporation during whipping for ROB (72 to 300 nm) than FOB (107 to 55 nm). ROB ice cream displays a high overrun and a lower melting rate compared to FOB ice cream. Moreover, thermal treatment reduces the beany flavors, n-hexanal, and 2-pentenylfuran. Overall, this study reveals peanut oil bodies as a promising platform for rational design of fat-substituted plant-based ice creams.

Determination of Cannabinoids in Cannabis sativa Oil and Infused Ice Cream by LC-DAD Method

BACKGROUND

Cannabis sativa is known to produce a class of terpenophenolic compounds named cannabinoids. The two main ones are cannabidiol (CBD) and tetrahydrocannabinol (THC), which have therapeutic properties. In the development of cannabis-based preparations, it is important to have suitable analytical methods for the analysis of the principal cannabinoids.

OBJECTIVE

This study aimed to develop and validate a simple and rapid HPLC method with photodiode array detection for determination of CBD and THC in Cannabis sativa oil extract and infused ice cream, including a stability study.

METHOD

Chromatographic separation of CBD and THC was performed with a C18 column, with a mobile phase consisting of acetonitrile and water with formic acid (80 + 20 v/v) in isocratic elution mode, with detection at 208 nm for CBD and 280 nm for THC and 1.0 mL/min flow rate.

RESULTS

The method was linear over a range of 1-5 µg/mL for CBD, and 20-100 µg/mL for THC; the relative standard deviation was <3.6%, the recovery ranged between 98.8 and 102.5% for oil and between 84 and 94% for ice cream, QL was 0.33 µg/mL for CBD and 2.30 µg/mL for THC, and the assay demonstrated adequate selectivity. CBD and THC were stable for at least 28 days under light protection at 22°C, 4°C, and -20°C in the oil and for at least 60 days at -20°C in the ice cream.

CONCLUSIONS

The results showed that the method was suitable for quantitative determination of CBD and THC in Cannabis sativa oil extract and infused ice cream, and it is useful for quality control purposes.

HIGHLIGHTS

The method is simple and fast, and it is useful for the quality control of a new product corresponding to an ice cream based on a Cannabis sativa oil extract.

Production and functional evaluation of nonfat dry milk with whey proteins as fibrils

Commercial manufacturing of dairy products involves the addition of dairy ingredients (such as nonfat dry milk and milk protein concentrates), as well as nondairy additives (such as gums, stabilizers, emulsifiers, and texture modifiers) to get the best product appearance, maintain the product quality, and extend shelf life. Though these nondairy additives are not harmful, consumers do not prefer them in dairy food formulations. Therefore, the dairy industry is working on improving the inherent functionality of dairy ingredients using different processes. Recently, fibrillation emerged as a new technique to convert globular proteins such as whey proteins into fibrils, which provide enhanced viscosity, foaming, and emulsification capacity. Therefore, skim milk was subjected to microfiltration followed by ultrafiltration of microfiltration permeate to fractionate whey proteins. Then, whey proteins were selectively fibrillated and mixed back with other streams of microfiltration and ultrafiltration to get fibrillated skim milk. Fibrillated skim milk was spray-dried to get fibrillated nonfat dry milk (NDM). Visible whey protein fibrils were observed in reconstituted fibrillated NDM, which showed survival of fibrils in fibrillated NDM. Fibrillated NDM showed significantly higher viscosity than control NDM. Fibrillated NDM also showed higher emulsification capacity, foaming capacity, and stability than the control NDM but lower gel strength. Considering the improved functionality of fibrillated NDM, they can be used in product formulations such as ice cream mix, where the thickening of a solution, good emulsification, and foaming properties are required.

The impact of glycerol monostearate's similarity to fats and fatty acid composition of fats on fat crystallization, destabilization, and texture properties of ice cream

BACKGROUND

Fat significantly affects the properties of ice cream. Prior studies have investigated the correlation between fat crystallization, fat destabilization, and ice cream quality. However, the role of fatty acid composition, the similarity between fat and emulsifier in these characteristics, and their impact on final product quality remains unclear.

RESULTS

To investigate the influence of the fatty acid composition of fats, as well as their similarity to glycerol monostearate (GMS), on fat crystallization and destabilization during the aging and freezing stages, ice creams were formulated using a combination of two types of fats (coconut oil and palm olein) in five different ratios. In oil phases, decreased saturation of fatty acids (from 93.38% to 46.69%) and increased similarity to GMS (from 11.96% to 46.01%) caused a reduction in the maximum solid fat content. Moreover, the rise in unsaturated long-chain fatty acids (from 34.61% to 99.57%) and similarity to GMS enhanced the formation of rare and coarse fat crystals, leading to a sparse crystalline network. This, in turn, reduced the crystallization rate and the stiffness of the fat in emulsions. Assuming consistent overrun across all ice creams, the enhanced interactions between fat globules in ice cream improved its hardness, melting properties, and shrinkage.

CONCLUSION

The crystalline properties of fat in emulsions were influenced by oil phases, impacting fat destabilization and ultimately enhancing the quality of ice cream. The present study offers valuable insights for the optimization of fat and monoglyceride fatty acid ester selection, with the potential to improve ice cream quality. © 2023 Society of Chemical Industry.

Pea (Pisum sativum L.) pod powder as a potential enhancer of probiotic Enterococcus faecium M74 in ice cream and its physicochemical, structural, and sensory effects

BACKGROUND

In this study, pea (Pisum sativum L.) pod powder (PPP) was incorporated (1% and 3% w/w) into a probiotic ice cream formulation containing Enterococcus faecium M74 to investigate the potential effect of PPP on the probiotic survivability in the ice cream throughout 60 days of frozen storage. Moreover, the produced symbiotic ice creams were evaluated for their physiochemical properties, stability, and sensory acceptability.

RESULTS

Incorporation of PPP into ice cream caused significantly (P < 0.05) increased protein and ash content and lower pH values. Besides that, the addition of PPP resulted in ice creams with higher hardness and lower overrun. A significant diminishing was observed in the melting rates of the ice creams as the percentage of PPP increased and storage time progressed. Ice cream with PPP presented lower lightness and higher greenness and yellowness compared with control. All ice creams had viable counts of E. faecium M74 of ≥6 log cfu g-1 during storage and provided the number of viable cells that the probiotic product should contain. On day 60, the viability of E. faecium M74 in ice cream containing 1% PPP (7.64 ± 0.02) was higher than the control (7.28 ± 0.00). Sensory analyses revealed that there was no statistical difference in ice cream with 1% PPP and the control without PPP in terms of general acceptability.

CONCLUSION

These results suggest that pea pods, which is a waste product of the pea industry and obtained at zero cost, could be used as a potential prebiotic and an agent to improve technological properties of dairy products. © 2022 Society of Chemical Industry.

Occurrence of Perfluoroalkyl and Polyfluoroalkyl Substances in Ice Cream, Instant Noodles, and Bubble Tea

Food consumption is a significant exposure route to perfluoroalkyl and polyfluoroalkyl substances (PFAS). The concentrations of 27 PFAS in fast food were determined by ultrahigh-performance liquid chromatography-high resolution mass spectrometry. In ice cream, instant noodles, and bubble tea, some PFAS were detected, among which perfluorooctanoic acid, perfluoro-n-butanoic acid, and 6:2 polyfluoroalkyl phosphate monoester showed relatively high concentrations. PFAS migrating from bubble tea cups to the food simulant of 50% ethanol aqueous solution showed a difference compared with those migrating into bubble tea matrices. The migration of 27 PFAS to bubble tea samples indicated that long storage time increased PFAS levels (up to 4.8 times) and so did high storage temperature (up to 7.3 times). The hazard ratio, defined as the ratio of the estimated daily intake and the reference dose, was calculated, and it suggests that the total PFAS exposure risk due to consumption of bubble tea should be of concern.

The Health-Promoting and Sensory Properties of Tropical Fruit Sorbets with Inulin

Inulin is a popular prebiotic that is often used in the production of ice cream, mainly to improve its consistency. It also reduces the hardness of ice cream, as well as improving the ice cream’s organoleptic characteristics. Inulin can also improve the texture of sorbets, which are gaining popularity as an alternative to milk-based ice cream. Sorbets can be an excellent source of natural vitamins and antioxidants. The aim of this study was to evaluate the effect of the addition of inulin on the sensory characteristics and health-promoting value of avocado, kiwi, honey melon, yellow melon and mango sorbets. Three types of sorbets were made—two with inulin (2% and 5% wt.) and the other without—using fresh fruit with the addition of water, sucrose and lemon juice. Both the type of fruit and the addition of inulin influenced the sorbet mixture viscosity, the content of polyphenols, vitamin C, acidity, ability to scavenge free radicals using DPPH reagent, melting resistance, overrun and sensory evaluation of the tested sorbets (all p < 0.05). The addition of inulin had no impact on the color of the tested sorbets, only the type of fruit influenced this feature. In the sensory evaluation, the mango sorbets were rated the best and the avocado sorbets were rated the worst. Sorbets can be a good source of antioxidant compounds. The tested fruits sorbets had different levels of polyphenol content and the ability to scavenge free radicals. Kiwi sorbet had the highest antioxidant potential among the tested fruits. The obtained ability to catch free radicals and the content of polyphenols proved the beneficial effect of sorbets, particularly as a valuable source of antioxidants. The addition of inulin improved the meltability, which may indicate the effect of inulin on the consistency. Further research should focus on making sorbets only from natural ingredients and comparing their health-promoting quality with the ready-made sorbets that are available on the market, which are made from ready-made ice cream mixes.

Optimized pulsed electric field-assisted extraction of biosurfactants from Chubak (Acanthophyllum squarrosum) root and application in ice cream

BACKGROUND

In this study, a face-centered central composite design was applied to optimize pulsed electric field parameters (voltage: 1, 4, 7 kV cm^-1 ; pulse number: 10, 65, 120) for the extraction of natural saponins from Chubak root. Data analysis showed that increasing the voltage from 1 to 4 kV cm^-1 and pulse number from 10 to 65 increased foaming ability (FA) and emulsion stability, and decreased foam density (FD), foam stability (FS) and lightness, due to the improved extraction of saponins.

RESULTS

Whereas, an opposite trend was observed for FA, FD and FS on increasing the voltage from 4 to 7 kV cm^-1 as a result of more impurities being extracted. Furthermore, the Chubak root extract (CRE) (0, 1.5, 3.0 and 4.5 g kg^-1 ) obtained under the optimized conditions (voltage of 6.4 kV cm^-1 and pulse number of 80) was used in ice cream formulation because of its ability to reduce surface tension. Based on the results, the samples containing higher amounts of CRE showed higher viscosity, consistency coefficient, overrun, melting resistance and creaminess, as well as lower values of flow behavior index, hardness, adhesiveness, coarseness and coldness. This could be related to the increased water retention, improved whipping ability, greater fat destabilization and smaller ice crystals. Although more bitterness was perceived as a result of an increase in the level of CRE, it had no negative effect on the overall acceptance assessed by trained sensory panelists.

CONCLUSIONS

The results of this study briefly support the conclusion that CRE has a very high potential for use as a foaming, emulsifying and stabilizing agent to improve the quality of ice cream. © 2020 Society of Chemical Industry.

Synbiotic sheep milk ice cream reduces chemically induced mouse colon carcinogenesis

Sheep dairy products containing prebiotic and probiotic ingredients may have health-promoting properties. Thus, this study evaluated the effects of sheep milk ice cream [conventional full-fat (CONV), full-fat enriched with probiotic (PROB, 100 mg % wt/wt of Lacticaseibacillus casei 01), or nonfat synbiotic (SYNB, Lacticaseibacillus casei 01 and inulin, 10% wt/wt)] on carcinogen-induced colonic crypt cytotoxicity and premalignant lesion development. Male Swiss mice received 2 doses of colon carcinogen azoxymethane (AOM, 15 mg/kg of body weight) at wk 3 and 4. Two weeks before and during AOM administrations (4 wk) mice were treated with CONV, PROB, or SYNB by gavage (10 mL/kg). Mice were euthanized at wk 4 or 25 (n = 5 or 10 mice/group, respectively). At wk 4, a significant reduction in micronucleated colonocytes was observed in PROB and SYNB groups, and a significant decrease in both p53 expression and apoptosis indexes in colonic crypts was observed in SYNB group. At wk 25, both PROB and SYNB interventions reduced the mean number of colonic premalignant lesions. However, only SYNB group showed lower incidence and number of high-grade premalignant lesions in the colonic mucosa. These findings indicate that PROB or SYNB sheep milk ice cream, especially SYNB intervention, can reduce chemically induced mouse colon carcinogenesis.

Food Fraud: A Simple and Efficient LC-MS/MS Approach for Peptide-Based Food Authentication

Food fraud includes the addition of inferior components or the substitution of substances. Besides being of economic concern, this might furthermore pose a health risk for consumers. Therefore, the detection of replacements is of high importance. For the identification of species, in recent years proteomic methods gained more and more importance. In this work, an easy and efficient approach of targeted peptide analytics for revealing food fraud is presented. One of the most common workflows for protein analytics was improved by the application of urease to hydrolyze the urea in the extraction buffer; therefore, no further cleanup is required. By considering only selected compounds and the use of open-source databases for the selection of the target peptides for the adoption of the analytical methods, no time-consuming basic research is required. For the detection of the substitutes, it is not necessary to know the absolute concentration of the component. In these cases, the calculation of the proportion of a species in relation to the total content of all analyzed compounds is sufficient.

Peptidome profiles and bioactivity elucidation of buffalo-milk dairy products after gastrointestinal digestion

Buffalo milk is highly appreciated for its nutritive properties and highly employed in dairy products, despite this the release of bioactive peptides has not been investigated thoroughly. The aim of this work was to characterize in detail the bioaccesible peptides from buffalo-milk dairy products. Six products were subjected to in vitro simulated gastrointestinal digestion and then analyzed by LC-HRMS. The identified peptides were 165 in Yoghurt, 152 in Scamorza, 146 in Mozzarella, 136 in Grana and Ricotta, 120 in Ice Cream samples, belonging to both buffalo caseins (α_s1-, β-, k-CN) and whey proteins (α-LA, β-LG). The identified peptide sequences were subjected to a database driven bioactivity search. Results highlighted a wide range of potential bioactive peptides, including antihypertensive, immunomodulatory, antimicrobial, antidiabetic, anticancer and antioxidant activity. These data evidence the content of healthy peptides released from buffalo-milk dairy products and suggest that the specific technological process influence their bioaccessibility.

Omega-3 fatty acids and oxidative stability of ice cream supplemented with olein fraction of chia (Salvia hispanica L.) oil

BACKGROUND

Chia (Salvia hispanica L.) has been regarded as good source of polyunsaturated omega-3 fatty acids with cardiac, hepatic, hypotensive, antiallergic and antidiabetic role. Concentration of omega-3 fatty acids in chia oil can be enhanced by fractionation. Olein/low melting fraction of chia oil has higher concentration of omega-3 fatty acids. Therefore, main objective of current investigation was determination of various concentration effect of olein fraction of chia oil on omega-3 fatty acids, oxidative stability and sensory characteristics of ice cream.

METHODS

Ice cream samples were prepared by partially replacing the milk fat with olein fraction of chia oil at 5, 10, 15 and 20% concentrations (T1, T2, T3 and T4), respectively. Ice cream prepared from 100% milk fat was kept as control. Ice cream samples stored at -18 °C for 60 days were analysed at 0, 30 and 60 days of the storage period. Fatty acid profile, total phenolic contents, total flavonoids, free fatty acids, peroxide value, anisidine value and sensory characteristics of ice cream samples was studied.

RESULTS

Concentration of α-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid in T4 was 13.24, 0.58, 0.42 and 0.31%, respectively. Total phenolic contents of control, T1, T2, T3 and T4 were recorded 0.12, 1.65, 3.17, 5.19 and 7.48 mg GAE/mL, respectively. Total flavonoid content of control, T1, T2, T3 and T4 were found 0.08, 0.64, 1.87, 3.16 and 4.29 mg Quercetin Equivalent/mL. 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity of control, T1, T2, T3 and T4 was noted 5.61, 17.43, 36.84, 51.17 and 74.91%, respectively. After 60 days of storage period, the highest peroxide value of 1.84 (MeqO2/kg) was observed in T4, which was much less than allowable limit of 10 (MeqO2/kg). Flavour score was non-significant after 30 days of storage period.

CONCLUSIONS

Supplementation of ice cream with olein fraction of chia oil enhanced the concentration of omega-3 fatty acids and improved the antioxidant perspectives of ice cream. These results suggest that omega-3 fatty acids and antioxidant characteristics of ice cream may be improved with olein fraction of chia oil for discerning consumers.

Functionality of kumquat (Fortunella margarita) in the production of fruity ice cream

BACKGROUND

The aim of this study was to investigate the effect of kumquat (Fortunella margarita) on the quality characteristics of ice cream. Kumquat paste (KP) was added to an ice cream mix at four concentrations, 0 (control), 5, 10 and 15% (w/w), for ice cream production.

RESULTS

The increment of KP level caused an increase in acidity, vitamin C content, b* value and overrun value compared with the control ice cream. The apparent viscosity of samples decreased with the addition of KP at concentrations of 5 and 10% compared with the control. Results indicated that lyophilized water extract of KP (LKE) contained remarkable phenolic compounds. It was observed that LKE exhibited moderate in vitro antioxidant capacity. KP enhanced the color, flavor, vitamin C content and Mg and K contents of the ice cream. The addition of KP positively affected the sensory properties.

CONCLUSION

KP may be used as a suitable source of natural color and flavor agent in ice cream production. KP enhanced the vitamin C content and Mg and K contents of ice cream and improved its sensory properties.

Validation of the AgraStrip® gluten G12 test kit

Romer Labs , Inc. developed an immunochromatographic lateral flow assay for the qualitative detection of gluten in raw ingredients, processed foods, finished food products, and environmental surfaces, using the G12 antibody developed by Belén Morón. The G12 antibody targets a 33-mer peptide which is resistant to enzymatic digestion and heat denatiuration, as well as being the fragment of the gliadin protein.to which celiac disease sufferers react, making it a reliable analytical marker. This study was performed to validate the AgraStrip® GlutenG12 assay method under the guidance of the AOAC Peiformance Tested MethodsSM (PTM) program against AOAC Official Method of AnalysisSM 2012.01 in rice flour, bread, cookie, ice cream, and chocolate matrixes spiked with either purified gliadin or wheat gluten standard at 0, 3, 8, 15, and 25 ppm concentrations and tested at the 5, 10, and 20 ppm assay thresholds, as well as on, environmental surfaces. Stability, robustness, variation, and lot consistency studies were performed by spiking wheat gluten into a rice flour matrix at 0 and 15 ppm concentrations. The AgraStrip Gluten G12 assay was rigorously evaluated during this study and demonstrates its suitability as an AOAC PTM-certified gluten detection method.

Chemical properties and sensory quality of ice cream fortified with fish protein

BACKGROUND

Fish protein powder is a functional ingredient that can be used for enhancing the nutritional value of food products. In this study the effect of fortification with different levels of fish protein powder (FP) on chemical properties and sensory quality of Persian ice cream with 0, 30 and 50 g kg(-1) FP during storage at - 18 °C for 4 months was investigated.

RESULTS

Ice creams fortified with 50 and 30 g kg(-1) FP had significantly higher protein and solid-non-fat content than ice cream with 0% FP or 83, 69 and 51 g kg(-1) protein and 215, 204 and 181 g kg(-1) solid non-fat, respectively. All products had the same levels of fat, lactose, acidity and pH. They had similar sensory quality after production except for colour, but sensory properties of fortified samples changed significantly after 2 months of storage. Colour faded, cohesiveness decreased, sandiness/coarseness increased, sweetness decreased and fish flavour and off-odour increased. The control ice cream scored highest for additives odour and flavour.

CONCLUSION

Development of ice cream fortified with fish protein powder could be an effective way to enhance nutritional and functional value of ice cream. But studies on storage stability, consumers' acceptance and attitudes are recommended if companies are planning to do so.

Ice-structuring peptides derived from bovine collagen

Antifreeze proteins belonging to structurally diverse families of genetically coded proteins from several living organisms have been isolated and characterized in the past. This paper reports that collagen peptides of a certain molecular size range derived from Alcalase hydrolysis of bovine gelatin are able to inhibit recrystallization of ice in frozen ice cream mix as well as in frozen sucrose solutions in a manner similar to natural antifreeze proteins. The optimum conditions for producing such ice-structuring peptides (ISP) were hydrolysis at pH 9.0 for 30 min at 45 degrees C and an Alcalase-to-gelatin ratio of 0.176 unit per gram of gelatin. The collagen peptides were fractionated on size exclusion (Sephadex G-50) and ion exchange (sulfopropyl-Sephadex C-25) columns, and the molecular mass distribution of the ice-structuring peptide fractions was determined by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry. The collagen peptide fractions in the molecular mass range of 600-2700 Da inhibited ice recrystallization in a supercooled ice cream mix and in concentrated sucrose solutions. The cationic collagen peptides within this fraction with molecular mass in the range of 1600-2400 Da were more effective than the anionic peptides in inhibiting ice crystal growth.

Evaluation of rice flour for use in vanilla ice cream

The effects of varying concentrations (2, 4, and 6%) of 2 types of rice flours (RF 1 and RF 2) on the physicochemical properties and sensory characteristics of vanilla ice cream samples were assessed at different fat levels (0, 4, and 10%) and storage conditions (control vs. heat-shocked). Fat and total solids were measured as well as hardness, viscosity, and melting rate. Eight trained panelists conducted descriptive sensory analyses of the samples at 0 and 7 wk. The 2% rice flour level and to a certain extent the 4% usage level generally improved texture while affecting to a lesser extent the flavor characteristics of the samples compared with the control. The RF 2 generally had a more significant effect than RF 1, especially on the texture attributes. Although the rice flour reduced the negative impact of temperature abuse on textural properties, the samples still deteriorated in textural properties (more icy) under temperature abuse conditions. In addition, rice starch does lower perceived sweetness and can have a "flour flavor" at high usage levels. The use of rice flour appears to be most advantageous for low fat ice cream samples.

Aflatoxin M1 contamination of milk and ice cream in Abeokuta and Odeda local governments of Ogun State, Nigeria

A survey was undertaken to determine the aflatoxin M(1) contamination of milk and some locally produced dairy products in Abeokuta and Odeda local governments of Ogun State, Nigeria. Samples of human and cow milk, yoghurt, "wara", ice cream and "nono" were collected randomly within the local governments and analysed for aflatoxin M(1) using the two-dimensional TLC. Aflatoxin M(1) contamination in the range of 2.04-4.00 microg l(-1) was noticed only in milk and ice cream. In particular, samples of human milk, cow milk and ice cream recorded high scores of 4.0 microg l(-1), 2.04 microg l(-1) and 2.23 microg l(-1), respectively in Abeokuta local governments and a score of 4.0 microg l(-1) for cow milk in Odeda local government. This indicates a high level contamination in the local governments since the weighted mean concentration of aflatoxin M1 in milk for African diet is 0.002 microg l(-1). Therefore the concentration of AFB1 in feeds which is transformed to AFM1 in milk should be reduced by good manufacturing and good storage practices. Furthermore, there is need for stringent quality control during processing and distribution of these products.

ESR/spin probe study of ice cream

Spin probes based on the 1,1,3,3-tetramethylisoindolin-2-yl structure have been used, in conjunction with electron spin resonance spectroscopy (ESR), to study the physical changes occurring in ice cream during freezing and melting. The ESR measurements allowed the rotational correlation times, tau(B), of the spin probes to be determined. Two probes were used together in a given sample of ice cream, namely, 1,1,3,3-tetramethylisoindolin-2-yl (TMIO), which samples the fat phase, and the sodium salt of 1,1,3,3-tetramethylisoindolin-2-yloxyl-5-sulfonate (NaTMIOS), which samples the aqueous phase. Data from the TMIO probe showed that when ice cream is cooled, the fat phase is a mixture of solid and liquid fat until a temperature of approximately -60 degrees C is reached. The water-soluble probe NaTMIOS showed that the aqueous phase changes completely from liquid to solid within 1 degrees C of -18 degrees C. On cooling further to -24.7 degrees C and then allowing it to warm to +25.0 degrees C, the rotational correlation times of the NaTMIOS were slow to recover to their previous values. For the lipid phase, tau(B)(298) was found to be 65.7 +/- 2.0 ps and the corresponding activation enthalpy, DeltaH, was 32.5 +/- 0.9 kJ mol(-)(1): These values are typical of those expected to be found in the type of fat used to make ice cream. The water phase gave corresponding values of 32.2 +/- 0.5 ps and 24.5 +/- 0.4 kJ mol(-)(1) values, which are those expected for a sucrose concentration of 24%.

Increasing the Protein Content of Ice Cream

Vanilla ice cream was made with a mix composition of 10.5% milk fat, 10.5% milk SNF, 12% beet sugar, and 4% corn syrup solids. None of the batches made contained stabilizer or emulsifier. The control (treatment 1) contained 3.78% protein. Treatments 2 and 5 contained 30% more protein, treatments 3 and 6 contained 60% more protein, and treatments 4 and 7 contained 90% more protein compared with treatment 1 by addition of whey protein concentrate or milk protein concentrate powders, respectively. In all treatments, levels of milk fat, milk SNF, beet sugar, and corn syrup solids were kept constant at 37% total solids. Mix protein content for treatment 1 was 3.78%, treatment 2 was 4.90%, treatment 5 was 4.91%, treatments 3 and 6 were 6.05%, and treatments 4 and 7 were 7.18%. This represented a 29.89, 60.05, 89.95, 29.63, 60.05, and 89.95% increase in protein for treatment 2 through treatment 7 compared with treatment 1, respectively. Milk protein level influenced ice crystal size; with increased protein, the ice crystal size was favorably reduced in treatments 2, 4, and 5 and was similar in treatments 3, 6, and 7 compared with treatment 1. At 1 wk postmanufacture, overall texture acceptance for all treatments was more desirable compared with treatment 1. When evaluating all parameters, treatment 2 with added whey protein concentrate and treatments 5 and 6 with added milk protein concentrate were similar or improved compared with treatment 1. It is possible to produce acceptable ice cream with higher levels of protein.

Viability of human-derived probiotic lactobacilli in ice cream produced with sucrose and aspartame

A mixture of human-derived probiotic strains of Lactobacillus acidophilus, L. agilis and L. rhamnosus was used as a probiotic culture in ice cream manufacture. Viability and survival of these probiotic cultures were investigated in two different ice cream formulations. Ice cream with sucrose and ice cream with aspartame were prepared and each of these was divided into two subgroups: one with direct addition of the probiotic culture and one with milk fermented by the same probiotic culture. Ice cream samples were stored at -20 degrees C for 6 months and the survival rate of cultures were determined monthly. Probiotic cultures underwent tests for resistance to bile salts, antibiotics, acidic conditions; they were found to be highly resistant to such challenges. Chemical analysis of ice cream samples, such as determination of acidity, pH and solid matter, was also performed. The probiotic cultures remained unchanged in ice cream stored for up to 6 months regardless of the sweeteners used. Using probiotic cultures in ice cream mixes did not alter the characteristics of the product.

Ice recrystallization inhibition in ice cream as affected by ice structuring proteins from winter wheat grass

Ice recrystallization in quiescently frozen sucrose solutions that contained some of the ingredients commonly found in ice cream and in ice cream manufactured under commercial conditions, with or without ice structuring proteins (ISP) from cold-acclimated winter wheat grass extract (AWWE), was assessed by bright field microscopy. In sucrose solutions, critical differences in moisture content, viscosity, ionic strength, and other properties derived from the presence of other ingredients (skim milk powder, corn syrup solids, locust bean gum) caused a reduction in ice crystal growth. Significant ISP activity in retarding ice crystal growth was observed in all solutions (44% for the most complex mix) containing 0.13% total protein from AWWE. In heat-shocked ice cream, ice recrystallization rates were significantly reduced 40 and 46% with the addition of 0.0025 and 0.0037% total protein from AWWE. The ISP activity in ice cream was not hindered by its inclusion in mix prior to pasteurization. A synergistic effect between ISP and stabilizer was observed, as ISP activity was reduced in the absence of stabilizer in ice cream formulations. A remarkably smoother texture for ice creams containing ISP after heat-shock storage was evident by sensory evaluation. The efficiency of ISP from AWWE in controlling ice crystal growth in ice cream has been demonstrated.

Solid-state characterization of spray-dried ice cream mixes

The main physicochemical properties of spray-dried ice cream mixes (i.e. surface composition, wettability, flowability and microstructure) were analyzed. Emulsions contained 19-44% milk fat on a dry basis and included mixes with no added emulsifier and/or sucrose. The time necessary for complete wetting of the powders correlated with the amount of surface free-fat measured by means of solvent extraction. Non-micellar casein (sodium caseinate) showed to be a better co-encapsulant than micellar casein (skim milk) as demonstrated by surface fat coverage measured by electron spectroscopy for chemical analysis (ESCA). Emulsifiers influenced the fat surface composition of the powders by reducing the amount of surface protein due to their lower interfacial tension. Surface fat caused an initial overestimation of the particle size of the powders due to fat-related caking. Powders showed no flow before and after surface fat extraction which was attributed to fat-related caking and very small particle size (<80 microm), respectively.

Implementation of Quality Control Methods in Conjunction with Chemometrics Toward Authentication of Dairy Products

The implementation of novel and accurate quality and safety control methods in conjunction with chemometrics in various fields of science, particularly in food science, showed that this combination stands for a very powerful tool for detecting food authenticity. The latter reflects both geographic origin and variety. Dairy products, in particular, have repeatedly worried the public authorities in terms of authentication regarding origin and in view of the many illnesses occasionally due to products of specific origin. Therefore, the development of a robust and reliable system endowed with this discriminatory power (varietal and/or geographic) is of great importance, both in terms of public health and consumer protection.

NMR signal analysis to attribute the components to the solid/liquid phases present in mixes and ice creams

The NMR relaxation signals from complex products such as ice cream are hard to interpret because of the multiexponential behavior of the relaxation signal and the difficulty of attributing the NMR relaxation components to specific molecule fractions. An attribution of the NMR relaxation parameters is proposed, however, based on an approach that combines quantitative analysis of the spin-spin and spin-lattice relaxation times and the signal intensities with characterization of the ice cream components. We have been able to show that NMR can be used to describe the crystallized and liquid phases separately. The first component of the spin-spin and spin-lattice relaxation describes the behavior of the protons of the crystallized fat in the mix. The amount of fat crystals can then be estimated. In the case of ice cream, only the spin-lattice relaxation signal from the crystallized fraction is relevant. However, it enables the ice protons and the protons of the crystallized fat to be distinguished. The spin-lattice relaxation time can be used to describe the mobility of the protons in the different crystallized phases and also to quantify the amount of ice crystals and fat crystals in the ice cream. The NMR relaxation of the liquid phase of the mix has a biexponential behavior. A first component is attributable to the liquid fraction of the fat and to the sugars, while a second component is attributable to the aqueous phase. Overall, the study shows that despite the complexity of the NMR signal from ice cream, a number of relevant parameters can be extracted to study the influence of the formulation and of the process stages on the ice fraction, the crystallized fat fraction, and the liquid aqueous fraction.

Physical Properties of Ice Cream Containing Milk Protein Concentrates

Two milk protein concentrates (MPC, 56 and 85%) were studied as substitutes for 20 and 50% of the protein content in ice cream mix. The basic mix formula had 12% fat, 11% nonfat milk solids, 15% sweetener, and 0.3% stabilizer/emulsifier blend. Protein levels remained constant, and total solids were compensated for in MPC mixes by the addition of polydextrose. Physical properties investigated included apparent viscosity, fat globule size, melting rate, shape retention, and freezing behavior using differential scanning calorimetry. Milk protein concentrate formulations had higher mix viscosity, larger amount of fat destabilization, narrower ice melting curves, and greater shape retention compared with the control. Milk protein concentrates did not offer significant modifications of ice cream physical properties on a constant protein basis when substituted for up to 50% of the protein supplied by nonfat dry milk. Milk protein concentrates may offer ice cream manufacturers an alternative source of milk solids non-fat, especially in mixes reduced in lactose or fat, where higher milk solids nonfat are needed to compensate other losses of total solids.

Identification of two additives, locust bean gum (E-410) and guar gum (E-412), in food products by DNA-based methods

Locust bean gum (E-410) and guar gum (E-412) are high molecular weight galactomannans used by the food industry as versatile food additives. The compounds, although chemically closely related, do not have the same functional properties when used in foods, and the substitution or unadvertised addition of either could change the desired qualities of the product. Analytical discrimination between E-410 and E-412 is technically difficult since they only differ in their galactose: mannose ratios, being 1 : 4 and 1 : 2 for locust bean gum and guar gum, respectively. A qualitative DNA-based method is reported for the authentication of additives E-410 and E-412 in finished food products (ice cream, dehydrated desserts, milk derivatives, dehydrated soups, salad dressing, marmalade and meat) from small quantities of food. DNA sequences from the nuclear ribosomal spacers of Ceratonia siliqua and Cyamopsis tetragonoloba, the plant sources of E-410 and E-412, respectively, were used to design polymerase chain reaction primers specific for each additive (PA23/PA21 and PG22/PG21). Twenty-two foods were analysed for the presence of E-410 and E-412 additives by this single-step polymerase chain reaction-based method. Positive DNA amplifications with the E-410 and/or E-412 primers were obtained in all 19 samples reported to contain either additive.

Physical and sensory properties of dairy products from cows with various milk fatty acid compositions

Dairy products from milk of cows fed diets rich in polyunsaturated fatty acids have a more health-promoting fatty acid composition and are softer but often have oxidized flavors. Dairy products made from cow's milk that has more- or less-unsaturated fatty acid compositions were tested for differences in texture and flavor from those made from bulk-tank milk. The milk was manufactured into butter, vanilla ice cream, yogurt, Provolone cheese, and Cheddar cheese. The products were analyzed for fatty acid composition, physical properties, and flavor. Milk of cows with a more monounsaturated fatty acid composition yielded products with a more monounsaturated fatty acid composition that were softer and had a satisfactory flavor. Thus, selection of cows for milk fatty acid composition can be used to produce dairy products that are probably more healthful and have a softer texture.

Confirmation of the allergenic peanut protein, Ara h 1, in a model food matrix using liquid chromatography/tandem mass spectrometry (LC/MS/MS)

Enzymatic digestion of total protein along with liquid chromatography/tandem mass spectrometry (LC/MS/MS) was used to confirm the presence of a major peanut allergen in food. Several peptides obtained from the enzymatic digestion of the most abundant peanut allergen, Ara h 1, were identified as specific peptide biomarkers for peanut protein. Using ice cream as a model food matrix, a method was developed for the detection of the allergen peptide biomarkers. A key component of the method was the use of molecular mass cutoff filters to enrich the Ara h 1 in the protein extracts. By applying the method to ice cream samples containing various levels of peanut protein, levels as low as 10 mg/kg of Ara h 1 could routinely be detected. This method provides an unambiguous means of confirming the presence of the peanut allergen, Ara h 1, in foods and can easily be modified to detect other food allergens.

A novel method for the determination of synthetic colors in ice cream samples

A simple method has been developed for the extraction, separation, and determination of synthetic colors in ice cream samples. The process involves the breakdown of emulsion by neutral detergents (Triton X-100 and Tween 20) followed by extraction with petroleum ether for removal of fat. The aqueous colored solution obtained is treated with 5% acetic acid, and the uptake of color is carried out by a wool-dyeing technique. The color is eluted from the wool with 5% ammonia solution, the solution is evaporated to dryness, and the residue is dissolved in 60% ethanol for paper chromatography using trisodium citrate-ammonia-water (2 + 5 + 95, w/v/v) as the mobile phase. The colored spots from the paper chromatogram are cut and eluted with 60% ethanol, and the absorbance is measured at the respective lambda maximum corresponding to the Rf value of the appropriate standard. The recoveries of 6 colors, including sunset yellow FCF (SSYFCF), tartrazine, carmoisine, ponceau 4R, brilliant blue FCF (BBFCF), and fast green FCF from spiked samples with either detergent were found to be >90%. However, recoveries of erythrosine were 21 and 65% with Triton X-100 and Tween 20, respectively. Indigo carmine could not be recovered at all because of its fugitive property in 5% ammonia solution, which is used to strip the color from the wool. The sensitivity of the method with the use of Tween 20 is 1 ppm (1 microg/g) for the colors in spiked ice cream samples. With this method, we analyzed samples of 20 branded colored ice cream. The results showed the presence of tartrazine (8.4-43.3 ppm), SSYFCF (23.5-117.6 ppm), carmoisine (traces-53.2 ppm), erythrosine (3.5 ppm), and BBFCF (4.1 ppm) in the ice cream samples. Apart from 2 samples of tuttifruity, all of the ice cream samples showed the presence of permitted synthetic colors below the permissible level of 100 ppm established by the Prevention of Food Adulteration Act of India.

Short Communication: Impact of Formulation on Ice Cream Microstructures: an Oscillation Thermo-Rheometry Study

Oscillation thermo-rheometry was used to underline the existence of the different microstructures in ice cream. Varying ice cream formulations illustrated the impact of each ingredient, i.e., fat, proteins, and lipid emulsifiers, and their interactions on the establishment of different networks.

Ice Cream Structural Elements that Affect Melting Rate and Hardness

Statistical models were developed to reveal which structural elements of ice cream affect melting rate and hardness. Ice creams were frozen in a batch freezer with three types of sweetener, three levels of the emulsifier polysorbate 80, and two different draw temperatures to produce ice creams with a range of microstructures. Ice cream mixes were analyzed for viscosity, and finished ice creams were analyzed for air cell and ice crystal size, overrun, and fat destabilization. The ice phase volume of each ice cream were calculated based on the freezing point of the mix. Melting rate and hardness of each hardened ice cream was measured and correlated with the structural attributes by using analysis of variance and multiple linear regression. Fat destabilization, ice crystal size, and the consistency coefficient of the mix were found to affect the melting rate of ice cream, whereas hardness was influenced by ice phase volume, ice crystal size, overrun, fat destabilization, and the rheological properties of the mix.

Perception of melting and flavor release of ice cream containing different types and contents of fat

Temporal effects of dairy and vegetable fats (0 to 18%) on perception of strawberry flavor release and melting of ice cream were studied using the time intensity sensory method. Also, aroma and flavor attributes of the ice cream samples were evaluated. Only slight effects of fat on the rate of flavor release and flavor intensity were perceived. A slightly faster flavor release from the vegetable fat compared with dairy fat was noticed. Polydextrose and maltodextrin as bodying agents in the fat-free ice cream significantly increased flavor release and melting rate of the ice cream. Increasing fat content slightly retarded melting of ice cream in the mouth. No significant effect of the fat quality on perceived melting was noticed. Significant differences in aroma and flavor attributes of the fat-free and other samples were perceived. Intensity and sharpness of the strawberry aroma and flavor were greater in fat-free samples and they were perceived as nontypical. Fattiness and creaminess were highly correlated. Maltodextrin and polydextrose increased perceived fattiness and creaminess of fat-free ice cream.

Properties of frozen dairy desserts processed by microfluidization of their mixes

Sensory properties and rate of meltdown of nonfat (0% fat) and low-fat (2% fat) vanilla ice creams processed either by conventional valve homogenization or microfluidization of their mixes were compared with each other and to ice cream (10% fat) processed by conventional valve homogenization. Mixes for frozen dairy desserts containing 0, 2, and 10% fat were manufactured. Some of the nonfat and low-fat ice cream mixes were processed by microfluidization at 50, 100, 150, and 200 MPa, and the remaining nonfat and low-fat ice cream mixes and all of the ice cream mix were processed by conventional valve homogenization at 13.8 MPa, first stage, and 3.4 MPa, second stage. The finished frozen and hardened products were evaluated at d 1 and 45 for meltdown rate and for flavor and body and texture by preference testing. Nonfat and low-fat ice creams that usually had a slower meltdown were produced when processing their mixes by microfluidization instead of by conventional valve homogenization. Sensory scores for the ice cream were significantly higher than sensory scores for the nonfat and low-fat ice creams, but the sensory scores for the conventional valve homogenized controls for the nonfat ice cream and low-fat ice cream were not significantly different from the sensory scores for the nonfat ice cream and low-fat ice cream processed by microfluidization of the mixes, respectively. Microfluidization produced nonfat and low-fat ice creams that usually had a slower meltdown without affecting sensory properties.

Method development and analysis of retail foods and beverages for carotenoid food colouring materials E160a(ii) and E160e

An analytical method using high-performance liquid chromatography with photodiode array detection was developed and applied to the determination of the permitted food colour additives beta-carotene(E160a(ii)) and beta-apo-8'-carotenal (E160e) in foods and beverages. The scope of previously reported methods has been broadened to cover a wide range of retail foods and enzymatic hydrolysis has been used in place of saponification for high-fat samples. Quantitative results (greater then 0.1 mg kg(-1)) are given for the major colour principals trans-beta-apo-8'-carotenal and trans-beta-carotene. Semiquantitative results are given for the various cis-isomers of each colorant for which authentic reference standards were not available. The method has been used successfully for the analysis of a wide range of foodstuffs with differing fat content without the need for saponification, except for moderate- to high-fat foodstuffs containing significant levels of emulsifiers, for which it was limited. The results suggest that beta-apo-8'-carotenal (E160e) does not have widespread use in the UK. None of the samples exhibited a total beta-carotene content greater than 20 mg kg(-1) and none of the high-fat samples and only one of the 17 low-fat/beverage samples contained total beta-carotene at levels less than 0.1 mg kg(-1). The total beta-carotene contents of the low-fat/beverage samples ranged from 0.4 +/- 0.03 to 8.4 i 0.71 mg kg(-1), and the total beta-carotene contents of the high-fat samples ranged from 0.1 +/- 0.01 (jelly confectionery) to 18.5 +/- 0.98 mg kg(-1) (processed cheese).

Oxidation and textural characteristics of butter and ice cream with modified fatty acid profiles

The primary objective of this study was to evaluate oxidation and firmness of butter and ice cream made with modified milkfat containing enhanced amounts of linoleic acid or oleic acid. The influence of the fatty acid profile of the HO milkfat relating to product properties as compared with the influence the fatty acid profile of the HL milkfat was the main focus of the research. Altering the degree of unsaturation in milkfat may affect melting characteristics and oxidation rates, leading to quality issues in dairy products. Three milkfat compositions (high-oleic, high-linoleic, and control) were obtained by modifying the diets of Holstein cows. Ice cream and butter were processed from milkfat obtained from cows in each dietary group. Butter and ice cream samples were analyzed to determine fatty acid profile and firmness. High-oleic milkfat resulted in a softer butter. Solid fat index of high-oleic and high-linoleic milkfat was lower than the control. Control ice cream mix had higher viscosity compared with high-oleic and high-linoleic, but firmness of all ice creams was similar when measured between -17 and -13 degrees C. Nutritional and textural properties of butter and ice cream can be improved by modifying the diets of cows.

Anaphylaxis due to carrot as hidden food allergen

Carrot is frequently involved in food allergies and oral allergy syndromes, usually in association with other foods. Nevertheless, carrot alone is rarely responsible for severe systemic reactions. We report a case of anaphylactic shock due to the inadvertent ingestion of carrot as a hidden allergen contained in an ice-cream. The etiological role of carrot in provoking the symptoms was thoroughly ascertained through appropriate in vivo and in vitro assays and by excluding, through double-blind placebo-controlled challenge, the involvement of other ingredients of the food. We highlight once again the harm and risks due to hidden food allergens contained in commercial preparations and the importance of thorough patient education and information.

Effect of double homogenization and whey protein concentrate on the texture of ice cream

Ice cream samples were made with a mix composition of 11% milk fat, 11% milk solids-not-fat, 13% sucrose, 3% corn syrup solids (36 dextrose equivalent), 0.28% stabilizer blend, or 0.10% emulsifier and vanilla extract. Mixes were high temperature short time pasteurized at 80 degrees C for 25 s, homogenized at 141 kg/cm2 pressure on the first stage and 35 kg/cm2 pressure on the second, and cooled to 3 degrees C. The study included six treatments from four batches of mix. Mix from batch one contained 0.10% emulsifier. Half of this batch (treatment 1), was subsequently frozen and the other half (upon exiting the pasteurizer) was reheated to 60 degrees C, rehomogenized at 141 kg/cm2 pressure on the first stage and 35 kg/cm2 pressure on the second (treatment 2), and cooled to 3 degrees C. Mix from batch two contained 0.28% stabilizer blend. Half of this batch was used as the control (treatment 3), the other half upon exiting the pasteurizer was reheated to 60 degrees C, rehomogenized at 141 kg/cm2 pressure on the first stage and 35 kg/cm2 pressure on the second (treatment 4), and cooled to 3 degrees C. Batch three, containing 0.10% emulsifier and 1% whey protein concentrate substituted for 1% nonfat dry milk, upon exiting the pasteurizer was reheated to 60 degrees C, rehomogenized at 141 kg/cm2 pressure on the first stage and 35 kg/cm2 pressure on the second (treatment 5), and cooled to 3 degrees C. Batch four, containing 0.28% stabilizer blend and 1% whey protein concentrate substituted for 1% nonfat dry milk, upon exiting the pasteurizer was reheated to 60 degrees C, rehomogenized at 141 kg/ cm2 pressure on the first stage and 35 kg/cm2 pressure on the second (treatment 6), and cooled to 3 degrees C. Consistency was measured by flow time through a pipette. Flow time of treatment 3 was greater than all treatments, and the flow times of treatments 4 and 6 were greater than treatments 1, 2, and 5. Flow time was increased in ice cream mix by the addition of stabilizer. Double homogenization lowered ice cream mix flow time in the presence of stabilizer, but no difference in flow time was observed without stabilizer addition. Treatment 4 had a lower mean ice crystal size at 10 d postmanufacture compared with treatment 3; however, overall texture acceptability between treatments 3 and 4 was similar. Mean ice crystal size of treatment 6 was less at 18 wk postmanufacture compared with treatment 3; however, overall texture acceptability for treatments 3, 4, and 6 was similar. Mean ice crystal sizes of treatments 1, 2, and 5 were greater at 10 d and 18 wk compared with treatment 3. Sensory evaluation indicated that treatments 3, 4, and 6 had higher mean scores for icy, coldness intensity, and creaminess than treatments 1, 2, and 5 at 10 d and 18 wk postmanufacture.

Flow behavior characteristics of ice cream mix made with buffalo milk and various stabilizers

Ice cream made with buffalo milk, using optimum levels of various stabilizers of plant origin, was evaluated for its flow behavior characteristics, with the objective of producing an acceptable quality product. The minimum variation in the viscosity of mix was observed at three rates of shear (348.88, 523.33 and 1046.66 S(-1)) for all ice cream mixes. The flow behavior index (n) of all the mixes having optimum levels of various stabilizers was observed to be less than 1; indicating their pseudoplastic nature. Consistency coefficient (m) of sodium alginate was found to be 1.19; highest among all the stabilizers, followed by gelatin (1.17), karaya (1.08), guar gum (0.75), acacia gum (0.70), ghatti gum (0.36), and the control (0.29). The consistency coefficient (m) signifies the apparent viscosity of the pseudoplastic fluid. The viscosity of the mixes having various stabilizers (optimum levels) was found to be in descending order: Sodium alginate, gelatin, karaya, guar gum, acacia, ghatti and control.

Inulin determination for food labeling

Inulin and oligofructose exhibit valuable nutritional and functional attributes, so they are used as supplements as soluble fiber or as macronutrient substitutes. As classic analytical methods for dietary fiber measurement are not effective, several specific methods have been proposed. These methods measure total fructans and are based on one or more enzymatic sample treatments and determination of released sugars. To determine inulin for labeling purposes, we developed an easy and rapid anion-exchange high-performance liquid chromatography (HPLC) method following water extraction of inulin. HPLC conditions included an Aminex HPX- 87C column (Bio-Rad), deionized water at 85 degrees C as the mobile phase and a refractive index detector. The tested foods included tailor-made food products containing known amounts of inulin and commercial products (cookies, milk, ice creams, cheese, and cereal bars). The average recovery was 97%, and the coefficient of variation ranged from 1.1 to 5% in the food matrixes. The obtained results showed that this method provides an easier, faster and cheaper alternative than previous techniques for determining inulin with enough accuracy and precision for routine labeling purposes by direct determination of inulin by HPLC with refractive index detection.

Small volume bead assay for ovalbumin with electrochemical detection

A bead based sandwich enzyme immunoassay coupled to electrochemical detection for ovalbumin has been developed. The enzyme label alkaline phosphatase was used to convert the substrate 4-aminophenyl phosphate to electroactive product 4-aminophenol. The detection was done in a microdrop by continuously monitoring the enzyme turnover with a rotating disk electrode. This reduces dilution of the enzyme product, a key to achieving low detection limits. The assay developed has a detection limit of 0.1 ng ml-1. Assay sensitivity in complex matrices such as food and serum was compared.

Effects of milk fat, cocoa butter, or selected fat replacers on flavor volatiles of chocolate ice cream

Selected volatile compounds of chocolate ice creams containing 0.6, 4.0, 6.0, or 9.0% milk fat or containing 2.5% milk fat, cocoa butter, or one of three fat replacers (Simplesse, Dairy Lo, or Oatrim) were analyzed by gas chromatography and gas chromatography-mass spectrometry using headspace solid-phase microextraction. The headspace concentration of most of the selected volatile compounds increased with decreasing milk fat concentration. Fat replacers generally increased the concentration of volatiles found in the headspace compared with milk fat or cocoa butter. Few differences in flavor volatiles were found between the ice cream containing milk fat and the ice cream containing cocoa butter. Among the selected volatiles, the concentration of 2,5-dimethyl-3(2-methyl propyl) pyrazine was the most highly correlated (negatively) with the concentration of milk fat, and it best discriminated among ice creams containing milk fat, cocoa butter, or one of the fat replacers.

Effect of the fat globule sizes on the meltdown of ice cream

The meltdown of ice cream is influenced by its composition and additives and by fat globule size. The objective of this study was to examine the effect of fat globule size and fat agglomerate size on the meltdown stability of ice cream. Therefore, an ice cream mix (10% milk fat) was homogenized at pressures ranging from 0 to 30 MPa in single-stage, double-stage, and selective homogenization processes. The ice cream, produced on a continuous ice cream freezer, was characterized by an optimized meltdown test while, in addition, the fat globule sizes and the free fat content were determined in the mix and the molten ice cream. The meltdown was dependent on the fat agglomerate sizes in the unfrozen serum phase. Agglomerates smaller than a critical diameter led to significantly higher meltdown rates. Homogenization pressures of at least 10 MPa were sufficient to produce a stable ice cream. Furthermore, proof was provided that double-stage homogenization is not necessary for fat contents up to 10% and that selective homogenization is possible to produce stable ice creams. Based on these results a model was deduced describing the stabilizing mechanisms during the meltdown process.

Effect of milk fat, cocoa butter, and whey protein fat replacers on the sensory properties of lowfat and nonfat chocolate ice cream

Lowfat and nonfat chocolate ice creams were made with 2.5% of milk fat, cocoa butter, or one of two whey protein-based fat replacers, Dairy Lo or Simplesse. Polydextrose was added as required so that all formulations contained the same amount of total solids. Ice cream was stored at a control temperature of-30 degrees C. Hardness, viscosity, and melting rate were measured by physical methods. Trained panelists conducted descriptive sensory analyses of the samples at 0, 6, and 12 wk. Attribute ratings were analyzed by analysis o variance with least significant difference mean separation and orthogonal contrasting. Data were also analyzed by multivariate analysis of variance with canonical variate analysis. Consumer acceptance (n = 50) did not differ among the fresh ice creams (wk 0). Ice cream containing milk fat had less intense cocoa flavor and was more resistant to textural changes over time compared with the other ice creams. Simplesse was more similar to milk fat than was Dairy Lo in its effect on brown color, cocoa flavor, cocoa character, and textural stability but was less similar in terms of thickness and mouthcoating.

Rheological properties of ice cream mixes and frozen ice creams containing fat and fat replacers

Ice cream mixes and frozen ice creams at milk fat levels of 12%, 8%, 6%, 6% plus a protein-based fat replacer, and 6% plus a carbohydrate-based fat replacer were evaluated for viscoelastic properties by dynamic testing with sinusoidal oscillatory tests at various frequencies. The storage modulus (G'), loss modulus (G"), and tan delta (G"/G') were calculated for all the treatments to determine changes in the viscous and elastic properties of the mixes and frozen ice creams due to fat content. In ice cream mixes, G' and G" exhibited a strong frequency dependence. The G" was higher than G' throughout the frequency range (1 to 8 Hz) examined, without any crossover, except for the 12% mix. Elastic properties of the ice cream mixes decreased as fat content decreased. Tan delta values indicated that fat replacers did not enhance the elastic properties of the ice cream mixes. In all frozen ice creams, G' and G" again showed a frequency dependence throughout the range tested (0.5 to 10 Hz). The amount of fat in ice creams and the degree of fat destabilization affected the elasticity in the frozen product. Even though the ice creams did not have significant elastic properties, when compared as a group the samples with higher fat content had higher elastic properties. The addition of protein-based and carbohydrate-based fat replacers did not enhance the elastic properties of the ice creams but did increase the viscous properties.