Volatile Flavor Compounds of Sweetened Condensed Milk

Addressing flavor challenges in reduced-fat dairy products: A review from the perspective of flavor compounds and their improvement strategies

In recent years, the demand for reduced-fat dairy products (RFDPs) has increased rapidly as the health risks associated with high-fat diets have become increasingly apparent. Unfortunately, lowering the fat content in dairy products would reduce the flavor perception of fat. Fat-derived flavor compounds are the main contributor to appealing flavor among dairy products. However, the contribution of fat-derived flavor compounds remains underappreciated among the flavor improvement factors of RFDPs. Therefore, this review aims to summarize the flavor perception mechanism of fat and the profile of fat-derived flavor compounds in dairy products. Furthermore, the characteristics and influencing factors of flavor compound release are discussed. Based on the role of these flavor compounds, this review analyzed the current and potential flavor improvement strategies for RFDPs, including physical processing, lipolysis, microbial applications, and fat replacement. Overall, promoting the synthesis of milk fat characteristic flavor compounds in RFDPs and aligning the release properties of flavor compounds from the RFDPs with those of equivalent full-fat dairy products are two core strategies to improve the flavor of reduced-fat dairy products. In the future, better modulation of the behavior of flavor compounds by various methods is promising to replicate the flavor properties of fat in RFDPs and meet consumer sensory demands.

New Essential Oils from Ecuadorian Gynoxys cuicochensis Cuatrec. and Gynoxys sancti-antonii Cuatrec. Chemical Compositions and Enantioselective Analyses

The present study belonged to an unfunded project, dealing on the systematic description of unprecedented essential oils (EOs), distilled from 12 species of genus Gynoxys Cuatrec. In this very case, the aim was the first chemical and enantiomeric analyses of two volatile fractions, obtained from the leaves of Gynoxys cuicochensis Cuatrec. and Gynoxys sancti-antonii Cuatrec. These EOs were analyzed by GC-MS (qualitatively) and GC-FID (quantitatively), detecting 89 and 60 components from G. cuicochensis and G. sancti-antonii, respectively. Major components for G. cuicochensis EO, on a nonpolar and polar stationary phase, were α-pinene (29.4-29.6%), p-vinylguaiacol (3.3-3.6%), and germacrene D (20.8-19.9%). In G. sancti-antonii EO, the main compounds were α-pinene (3.0-2.9%), β-pinene (12.9-12.1%), γ-curcumene (19.7-18.3%), germacrene D (9.0% on the polar phase), ar-curcumene (5.3% on the polar phase), δ-cadinene (4.1-4.6%), α-muurolol (3.3-2.4%), α-cadinol (3.0% on both columns), and an undetermined compound, of molecular weight 220. In addition to chemical composition, the enantioselective analysis of the main chiral compounds was carried out on two different chiral selectors. In G. cuicochensis EO, (1R,5R)-(+)-α-pinene, (S)-(+)-β-phellandrene, (R)-(-)-piperitone, and (S)-(-)-germacrene D were enantiomerically pure, whereas β-pinene, sabinene, α-phellandrene, limonene, linalool, and terpinen-4-ol were observed as scalemic mixtures. On the other hand, in G. sancti-antonii EO, the pure enantiomers were (1S,5S)-(-)-α-pinene, (1R,5R)-(+)-sabinene, (R)-(-)-β-phellandrene, (S)-(-)-limonene, (1S,2R,6R,7R,8R)-(+)-α-copaene, (R)-(-)-terpinen-4-ol, and (S)-(-)-germacrene D, whereas β-pinene, linalool, and α-terpineol were present as scalemic mixtures. The principal component analysis demonstrated that G. cuicochensis volatile fraction was quite similar to many of the other EOs of the same genus, whereas G. sancti-antonii produced the most dissimilar EO. Furthermore, the enantioselective analyses showed the usual variable enantiomeric distribution, with a greater presence of enantiomerically pure compounds in G. sancti-antonii EO.

Identification of odor-causing compounds in six species of odor-producing microalgae separated from drinking water source with distinct fishy odor: Insight into microalgae growth and odor characteristics

Fishy odor, as an offensive and unpleasant odor, could occur in drinking water source with poor nutrition, it is usually considered to be associated with odor-producing microalgae. However, the specific relations among fishy odor, fishy odorants and responsible microalgae were not elucidated comprehensively. In this paper, the odor-causing compounds generated from six microalgae with fishy odor characteristic, isolated in drinking water source Tongyu River, were identified simultaneously. The sensory evaluation result indicated that Tongyu River was principally related to fishy odor (odor intensity 6.5-7.6). Correspondingly, seven, nine, seven, six, seven and seven olfactory detection peaks (ODP) were screened by combining data of GC/O/MS and GC/GC/TOFMS in Cyclotella, Cryptomonas ovate, Melosira, Dinobryon sp., Synedra and Ochromonas sp., which were isolated in Tongyu River and cultured in laboratory. Totally twenty odor-causing compounds, including hexanal, 2-hexenal, 3-hexen-1-ol, heptanal, 1-octen-3-one, 2,4-heptadienal, 2-tetradecanone, 3,5-octadien-2-one, octanal, 1-octen-3-ol, 2-octenal, nonanal, 2,4-octadienal, 2-nonenal, decanal, 2,6-nonadienal, 2-decenal, undecanal, 2,4-decadienal and dodecanal, were screened and identified in all isolated microalgae. Additionally, fishy odor intensity for all identified microalgae increased obviously as microalgae cell number increased and microalgae cell ruptured in cultivation cycles through pearson and spearman correlation analysis. For the first time, twenty odor-causing compounds associating with fishy odor were recognized from six isolated microalgae, which would provide more scientific basis and theoretical support for preventing and treating fishy odor episode of drinking water source.

Determination and Risk Assessment of Flavor Components in Flavored Milk

This study aimed to determine chemical composition and assess exposure in flavored milk among Chinese residents, based on risk assessment methodologies of acceptable daily intake (ADI) and toxicological concern threshold (TTC). Esters (32.17%), alcohols (11.19%), olefins (9.09%), aldehydes (8.39%), and ketones (7.34%) comprised the majority of the flavoring samples. Methyl palmitate (90.91%), ethyl butyrate (81.82%), and dipentene (81.82%) had the highest detection rates in flavor samples. This study screened fifteen flavor components of concern and discovered that 2,3,5-trimethylpyrazine, furfural, benzaldehyde, and benzenemethanol were detected in 100% of flavored milk samples. Benzenemethanol was found in the highest concentration (14,995.44 μg kg^-1). The risk assessment results revealed that there was no risk for Chinese residents in consuming flavored milk, and the maximum per capita daily consumption of 2,3,5-trimethylpyrazine, furfural, and benzenemethanol were 226.208 g, 140.610 g, and 120.036 g, respectively. This study could provide guidelines for amounts of flavor additive ingredients in milk.

Identification and evaluation of fishy odorants produced by four algae separated from drinking water source during low temperature period: Insight into odor characteristics and odor contribution of fishy odor-producing algae

Disgusting fishy odor could break out inside oligotrophic drinking waterbody in winter with low temperature. Nevertheless, fishy odor-producing algae and corresponding fishy odorants were not very clear, odor contribution of fishy odorant and odor-producing algae to overall odor profile were also not well understood. In this study, the fishy odorants, produced by four algae separated from Yanlong Lake, were identified simultaneously. Odor contribution of identified odorant, separated algae to overall fishy odor profile were both evaluated. The results indicated Yanlong Lake was mainly associated with fishy odor (flavor profile analysis (FPA) intensity: 6), eight, five, five and six fishy odorants were identified and determined in Cryptomonas ovate, Dinobryon sp., Synura uvella, Ochromonas sp., respectively, which were separated and cultured from water source. Totally sixteen odorants with concentration range of 90-880 ng/L, including hexanal, heptanal, 2,4-heptadienal, 1-octen-3-one, 1-octen-3-ol, octanal, 2-octenal, 2,4-octadienal, nonanal, 2-nonenal, 2,6-nonadienal, decanal, 2-decenal, 2,4-decadienal, undecanal, 2-tetradecanone, were verified in separated algae and associated with fishy odor. Although more odorants' odor activity value (OAV) were lower than one, approximately 89%, 91%, 87%, 90% of fishy odor intensities could be explained by reconstituting identified odorants for Cryptomonas ovate, Dinobryon sp., Synura uvella, Ochromonas sp., respectively, suggesting synergistic effect could exist among identified odorants. By calculating and evaluating total odorant production, total odorant OAV and cell odorant yield of separated algae, odor contribution rank to overall fishy odor should be Cryptomonas ovate (28.19%), Dinobryon sp. (27.05%), Synura uvella (24.27%), Ochromonas sp. (20.49%). This is the first study for identifying fishy odorants from four actually separated odor-producing algae simultaneously, this is also for the first time evaluating and explaining odor contribution of identified odorant, separated algae to overall odor profile comprehensively, this study will supply more understanding for controlling and managing fishy odor in drinking water treatment plant.

Sexual Differences in Eurya loquaiana Dunn Floral Scent and How Pollinators Respond

Eurya plants are usually dioecious or subdioecious with small fragrant flowers. Here, we investigate the floral scent components of the subdioecious species Eurya loquaiana Dunn and how floral scent affects pollinators. Headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) was used to compare the floral scents of male, female, and hermaphrodite flowers. We also test whether differences in floral scent affect the foraging behaviors of pollinators and describe the flower morphological traits of the three sexes. Twenty-eight floral scent compounds were tentatively identified, and four monoterpenoids were tentatively identified as the most abundant compounds: linalool oxide (pyranoid), linalool, lilac aldehyde, and linalool oxide (furanoid). There were floral scent differences among the sex types, and male flowers were more attractive to pollinators in the wild, even when visual factors were excluded, indicating that pollinators likely distinguish sexual differences by floral scent. In the competition for pollinators, the advantage that male flowers have over female and hermaphrodite flowers can likely be accounted for the differences in floral scent and display size.

Characterization of functional sweetened condensed milk formulated with flavoring and sugar substitute

In the present study, the effect of sugar replacement and enrichment with cinnamon extract (CE) on the physicochemical, functional, and organoleptic properties of sweetened condensed milk (SCM) and the production of flavored functional dairy dessert was investigated. The results demonstrated that by adding CE (0.5 and 1%) and fructose sugar (50 and 100% replacement) in the formulation containing maltodextrin, the physicochemical, functional, and organoleptic properties of SCM samples were improved. However, adding fructose and CE at the maximum concentration increased the acidity, particle size, redness (a), yellowness (b) and decreased the lightness (L), viscosity, and sensory scores of the SCM samples (p < .05). Scanning electron microscopy images demonstrated that as the fructose level increased, the number of cavities increased, while the size of the cavities decreased (p < .05). Microstructure analysis also showed that the application of CE increased the density of the structure in the SCM samples. However, the SCM samples formulated with maltodextrin, 0.5% CE, and 50% fructose substitution were identified as optimal samples. Evaluation of the functional properties of SCM formulated with 0.5% CE revealed that the total phenolic content (TPC) and DPPH radical scavenging activity were in the range of 139.21-143.24 mg GAE / g and 50.12%-52.01%, respectively.

Identification of fishy odor causing compounds produced by Ochromonas sp. and Cryptomonas ovate with gas chromatography-olfactometry and comprehensive two-dimensional gas chromatography

Disgusting fishy odor problems have become a major concern in drinking water quality, and are commonly related to algal proliferation in source water. Unlike the typical musty/earthy odorants 2-methylisoborneol (MIB) and geosmin, identification of the corresponding fishy odorants is still a big challenge. In this study, two species of fishy-odor-producing algae, Ochromonas sp. and Cryptomonas ovate, were cultured to explore the odor production characteristics and typical odorants. When algae were ruptured in the stationary and decline phases, fishy odor intensities of 4 to 8 characterized by FPA were produced. However, some frequently reported aldehydes that could cause fishy odor, including n-hexanal, 2-octenal, heptanal, 2,4-heptanal and 2,4-decadienal, were not detected in either of the cultured algae. The possible fishy odor-causing compounds were further identified by combining gas chromatography-olfactometry (GC-O/MS) and comprehensive two-dimensional gas chromatography (GC × GC-TOFMS) using retention indices (RIs). From GC-O/MS analysis, twelve and six olfactometry peaks with various odor characteristics were identified in Ochromonas sp. and Cryptomonas ovate, respectively, of which three and two olfactometry peaks showed fishy odor characteristics. 2-Nonenal, 2,4-octadienal, fluorene and 2-tetradecanone were identified as fishy odorants in Ochromonas sp., and 1-octen-3-ol, 6-methyl-5-hepten-2-one, 1-octen-3-one, 2-nonenal and 2,4-octadienal were identified in Cryptomonas ovate. Other identified compounds, including butyl butanoate (fragrant odor), ionone (fragrant odor), bis (2-chloroisopropyl) ether (chemical odor) etc., did not show fishy features. Therefore, the fishy odor might be a synthetic and comprehensive odor, which resulted from the combination of different odorants and their synergistic effects. The results of this study will be helpful for understanding fishy odor problems, which will provide support for fishy odor management and control in the drinking water industry.

Volatile Compounds Produced by Lactobacillus paracasei During Oat Fermentation

This study investigated the profiles of volatile compounds produced by Lactobacillus paracasei during oat fermentation using gas chromatography-mass spectrometry coupled with headspace solid-phase microextraction method. A total of 60 compounds, including acids, alcohols, aldehydes, esters, furan derivatives, hydrocarbons, ketones, sulfur-containing compounds, terpenes, and other compounds, were identified in fermented oat. Lipid oxidation products such as 2-pentylfuran, 1-octen-3-ol, hexanal, and nonanal were found to be the main contributors to oat samples fermented by L. paracasei with the level of 2-pentylfuran being the highest. In addition, the contents of ketones, alcohols, acids, and furan derivatives in the oat samples consistently increased with the fermentation time. On the other hand, the contents of degradation products of amino acids, such as 3-methylbutanal, benzaldehyde, acetophenone, dimethyl sulfide, and dimethyl disulfide, decreased in oat samples during fermentation. Principal component analysis (PCA) was applied to discriminate the fermented oat samples according to different fermentation times. The fermented oats were clearly differentiated on PCA plots. The initial fermentation stage was mainly affected by aldehydes, whereas the later samples of fermented oats were strongly associated with acids, alcohols, furan derivatives, and ketones. The application of PCA to data of the volatile profiles revealed that the oat samples fermented by L. paracasei could be distinguished according to fermentation time.

Short communication: Formation of oxidized flavor compounds in concentrated milk and distillate during milk concentration

Oxidized flavor stability of milk is highly associated with consumer acceptance. This study characterized oxidized flavor stability as affected by milk concentration. The selected volatiles in raw milk (RM), heated milk (HM), concentrated milk, and distillate were investigated using solid-phase microextraction-gas chromatography-mass spectrometry. Concentrated milk and distillate showed higher levels of heptanal (14.52-17.24μg/kg), nonanal (5.08-8.64μg/kg), 2-heptanone (25.22-73.25μg/kg), and 2-nonanone (10.83-17.28μg/kg) compared with RM and HM. Based on the odor activity values of different volatiles, oxidized volatiles may contribute to fatty, greasy, soapy, and dyestuff oxidized odors in concentrated milk. Oxidized volatiles of nonanal, 2-heptanone, and 2-nonanone were found to be higher in concentrated milk at 50°C than at 40°C. In addition, 18 and 24 volatiles were found in unconcentrated milk and distillate, respectively. Straight aldehydes and methyl ketones showed much higher levels in distillate than in RM and HM, which also had higher levels compared with their corresponding concentrated milk samples. These results indicated that oxidized volatiles were mainly evaporated into distillate as flavor loss. They also suggested that lipid oxidation could continue drastically even under the concentration processing at a low temperature and reduced pressure.

Evaluation of the enthalpy of formation, proton affinity, and gas-phase basicity of gamma-butyrolactone and 2-pyrrolidinone by isodesmic reactions

The knowledge of thermochemical parameters such as the enthalpy of formation, gas-phase basicity, and proton affinity may be the key to understanding molecular reactivity. The obtention of these thermochemical parameters by theoretical chemical models may be advantageous when experimental measurements are difficult to accomplish. The development of ab initio composite models represents a major advance in the obtention of these thermochemical parameters, but these methods do not always lead to accurate values. Aiming at achieving a comparison between the ab initio models and the hybrid models based on the density functional theory (DFT), we have studied gamma-butyrolactone and 2-pyrrolidinone with a goal of obtaining high-quality thermochemical parameters using the composite chemical models G2, G2MP2, MP2, G3, CBS-Q, CBS-4, and CBS-QB3; the DFT methods B3LYP, B3P86, PW91PW91, mPW1PW, and B98; and the basis sets 6-31G(d), 6-31+G(d), 6-31G(d,p), 6-31+G(d,p), 6-31++G(d,p), 6-311G(d), 6-311+G(d), 6-311G(d,p), 6-311+G(d,p), 6-311++G(d,p), aug-cc-pVDZ, and aug-cc-pVTZ. Values obtained for the enthalpies of formation, proton affinity, and gas-phase basicity of the two target molecules were compared to the experimental data reported in the literature. The best results were achieved with the use of DFT models, and the B3LYP method led to the most accurate data.

Identification of trace volatile compounds in freshly distilled Calvados and Cognac using preparative separations coupled with gas chromatography-mass spectrometry

Gas chromatography coupled with mass spectrometry (GC-MS) using both electron impact and chemical ionization detection modes led to the determination of the volatile composition of two samples of freshly distilled Cognac and two samples of freshly distilled Calvados. A total of 169 volatile compounds were directly identified in dichloromethane extracts obtained by liquid-liquid extraction. Trace compounds present in both spirits were characterized with the help of preparative separations. In a first step, groups of compounds were separated by preparative GC, and the fractions were analyzed on a polar stationary phase by GC-MS. In a second step, silica gel fractionation was used to separate them by polarity. In this study, 331 compounds, of which 162 can be considered as trace compounds, were characterized in both freshly distilled Cognac and Calvados. Of these, 39 are common to both spirits; 30 are specific to Cognac with numerous hexenyl esters and norisoprenoidic derivatives, whereas 93 are specific to Calvados with compounds such as unsaturated alcohols, phenolic derivatives, and unsaturated aldehydes.