Effect of thermal and defatting treatments on the composition, protein profile and structure of house cricket (Acheta domesticus) protein extracts

This study investigated the impact of blanching (100 °C, 40 s), defatting method (maceration, Soxhlet) and solvent polarity (hexane, ethanol) on the profile, structure and solubility of house cricket protein extracts. Blanching and Soxhlet using ethanol impacted the protein profile, with a lower content of myosin heavy chain and a higher abundance of low molecular weight proteins (<25 kDa). Moreover, ethanol induced aggregation of non-blanched cricket proteins, with a 13-72% reduction in protein recovery yield. The protein secondary structure of non-blanched extracts was also affected by ethanol with 18% more β-sheets. Furthermore, blanching resulted in a lower protein surface hydrophobicity by a factor of 3 to 7, with no impact of solvent polarity. Finally, the solubility of protein extracts remained >75%, regardless of the blanching and defatting methods. These findings, combined with the evaluation of techno-functional properties, could be used for the development of cricket-based protein ingredients for food formulations.

Use of instant controlled pressure drop technology for the preservation of edible insects' (yellow mealworm) quality: assessment of microbial inactivation

The world population is expanding, and with it, so is the need for proteins for the food and feed sectors. Conventional livestock production is correlated with negative environmental repercussions such as global warming, land degradation, and biodiversity loss. The nutritional content of edible insects is comparable to that of conventional meat, and insect farming offers various environmental advantages over livestock production, making it a favorable sustainable protein resource. However, to be placed on the market, insects should be processed, and their microbial load should be within the accepted range of the European Commission regulation (EU) 2021/882. The purpose of this research is to investigate the use of instant controlled pressure drop (DIC) technology for the microbial inactivation of yellow mealworm larvae. This innovative decontamination treatment was compared to blanching in hot water, the conventional processing method. We also investigated the impacts on enzymatic browning. Results showed that the application of rapid (20 s) DIC treatment at 0.3 MPa allowed reducing the total aerobic count and the total yeast and mold count of larvae below the thresholds authorized by the commission regulation. Pressure, temperature, and number of cycle factors were found to have significant effects on the decontamination, while the treatment time had no effect for most treatments. In regard to blanching, we were able to get the authorized load at 90 °C for 360 s. Decimal reduction times for DIC and blanching treatments were found to be 3.8 s and 67.8 s for total aerobic count, and 3 s and 57 s for total yeast and mold count, respectively. Furthermore, DIC-treated larvae showed a significant increase in juice color brightness, which could be traced back to the oxidative enzymatic inactivation of larvae, whereas there was a slight difference between blanched and untreated larvae juice colors.

Occupational injuries among female seafood processing workers in Prakasam district, Andhra Pradesh, India

Women play a significant role in the processing of the seafood after the harvesting process and are mostly engaged in grading, peeling, cutting, and packing activities. Injuries during their job make them vulnerable to many problems and lead to many severe consequences. The present study aimed to identify the frequency and factors associated with occupational injuries among the workers in Prakasam district, Andhra Pradesh. This cross-sectional study included 257 women seafood processing workers. Simple random sampling technique was used to select the participants. The data were collected through face to face interviews using a predesigned questionnaire. Data were analyzed using SPSS. The prevalence of injuries among 257 women seafood processing workers was 74.3 percent. Age of the worker, job satisfaction, working hours per day, breaks duration between work, and blanching of hands (paleness of hands due to vasoconstriction) were found to be statistically significantly associated factors with injury occurrence among women seafood processing workers. Thus, to conclude, the frequency of occupational injuries among the women seafood processing workers is high and is associated with several occupational factors.

Impacts of novel blanching treatments combined with commercial drying methods on the physicochemical properties of Irish brown seaweed Alaria esculenta

Alaria esculenta is one of the most abundant edible brown seaweeds in Irelandandisconsidered an excellent source of nutrients, sought after by the food, nutraceutical and pharmaceutical industries. Seaweed is typically blanched and dried prior to consumption to enhance the end-product quality attributes and shelf life. Three blanching techniques were examined in this work; conventional hot water blanching, novel ultrasound blanching and microwave blanching. The L* and b*colour metrics were affected significantly (P < 0.01) by the processing methods. There were 76 volatile compounds detected in blanched and dehydrated Alaria esculenta. Freeze-dried samples after treatment with microwave alone (at 1000 W) and microwave (800 W) combined with ultrasound (at 50% amplitude) had the highest retention rate of volatile compounds (up to 98.61%). Regarding mineral content, drying methods significantly affected (P < 0.05) the content of Ca, Co, Cu and Fe, while blanching treatments significantly affected (P < 0.05) the content of Na, Cu, Fe and Mn.

Ethanol and blanching pretreatments change the moisture transfer and physicochemical properties of apple slices via microstructure and cell-wall polysaccharides nanostructure modification

The impacts of ethanol pretreatment and blanching on moisture transfer, microstructure, and nanostructure of cell-wall polysaccharides of apple slices were studied. The physicochemical properties, namely, color, rehydration, and antioxidant capacity were also evaluated. The results corroborated that the use of ethanol and blanching reduced drying time 45-60% and 21-42% at various drying temperatures (50, 60, 70, and 80 °C), respectively, compared to controls. Ethanol loosened the cell wall structure, thereby reducing the internal resistance of moisture diffusion, and the changes in cell wall structure caused by blanching were mainly due to the β-elimination degradation of pectins. Both samples of ethanol pretreatment and blanching possessed lower browning index and higher antioxidant capacity compared with the untreated ones. Overall, ethanol pretreated products exhibited the shortest drying time, less color change and higher antioxidant capacity. These results provide new insights on possible mechanisms about ethanol pretreatment and blanching to improve drying.

Effect of pre-treatment and drying methods on the content of minerals, B-group vitamins and tocopherols in kale (Brassica oleracea L. var. acephala) leaves

Dried vegetables are widely used in food production. Kale leaves, due to their high health-promoting properties, can be a valuable raw material for drying. The aim of the study was to evaluate the effect of blanching, drying methods (air-drying, freeze-drying), the time and temperature of storage on the content of ash, minerals, vitamins B₁, B₂, and tocopherols in dried kale products. The dried products were evaluated directly after processing and after 12 months of storage at ambient temperature, 18–20 °C and cold temperature, 8–10 °C. In 100 g dry matter from fresh raw material the dominant minerals were potassium (2613 mg), calcium (1346 mg), phosphorus (432 mg), magnesium (129 mg). Kale leaves had 0.828 mg vitamin B₁, 1.533 mg vitamin B₂ and 16.55 mg total tocopherols per 100 g of dry matter. Blanching, applied prior to drying, significantly reduced the levels of minerals (3–38%) and vitamins (8–45%), except for calcium, zinc and manganese. This pre-treatment had, however, a beneficial effect, especially on vitamin retention during the storage of dried products. After 12 month storage, the losses of vitamin B₁, B₂ and total tocopherols in dried, previously blanched, raw materials ranged from 3 to 10%, 1 to 4%, and 1 to 16%, respectively, depending on the type of sample. In the dried products obtained from unblanched raw material, the losses were larger and amounted to 10–17%, 8–16% and 4–17%, respectively. Throughout drying and storage, the minerals examined were fairly stable. Dried kale is generally a good source of minerals and vitamins. However, blanching before drying is recommended. In addition, freeze-drying and storage in cold temperature allows for higher vitamin preservation in dried kale.

Improving Recombinant Protein Recovery from Plant Tissue Using Heat Precipitation

Plants are increasingly viewed as suitable expression hosts for the production of recombinant proteins, especially when oxidative folding and/or posttranslational modification is essential for protein stability and functionality. In contrast to traditional platforms such as yeast and mammalian cells, where the product is secreted into the culture medium, recombinant proteins expressed in plants are usually retained within the cells so additional effort is required during extraction and purification. Various extraction processes are used to release soluble proteins from plant tissues, followed by clarification to remove fibers and particulates before the target protein is purified. Fermentation media generally contain few proteins, making it easier to recover a secreted product, whereas the green juice extracted from plants usually contains a large number of host proteins that interfere with target isolation and purification. In this chapter, we describe the use of heat precipitation to remove a large portion of the host cell proteins, thus improving the efficiency of subsequent purification steps and the quality of the purified recombinant protein.

Effect of fruit thermal processing on ethyl carbamate content in maesil (Prunus mume) liqueur

The thermal effect of maesil on the content of ethyl carbamate and its precursors during one-year ripening of maesil liqueur was investigated. Fresh maesil (control), fruit blanched for 2 min (blanched), and fruit blanched and dried for 15 h at 50 °C (blanched/dried) were soaked in the liquor containing 25% alcohol at a ratio of 1:2 (w/w) for 100 days at 25 °C and the liquid was further ripened for 260 days. Ethyl carbamate ranged from 13.1 to 204.4 μg/kg with the highest value at 210 day. Thermally treated samples had higher ethyl carbamate concentration than the control, suggesting that thermal treatment increased the formation of ethyl carbamate. A positive correlation between ethyl carbamate content and β-glucosidase activity in all samples indicated that enzymatic hydrolysis of amygdalin by β-glucosidase determined ethyl carbamate concentration during the fermentation of maesil liqueur.

Effects of two pre-treatments, blanching and soaking, as processing modulation on non-enzymatic browning developments in three yam cultivars from Ghana

Non-enzymatic browning develops in dry-cooked foods and those with high carbohydrate develop acrylamide, a neurotoxin and potential carcinogen. However, some non-enzymatic browning products have reducing properties. We hypothesized that non-enzymatic browning and reducing power, a measure of antioxidant activity, of processed yam are affected by pre-treatment. Peeled yam cultivars (KM, RKD and SO89) in chunks were pre-soaked (0, 3, 6, 12, 18, and 24 h) in distilled water or pre-blanched (0, 1, 2, 3, 4, and 5 min) in steam. Pre-treated samples were deep-fried at 180 °C for 15 min or roasted at 220 °C for 30 min. Soluble solids, titratable acidity and pH of yam tissues and soaking water were determined. pH of the soaked yam tissues showed a positive relation with non-enzymatic browning. Pre-soaked fried KM and roasted RKD showed a significant decrease in non-enzymatic browning intensities. The reducing power of the cooked yams ranged between 78.94 and 185.92 % of ascorbic acid, and was affected by the different pre-treatment and dry-cooking methods.

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Soaking effectively in decreased non-enzymatic browning in both fried and roasted products of yam varieties.

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Blanching affected non-enzymatic browning in the processed yam tissues differently for the different varieties.

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pH, titratable acidity and soluble solids are important in non-enzymatic browning of soaked yam tissues.

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Pre-treated yams have high reducing power as antioxidant activity.

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Reducing power of processed yam is dependent on the variety and the processing method.

Blanching effects of radio frequency heating on enzyme inactivation, physiochemical properties of green peas (Pisum sativum L.) and the underlying mechanism in relation to cellular microstructure

Fresh green peas require blanching to terminate enzymatic reaction induced quality deterioration before frozen storage. Radio frequency (RF) heating is a novel way of dry blanching for fruits and vegetables with high processing efficiency. In this study, blanching effects of RF heating on relative activities of lipoxygenase (LOX) and peroxidase (POD), physiochemical properties as well as cellular morphology changes of green peas were investigated. Results showed relative activities of pea LOX and POD reduced to 0.90 ± 0.78% and 1.10 ± 0.71%, respectively at 85 °C by RF heating with an electrode gap 105 mm. Weight loss, color, texture and electrolyte leakage of peas changed significantly with increasing temperature (60-85 °C). Ascorbic acid, chlorophyll and mineral contents had different loss after RF processing and long term heating at 115 mm exacerbated the loss of nutrients. Microstructure features showed the deconstruction of pea cell well and starch granule gelatinization.

Efficient control of acrylamide in French fries by an extraordinarily active and thermo-stable l-asparaginase: A lab-scale study

As a potential carcinogen, acrylamide (AA) widely exists in starch-rich foods during frying, triggering international health alerts. l-Asparaginase (l-ASNase, EC 3.5.1.1) could efficiently inhibit the AA by hydrolyzing its precursor l-Asparagine. Here, a novel recombinant l-ASNase from Palaeococcus ferrophilus was identified for the first time. The purified enzyme exhibited its highest activity at pH 8.5 and 95 °C and retained more than 70% relative activity after incubation at 80 °C for 2 h. Compared to untreated French fries, the AA content in the enzyme-treated (10 U/mL, 85 °C, 15 min) French fries was significantly reduced by 79%. Notably, the l-ASNase could remain over 98% of initial activity after three months of storage at 4 °C, suggesting good storage stability. These results demonstrated that P. ferrophilusl-ASNase could be a great candidate in controlling AA in the food industry, especially at high blanching temperature.

Comparative nutritional and microbiological quality of ready to cook mixed vegetable curry

Increasing urbanization, busy lifestyles has been providing a huge impetus to prefer ready to cook (RTC) food products. The research project was conducted to develop such a RTC product which fits the busy lifestyle of people as well as does not compromise on part of nutritional profile. The curry was prepared by washing, cutting, boiling (till vegetables gets soft) and blanching (5 min in 5% brine solution) followed by drying of five seasonal vegetables viz., carrot, peas, potato, cauliflower, beans in hot air dryer at 65 ± 5 °C for 10-12 h. A standardized gravy mix powder (onion, garlic, spices and herbs) was used to add flavor. Serving size for one person i.e. sachet contained 25 g dried vegetables, 10 g gravy mix powder and 200 ml water was prepared and packed. The recipe was finalized after sensory trials. The curry was ready in approximately 5 min in pressure cooker. The product remained well acceptable up to 4 months when packed in LDPE pouches under normal room temperature conditions. However, the shelf life of 4 months at 25 °C for a dried product is by all means considered good by the general expectations of dried foods and keeping the quality of dried foods reported in the literature.

Effect of post inoculation drying procedures on the reduction of Salmonella on almonds by thermal treatments

Since two outbreaks of salmonellosis were linked to the consumption of almonds in 2001 and 2004, the study of pathogen inactivation kinetics in almonds has been encouraged, often by conducting inoculated challenge studies. The inoculation method could affect the results of such challenge studies, because of the possible increase of moisture on the almonds resulting from a wet inoculation procedure, which may result in a potential overestimation of the effectiveness of treatments used to pasteurize almonds in industrial settings. Salmonella enterica serotype Enteritidis phage type 30 (PT30) isolated from an almond-linked outbreak was inoculated on nonpareil almonds and dried by accelerated (drying the inoculated almonds at 37 °C for 12 h) and conventional (drying inoculated almonds overnight at room temperature) drying methods, before treating the almonds with hot water (blanching) at 88 °C or hot oil (oil roasting) at 127 °C. The Weibull model explained the death of this pathogen on almonds better than log-linear model for oil roasting, whereas both log-linear and Weibull models were similarly effective for blanching. For blanching, the D values for Salmonella Enteritidis PT30 were 12.7 and 10.7 s with accelerated and conventional drying, respectively. For oil roasting, the b-values were 4.59 and 4.18 s with accelerated and conventional drying, respectively. Based on the models, it was concluded that the accelerated drying process resulted in a significantly smaller reduction in Salmonella Enteritidis PT30 on almonds in comparison to conventional drying for both blanching and roasting. Although conventional drying led to significantly lower D or b - values (depending on the model), this difference is not likely to affect the current processing parameters used by the almond industry.

Water state and sugars in cranberry fruits subjected to combined treatments: Cutting, blanching and sonication

To ease the mass exchange in fruit tissues, cutting and blanching are traditionally performed. However, recently, unconventional methods such as sonication are becoming more popular, which cause several alterations of physical and chemical properties as well as microstructure changes. The aim of this work was to evaluate the distribution of water inside the cranberry fruits, microstructural changes and sugars content, following traditional and sonication pre-treatments in osmotic solutions. TD-NMR spectroscopy was used to measure the transverse relaxation time (T₂) and intensity of proton pools in different cellular compartments. The microstructure of the samples was evaluated by SEM microscopy, sugars content by HPLC and sucrose melting temperature and enthalpy by DSC. Different pre-treatments appeared to promote microstructure alterations and loss of water from vacuole and cytoplasm/extracellular space, more pronounced in cut and blanched samples. Cutting and blanching followed by osmotic dehydration with assisted sonication eased sucrose penetration into the tissue.

Combined pre-treatments effects on zucchini (Cucurbita pepo L.) squash microbial load reduction

Freezing vegetables requires pre-treatments to reduce microbial load and destroy enzymes that impair the frozen product quality. So far blanching has been the most effective pre-treatment, preferred by the food industry, despite its severity: heating up to temperatures close to 100 °C for 1-3 min causes sensory and texture changes in most horticultural products. Alternative blanching treatments, using UV-C radiation combined with milder thermal treatments or with thermosonication, may improve the quality of the final frozen vegetables. Zucchini (Cucurbita pepo L.), the vegetable under study, has an availability in fresh restricted to a season, needing therefore to be often frozen to be used throughout the year. In this study, its surface was first inoculated with two vegetable contaminants, Enterococcus faecalis and Deinococcus radiodurans cells, which are resistant, respectively, to high temperatures and to radiation and then submitted to several blanching treatments, single or combined, and the effect on these microorganisms reduction was evaluated. As single treatments, water blanching (the control treatment, as it is the blanching treatment traditionally used) was applied up to 180 s at temperatures ranging from 65 to 90 °C, and UV-irradiation applied in continuous. As combined pre-treatments, water blanching combined with UV-C (continuous or in pulses), and thermosonication (20 kHz at 50% of power) combined with UV-C pulses were also studied. The continuous UV-C radiation incident irradiance was 11 W/m² up to 180 s, and the pulses at incident radiance of 67 W/m², lasting 3.5 s each (35 pulses). Mathematical modeling of bacterial reduction data was carried out using the Bigelow, the Weibull and Weibull modified models, and estimation of their respective kinetic parameters proved that the latter models presented a better fit below 75 °C. The best results proved to be the combination of water blanching at temperatures as low as 85 °C during <2 min with 25 pulses of UV-C (incident irradiance of 67 W/m²) or thermosonication at 90 °C also combined with UV-C pulses, both resulting in 3 log reductions of both microorganisms under study. These results proved to overcome what industry is requiring so far (a 2 log microbial reduction in 3 min), hence minimizing quality changes of frozen zucchini.

Effects of processing techniques on drying characteristics, physicochemical properties and functional compounds of green and red chilli (Capsicum annum L.) powder

This study was aimed to investigate the effect of processing techniques on the characteristics of green and red chilli powder. Four samples, such as pretreated green chilli paste (PTGP), pretreated green chilli longitudinal slit (PTGL), pretreated whole red chilli (PTWR) and untreated green chilli paste (UTGP), were prepared and dried at 60 °C in a cabinet dryer. The pretreatment was blanching in acetic acid solution and soaking immediately in a combined solution of Na₂S₂O₅ and CaCl₂. Pretreated samples took a shorter drying time than the untreated sample in reducing moisture content from 86.31 to 8%. Pretreatment before drying resulted in retaining total chlorophyll (~ 86%), phenolic compounds (~ 32%), green color, and pungency of chilli. Analysis result indicated that more than 60% retention of β-carotene was found while retention of ascorbic acid was comparable. Conclusively, this research reveals a good nutritional profile in cabinet dried green chilli powder, which may open the scope for commercial production.

Heating tomato puree in the presence of lipids and onion: The impact of onion on lycopene isomerization

Z-lycopene isomers are more bioavailable than all-E-lycopene, especially 5-Z-lycopene. Based on our observations, the addition of unblanched onion could favor Z-isomerization of lycopene (by more than 94%) during heating tomato-onion-extra virgin olive oil (EVOO) purees at 90 °C for 2 h. The increase in Z-lycopene was correlated linearly with the addition of unblanched onion, with R² > 0.92, and increased rates of 5-Z-lycopene were 3-4 times higher than for 9-Z-lycopene and 13-Z-lycopene. Diallyl disulfide (DADS), formed by alliinase-catalyzed breakdown of non-volatile precursors in onion, contributed to these increases and correlated linearly (R² > 0.79, 0-0.50 mg/g puree) with increased Z-lycopene. Increased rates of 5-Z-lycopene were also 3-4 times higher than for 9-Z-lycopene and 13-Z-lycopene. However, blanching of onion, in tomato-onion-EVOO purees, before heating, significantly decreased the effect of onion on Z-isomerization of lycopene.

Applications of water blanching, surface contacting ultrasound-assisted air drying, and their combination for dehydration of white cabbage: Drying mechanism, bioactive profile, color and rehydration property

This work studied the influences of water blanching pretreatment (30 s), surface contacting ultrasound (492.3 and 1131.1 W/m²) assisted air drying, and their combination on drying kinetics and quality of white cabbage. Contacting sonication was performed by placing samples on an ultrasonic vibration plate, and the drying temperature was 60 °C. Through drying kinetic analysis and numerical simulation considering internal and external resistances and shrinkage, it was found that both blanching pretreatment and contacting sonication during drying intensified internal water diffusion and external water exchange to shorten cabbage drying time. Meanwhile, blanching pretreatment was more effective to enhance the drying process. The largest reduction of drying time (from 145 min to 24 min) was obtained when sequential blanching and contacting sonication at 1131.1 W/m² were conducted. Dehydrated cabbages with blanching pretreatment were characterized by green color and high retention of vitamin C, while a severe loss of vitamin C was found in dried cabbages without blanching pretreatment. Moreover, although both blanching and contacting sonication shortened the drying time, the losses of phenolics, glucosinolates and resulting breakdown products were not alleviated. Contents of total phenolics, one glucosinolates (sinigrin) and one glucobrassicin breakdown product (indole-3-acetoritrile) in only air dried cabbages were significantly (p < 0.05) higher than that in samples dried by sequential blanching and contacting ultrasound-assisted drying. The changes of glucosinolate profile and resulting degradation products under different treatments were irregular, due to complex bioconversion pathways included.

Facial Blanching after Local Anesthesia Injection: Clinico-anatomical Correlation-Review of Literature

Facial blanching as a complication of local anesthesia is reported in dentistry. Inadvertent arterial penetration and subsequent vasospasm has been accepted as the mechanism of this phenomenon. Most cases occur after inferior alveolar nerve block injection. In this article, five cases are reported after Gow-Gates injection, maxillary nerve block via greater palatine foramen, inferior alveolar nerve block, and maxillary buccal infiltration. It is the largest case series in this topic. Also, clinico-anatomical correlation between facial–mucosal blanching and the site of intra-arterial injection is explained. To the best of our knowledge, partial blanching of the face subsequent to buccal infiltration is reported for the first time in this article. Cutaneous surgeon should be aware of this complication and should not carry out unnecessary treatment.

Downstream processing of a plant-derived malaria transmission-blocking vaccine candidate

Plants as a platform for recombinant protein expression are now economically comparable to well-established systems, such as microbes and mammalian cells, thanks to advantages such as scalability and product safety. However, downstream processing accounts for the majority of the final product costs because plant extracts contain large quantities of host cell proteins (HCPs) that must be removed using elaborate purification strategies. Heat precipitation in planta (blanching) can remove ∼80% of HCPs and thus simplify further purification steps, but this is only possible if the target protein is thermostable. Here we describe a combination of blanching and chromatography to purify the thermostable transmission-blocking malaria vaccine candidate FQS, which was transiently expressed in Nicotiana benthamiana leaves. If the blanching temperature exceeded a critical threshold of ∼75 °C, FQS was no longer recognized by the malaria transmission-blocking monoclonal antibody 4B7. A design-of-experiments approach revealed that reducing the blanching temperature from 80 °C to 70 °C restored antibody binding while still precipitating most HCPs. We also found that blanching inhibited the degradation of FQS in plant extracts, probably due to the thermal inactivation of proteases. We screened hydrophobic interaction chromatography materials using miniature columns and a liquid-handling station. Octyl Sepharose achieved the highest FQS purity during the primary capture step and led to a final purity of ∼72% with 60% recovery via step elution. We found that 30-75% FQS was lost during ultrafiltration/diafiltration, giving a final yield of 9 mg kg-1 plant material after purification based on an initial yield of ∼49 mg kg-1 biomass after blanching.

Process kinetics on physico-chemical and peroxidase activity for different blanching methods of sweet corn

Blanching was performed to inactivate the enzyme using microwave, steam and hot water blanching methods and effect on the enzymatic activity, chemical properties and physical properties of the sweet corn were studied. The effectiveness of each blanching process was evaluated by measuring the loss of peroxidase activity, which was lost after 60, 90 and 120 s with k-values 0.016, 0.024 and 0.028 s^-1 following first order kinetics for microwave, steam and hot water blanching respectively. The total sugar, ascorbic acid, moisture content, kernel mass and geometric diameter changed from 8.40 to 6.30, 7.20 and 7.50 g/100 g; 7.15 to 5.70, 6.10 and 6.60 mg/100 g; 76 to 79.20, 78.20 and 75.30%; 0.47 to 0.53, 0.50 and 0.42 g; 8.00 to 8.50, 8.30 and 7.20 mm at optimum level of blanching during microwave, steam and hot water blanching respectively, indicating higher retention of total sugar and ascorbic acid in microwave blanching. The change in colour, especially increase in brownness was observed during blanching processes. The average R² for zero-order model was 0.945, suggesting use of model for prediction of physico-chemical parameters during blanching process of sweet corn.

Physico-chemical properties, bioactive compounds and color parameters of coriander puree: effect of pretreatments and freezing

Coriander, one of the most widely utilized herb, is a short duration herb having very short shelf life. The present investigation involved development of an innovative process for enhancing the utilization and the availability of this herb. This process involves pretreatment, blanching and freezing to form ready to use frozen coriander puree tablets. Coriander was subjected to different pretreatments viz. T1: 0.25% potassium metabisulphite, T2: 0.5% citric acid and T3: 0.2% potassium metabisulphite + 0.1% magnesium chloride + 0.1% sodium bicarbonate. The pretreated coriander was blanched in hot water for 2 min and processed into puree having total soluble solids (TSS) as 2.5, 3.5 and 4.5°Brix. Pretreatments significantly affected the all quality parameters except moisture content. TSS had non significant effect on a* value, chroma, pH ascorbic acid and total flavonoid content of processed coriander puree. Coriander puree obtained with T1 pretreatment exhibited better quality than with other pretreatments. T1 pretreated and blanched puree was then frozen in silicon moulds using air blast freezing and deep freezing. Frozen puree tablets were evaluated for quality. The best quality coriander puree obtained from T1 pretreated, blanched puree having TSS 4.5°Brix frozen by continuous air-blast freezing (at a conveyor speed of 4.40 × 10^-3m/s) comparable results to deep freezing having. All quality parameters, except pH, were significantly affected by TSS level of puree as well as different freezing treatments.

Effect of pulsed electric field on texture and drying time of apple slices

Effect of pulsed electric field (PEF) strength, pulse duration and temperature used during PEF assisted blanching pretreatment on energy input, cell disintegration index and drying time of apple slices was studied. A central composite rotatable design was used for designing the experiment and to visualize the effect of variables on responses. The level of variables used in the design varied from 1 to 2 kV cm^-1, 25 to 75, and 60 to 80 °C for electric field strength, number of pulses and temperature of water during PEF assisted blanching pretreatment, respectively. The variables affected significantly the responses and polynomial quadratic models employed to visualize the effect of variables on different responses were found to fit well with high R² values (0.84-0.99) indicating fitness of the models in describing the effect of variables on responses. An optimized condition for variables was derived at 1.25 kV cm^-1, 50, and 80 °C for electric field strength, number of pulses temperature during PEF assisted blanching pretreatment, respectively with a desirability value of 0.85. High correlations were recorded between predicted and actual values for responses at optimized conditions of variables and the same can be used for production of dehydrated apple slices with low energy input.

Blanching and antimicrobial mixture (potassium sorbate-sodium benzoate) impact on the stability of a tamarillo (Cyphomandra betacea) sweet product preserved by hurdle technology

In a previous study, a stable tamarillo sweet product (TSP) was obtained by applying hurdle technology (low pH, reduction of water activity, sodium benzoate addition and stored at 4 °C, with oxygen and light protection). In order to improve the TSP shelf life, it was decided to employ a mixture of antimicrobial agents (sodium benzoate and potassium sorbate 50-50%) and fruit blanching. The phenolic compounds content, total monomeric anthocyanins of TSP, antioxidant capacity, microbial growth (aerobic mesophilic bacteria, molds and yeasts) and net color change were evaluated, during 63 days. The results showed that the use of blanched tamarillo and the addition of the antimicrobial mixture increased the TSP stability, in which the microbial counts were maintained below the limits established by the official food safety norms, without effects the antioxidant compounds and color.

Effects of radio frequency assisted blanching on polyphenol oxidase, weight loss, texture, color and microstructure of potato

This paper is focused on the effects of radio frequency (RF) heating on the relative activity of polyphenol oxidase (PPO), weight loss, texture, color, and microstructure of potatoes. The results showed that pure mushroom PPO was almost completely inactivated at 80 °C by RF heating. The relative activity of potato PPO reduced to less than 10% with increasing temperature (25-85 °C). Enzyme extract showed the lowest PPO relative activity at 85 °C after RF treatment, followed by the potato cuboids and mashed potato, about 0.19 ± 0.017%, 3.24 ± 0.19%, and 3.54 ± 0.04%, respectively. Circular dichroism analysis indicated that RF heating changed the secondary structure of PPO, as α-helix content decreased. Both electrode gap and temperature had significant effect (P < .05) on weight loss, color, and texture of the potato cuboids. Microstructure analysis showed the changes of potato cell and starch during RF heating.

Thermal Inactivation of Listeria monocytogenes and Salmonella during Water and Steam Blanching of Vegetables

Thermal inactivation of Listeria monocytogenes and Salmonella was evaluated on peas, spinach, broccoli, potatoes, and carrots that were treated with hot water and steam. One gram-positive bacterium, L. monocytogenes, and one gram-negative bacterium, Salmonella, were selected as pertinent human pathogens for evaluation. Samples were inoculated with a composite of five strains each of L. monocytogenes and Salmonella to achieve approximately 10⁸ to 10⁹ CFU/g. Inoculated samples were treated with hot water at 85 and 87.8°C and with steam at 85 and 96.7°C for up to 3.5 min. A greater than 5-log reduction of L. monocytogenes and Salmonella was achieved on all products within 0.5 min by hot water blanching at 85 and 87.8°C. Steam blanching at 85°C reduced Salmonella populations by greater than 5 log on spinach and peas within 2 min and on carrots and broccoli within 3.5 min. Populations of Salmonella were reduced by more than 5 log within 1 min on carrot, spinach, and broccoli and within 2 min on peas by steam blanching at 96.7°C. Steam blanching at 85°C reduced L. monocytogenes populations by more than 5 log on carrots and spinach within 2 min and on broccoli and peas within 3.5 min. L. monocytogenes populations were reduced more than 5 log within 1 min on carrot, spinach, peas and broccoli by steam blanching at 96.7°C. Longer treatment times and higher temperatures were required for steam-blanched samples than for samples blanched with hot water. Results suggest that hot water and steam blanching practices commonly used by the frozen vegetable industry will achieve the desired 5-log lethality of L. monocytogenes and Salmonella and will enhance microbiological safety prior to freezing.

Combined effect of blanching and sonication on quality parameters of bottle gourd (Lagenaria siceraria) juice

This study evaluated the combined effect of blanching and sonication treatment on selected quality parameters of bottle gourd juice (BGJ). Bottle gourd cubes were blanched and juice was extracted. Effect of frequency (20-50kHz), amplitude (50-90%) and time (10-30min) was also studied on quality parameters like titratable acidity (TA), pH, total soluble solids (TSS), physical stability (PS), ascorbic acid (AA), total phenolics (TP), total carotenoids (TC), browning index (BI), total plate count (TPC) and yeast & mold count (Y&M) of BGJ to derive the level of these parameters. Combined effect of blanching followed by sonication (BFS) showed significant (P⩽0.05) change in all quality parameters except TA. Highest percentage of TSS (5.9°B), PS (2%), AA (18.99mg/100g), TP (1010mg/100g) and TC (5.8mg/100g) was observed at 70% amplitude, 50kHz frequency and 20min. Results suggested 70% amplitude, 50kHz frequency and 20min as best treatment conditions for processing of BGJ. Microstructure examination, transmission electron microscopy (TEM) and laser diffraction analysis of BGJ showed significant change in particle size and distribution. Moreover, TEM of blanched and sonicated samples of BGJ also showed significant (P⩽0.05) change in microbial profile.

Influence of juice processing factors on quality of black chokeberry pomace as a future resource for colour extraction

Aronia melanocarpa berries are a rich source of anthocyanins and its pomace, a by-product of juice processing, could be efficiently used for extraction of natural colours for the food industry. This study evaluated the influence blanching, freezing, maceration temperatures (2°C, 50°C) and enzyme treatments before juice pressing on the yield and anthocyanin composition of both juice and pomace. Total anthocyanin levels in pomace were affected mostly by enzyme treatment followed by maceration temperature. The pre-heating of the mash prior to processing increased juice yield and retention of anthocyanins in the pomace. Cold maceration of frozen berries without enzyme addition gave the highest concentrations of anthocyanins in the pomace, and both cold and hot maceration of fresh unblanched berries with enzyme the lowest. The results support future exploitation of natural colours from pomace side streams of Aronia, thus increasing competitiveness of Aronia berry production.

Violet-red discolouration of canned Palmyra palm during processing

The objectives of the research were to investigate the causes of the violet-red discolouration during processing of canned Palmyra palm and to identify preventive methods without the use of chemical additives. Palmyra palm flesh with (13-21 %) /without some peel left on was tested for the source of violet-red discolouration during blanching. It was found that blanching in distilled water had no effect on discolouration when blanching conditions were at 75, 85, and 95 °C for 7 min but the violet-red discolouration occurred only when tap water was used for blanching at 95 °C for 7 min. Moreover, the addition of bicarbonate (NaHCO3) in distilled water to imitate higher alkalinity of tap water during blanching could contribute to the violet-red discolouration. Thus the observed cut off alkalinity of the blanching water wherein not to expect any discolouration was found to be about 100 ppm. After sterilization, there was no violet-red discolouration from Palmyra palm flesh without any peel left on even though it had a preceding treatment of blanching in highly alkaline tap water.

Influence of different blanching methods on colour, ascorbic acid and phenolics content of broccoli

Lack of nutrients in cooking water, high energetic costs, high water consumption and recycling are some drawbacks of vegetable blanching. Those disadvantages could be bypassed using microwave blanching. Three blanching methods (microwave, boiling water and steaming) were compared in this study in order to determine their effects on some functional properties of broccoli. In addition, the thermal damage on broccoli colour was evaluated. The effectiveness of each blanching process was performed measuring the lost of peroxidase activity, that results more rapidly in microwaves and steam treatments (50 and 60 s respectively) than in boiling water treatment (120 s). The colour indexes did not allow to discriminate a significant difference among treatments. The increase of treatment time caused a vitamin C decrease in samples blanched by boiling water and steam; this trend was not observed in microwaved samples. The phenols content did not significantly vary depending both on type and on time of treatment.

Effect of pre-treatments and drying methods on quality attributes of sweet bell-pepper (Capsicum annum) powder

Pre-treatments and methods of drying for producing good quality dried bell pepper powder for use in the ready-to-eat (RTE) food products were optimized. Out of various pre-treatments used (blanching in boiling water, KMS, CA and combination of KMS + CA at different concentrations), soaking of bell pepper shreds in KMS@ 0.20 % + CA@ 0.50 % after blanching fasten the drying process (19.75 h) compared to control (22.60 h), when dried in mechanical dehydrator at 58 ± 2 °C. Blanching prior to drying improved the rate of drying and produced product with lower acidity (1.25 %). The samples (T7) treated with KMS@ 0.20 % + CA@ 0.50 % significantly (p < 0.05) retained the ascorbic acid content (47.75 mg/100 g) and also attained highest score for colour (8.0), texture (7.5) and overall acceptability (7.5) compared to rest of the treatments. Among different methods of drying, pre-treated bell peppers dried in solar poly tunnel drier produced bright red coloured powder with relatively higher amounts of sugars and ascorbic acid content, hence was optimized. Visual lump formation was observed at 19.75 % and 18.50 % critical moisture contents, which equilibrated at 42 % and 45 % RH for bell pepper powders dried in a mechanical dehydrator and solar poly tunnel drier, respectively.

Rehydration characteristics of dehydrated West African pepper (Piper guineense) leaves

The rehydration characteristics of dehydrated West African pepper leaves were investigated at hydration temperatures of 28, 60, 70, and 80°C. Four treatments were given to the leaves: blanched and sun dried, unblanched and sun dried, blanched and shade dried, and unblanched and shade dried. The hydration process of the dehydrated leaves was adequately described by the Peleg's equation. As the hydration temperature increased from 28 to 70°C, there was a significant decrease in the Peleg's constant K₁, while for most of the leaves the Peleg's constant K₂ varied with temperature. Rehydration ratio values ranged from 3.75 in blanched shade dried leaves to 4.26 in unblanched sun dried leaves with the unblanched leaves generally exhibiting higher ratios than the blanched leaves.

Blanching, salting and sun drying of different pumpkin fruit slices

The study was aimed at assessing the quality of pumpkin (Cucuribita Spp.) slices that were subjected to pre-drying treatments and drying using two drying methods (uncontrolled sun and oven) fruit accessions. Pre-drying had significant (P ≤ 0.05) effect on the quality of dried pumpkin slices. 10 % salt solution dipped pumpkin fruit slices had good chemical quality. The two-way interaction between drying methods and pre-drying treatments had significant (P ≤ 0.05) effect on chemical qualities. Pumpkin subjected to salt solution dipping treatment and oven dried had higher chemical concentrations. Among the pumpkin fruit accessions, pumpkin accession 8007 had the superior TSS, total sugar and sugar to acid ratio after drying. Among the three pre-drying treatment, salt solution dipping treatment had significant (P ≤ 0.05) effect and the most efficient pre-drying treatment to retain the quality of dried pumpkin fruits without significant chemical quality deterioration. Salt dipping treatment combined with low temperature (60 °C) oven air circulation drying is recommended to maintain quality of dried pumpkin slices. However, since direct sun drying needs extended drying time due to fluctuation in temperature, it is recommended to develop or select best successful solar dryer for use in combination with pre-drying salt dipping or blanching treatments.

Effect of blanching on thin layer drying kinetics of aonla (Emblica officinalis) shreds

The effect of hot water blanching treatment on thin layer drying kinetics of aonla shreds was studied at drying air temperatures of 50, 55 and 60 °C with the air velocity of 1.2 m/s. The drying time decreased with the increase in air temperature and blanching. The drying process was observed in falling rate. Drying after blanching reduced the vitamin C content of aonla shreds by 69.36% whereas it decreased by 27.78% in unblanched shreds. Eight commonly used mathematical models were evaluated to predict the drying behavior of aonla shreds. The Midilli model described the drying behaviour of unblanched aonla shreds at all temperatures better than other models whereas two-term model described the drying kinetics of blanched aonla shreds satisfactorily. The effective diffusivities of the unblanched and blanched aonla shreds were determined using Fick's law of diffusion. The activation energy was found to be 47.21 kJ/mol for unblanched and 43.98 kJ/mol for blanched aonla shreds.

Textural and sensory properties of trifoliate yam (Dioscorea dumetorum) flour and stiff dough 'amala'

The use of trifoliate yam (Dioscorea dumetorum) flour for stiff dough 'amala' production is one of the ways to curb under-utilization of the tuber. The study evaluates the textural and sensory properties of trifoliate yam flour and stiff dough. Freshly harvested trifoliate yam tubers were peeled, washed, sliced and blanched (60 (°)C for 10 min). The sliced yam were soaked in water for 12 h, dried and milled into flour. Pasting viscosities, functional properties, brown index and sensory attributes of the flour and stiff dough were analyzed. Peak, holding strength and final viscosities ranged from 84.09 to 213.33 RVU, 81.25 to 157.00 RVU and 127.58 to 236.17 RVU respectively. White raw flour had higher viscosity than the yellow flours. The swelling index, water absorption capacity and bulk density ranged from 1.46 to 2.28, 2.11 to 2.92 ml H2O/g and 0.71 to 0.88 g/cm(3) respectively. Blanching method employed improved the swelling index and water absorption capacity of flour. The brown index values of flour and stiff dough ranged from 6.73 to 18.36 and 14.63-46.72 respectively. Sensory evaluation revealed significant differences in the colour, odour and general acceptability of the product when compared with the stiff dough from white yam.

Effect of processing methods on the chemical composition of Vitex doniana leaf and leaf products

Fresh leaves of Vitex doniana were subjected to different food processing methods such as drying, blanching and drying, fermentation of the leaf extract as well as blanching and fermentation of the leaf extract. The proximate composition, mineral and vitamin contents of the fresh and processed leaves were subsequently determined, using standard methods. The results shows that V. doniana leaf and products had the following ranges of proximate parameters: 0.07-17.29% protein, 1.85-6.33% fiber, 0.47-6.55% ash, 10.86-95.67% moisture, 0.05-1.29% fat, and 3.61-58.08% carbohydrate. The level of micronutrients detected were generally high and ranged as follows: minerals - Ca (13.38-59.50 mg/100 g), Fe (3.0-18.00 mg/100 g), Na (0.37-1.29 mg/100 g), and vitamins C (1.5-32.98 mg/100 g), A (54.6-3583.26 IU), E (3.11-53.36 mg/100 g), and B₂ (0.01-9.63 mg/100 g). However, the various processing methods used led to significant (P < 0.05) decrease of micronutrients in the extracts, while it caused significant (P < 0.05) increase in the protein, fat, and ash content of the oven-dried sample.

Inhibition of α-amylase and α-glucosidase activities by ethanolic extract of Telfairia occidentalis (fluted pumpkin) leaf

OBJECTIVE

To investigate the inhibitory effect of Telfairia occidentalis Hook f. (Curcubitaceae) (T. occidentalis) leaf on key enzyme linked to type-2 diabetes (α - amylase and α - glucosidase) as well as assess the effect of blanching (a commonly practiced food processing technique) of the vegetable on these key enzymes.

METHODS

Fresh leaves of T. occidentalis were blanched in hot water for 10 minutes, and the extracts of both the fresh and blanched vegetables were prepared and used for subsequent analysis. The inhibitory effect of the extract on α - amylase and α - glucosidase activities as well as some antioxidant parameter was determined in vitro.

RESULTS

The result revealed that unprocessed T. occidentalis leaf reduce Fe(3+) to Fe(2+) and also inhibited α - amylase and α - glucosidase activities in a dose dependent manner. However, blanching of the leafy vegetables caused a significant (P<0.05) increase in the antioxidant properties but decrease their ability to inhibit α - amylase and α - glucosidase activities.

CONCLUSIONS

This antioxidant properties and enzyme inhibition could be part of the mechanism by which they are used in the treatment/prevention of type-2 diabetes. However, the blanched vegetable reduces their ability to inhibit both α - amylase and α - glucosidase activity in vitro.

Inhibitory effect of some tropical green leafy vegetables on key enzymes linked to Alzheimer's disease and some pro-oxidant induced lipid peroxidation in rats' brain

This study sought to investigate the inhibitory effect of some commonly consumed Nigerian green leafy vegetables (raw and blanched) on acetylcholinesterase and butyrylcholinesterase (key enzyme linked to Alzheimer's disease) activities and some pro-oxidants (FeSO4, Sodium nitroprusside and Quinolinic acid) induced lipid peroxidation in rat brain in vitro. Three commonly consumed green leafy vegetables in Nigeria [Amarantus cruentus (Arowojeja), Struchium sparganophora (Ewuro-odo) and Telfairia occidentalis (Ugwu] were blanched in hot water for 10 min, and the extracts of the raw and blanched vegetables were prepared and used for subsequent analysis. The result revealed that all the vegetables inhibited acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity as well as the pro-oxidants induced lipid peroxidation in rat brain in a dose dependent manner; however, Amarantus cruentus extract (EC50 = 97.9 μg/ml) had the highest inhibitory effect on acetylcholinesterase activity while Telfairia occidentalis extract (EC50 = 52.7 μg/ml) had the highest inhibitory effect on butyrylcholinesterase activity. However, blanching of the vegetables caused a significant (P < 0.05) decrease in the inhibitory effect of the vegetables on AChE activities while it enhanced the inhibition of the pro-oxidants induced lipid peroxidation in rat brain in vitro. Therefore, some of the possible mechanism by which green leafy vegetables exert their neuroprotective activities could be through the inhibition of acetylcholinesterase and butyrylcholinesterase activities and prevention of lipid peroxidation in the brain. However, blanching of the vegetables could reduce their ability to inhibit acetylcholinesterase and butyrylcholinesterase activity.

Effect of pretreatment and drying methods on quality of value-added dried aonla (Emblica officinalis Gaertn) shreds

Value added dried Indian gooseberry (aonla) shreds were prepared using aonla fruits of cv. 'NA-7'. Two blanching methods (hot water and potassium metabisulphite (KMS) at 0.1%) and two drying methods (solar and hot air oven drying) were tried for the production of aonla shreds. Common salt, black salt and ginger juice were mixed for enhancing sensory quality of the product. The best product was obtained with KMS blanching and drying in solar dryer with added common salt at 3%. The most acceptable product had ascorbic acid content 298.3 mg/100 g, tannin 2.4%, acidity 2.6%, reducing sugar 3.0%, non-reducing sugar 21.0% and total sugar 24.0%. The recovery was 8.0-8.5%.

Enzymatic treatment of peanut kernels to reduce allergen levels

This study investigated the use of enzymatic treatment to reduce peanut allergens in peanut kernels as affected by processing conditions. Two major peanut allergens, Ara h 1 and Ara h 2, were used as indicators of process effectiveness. Enzymatic treatment effectively reduced Ara h 1 and Ara h 2 in roasted peanut kernels by up to 100% under optimal conditions. For instance, treatment of roasted peanut kernels with α-chymotrypsin and trypsin for 1-3h significantly increased the solubility of peanut protein while reducing Ara h 1 and Ara h 2 in peanut kernel extracts by 100% and 98%, respectively, based on ELISA readings. Ara h 1 and Ara h 2 levels in peanut protein extracts were inversely correlated with protein solubility in roasted peanut. Blanching of kernels enhanced the effectiveness of enzyme treatment in roasted peanuts but not in raw peanuts. The optimal concentration of enzyme was determined by response surface to be in the range of 0.1-0.2%. No consistent results were obtained for raw peanut kernels since Ara h 1 and Ara h 2 increased in peanut protein extracts under some treatment conditions and decreased in others.

Effect of open air drying, LPG based drier and pretreatments on the quality of Indian gooseberry (aonla)

The aonla fruits (whole fruit, pricking, splits, segments) were subjected to pretreatments like blanching, osmotic dehydration with salt (2%) and sugar (40%) in different experiments before drying to obtain a product with better keeping quality. An LPG based drier (CRIDA drier) with capacity to dry 50 kg of fresh Indian gooseberry (aonla) was used. Nutritional quality and rehydration characteristics of CRIDA drier dried products were higher and free from contamination. Drying time was shortest for blanched and osmotically dehydrated segments dried in CRIDA drier and the product had better vitamin C retention, rehydration characteristics and sensory acceptability compared to sun or cabinet drier dried product. The additional expenditure spent on gas in CRIDA drier is compensated by reduced labour cost and higher price for the better quality product. Alternate energy sources like biogas and biomass can be used as fuel in the CRIDA drier.

Effects of pretreatments and salt concentration on rohu (Labeo rohita) roes for preparation of roe pickle

In India, fish egg (roes) is the underutilized rich source of protein and essential fatty acids. An attempt was made to utilize the roes for the preparation of pickle product. Roes of rohu (Labeo rohita) were subjected to pretreatments such as pasteurization and blanching in varying molar concentrations of salt solutions to improve the texture and sensory quality. Losses in protein content and absorption of salt by roes were assessed in both pasteurized and blanched roes for processing them into roe pickle. The pasteurized roes were very soft coupled with high fishy odour. Roes blanched in 1M NaCl solution were found to be good in taste in terms of salt, minimum loss in protein content and reduced fishy odour. The blanched roes were used to prepare fish roe pickle. The pickle was analyzed for physico-chemical parameters, microbial and sensory quality during storage. The roe pickle packed in glass bottle was shelf-stable and scored good for sensory characteristics of flavour, texture, taste and overall acceptability during a storage period of 6 months at room temperature (28 ± 2°C).