Free Amino Acid Composition Research Articles

Patterns of free amino acids in tundra soils reflect mycorrhizal type, shrubification, and warming

The soil nitrogen (N) cycle in cold terrestrial ecosystems is slow and organically bound N is an important source of N for plants in these ecosystems. Many plant species can take up free amino acids from these infertile soils, either directly or indirectly via their mycorrhizal fungi. We hypothesized that plant community changes and local plant community differences will alter the soil free amino acid pool and composition; and that long-term warming could enhance this effect. To test this, we studied the composition of extractable free amino acids at five separate heath, meadow, and bog locations in subarctic and alpine Scandinavia, with long-term (13 to 24 years) warming manipulations. The plant communities all included a mixture of ecto-, ericoid-, and arbuscular mycorrhizal plant species. Vegetation dominated by grasses and forbs with arbuscular and non-mycorrhizal associations showed highest soil free amino acid content, distinguishing them from the sites dominated by shrubs with ecto- and ericoid-mycorrhizal associations. Warming increased shrub and decreased moss cover at two sites, and by using redundancy analysis, we found that altered soil free amino acid composition was related to this plant cover change. From this, we conclude that the mycorrhizal type is important in controlling soil N cycling and that expansion of shrubs with ectomycorrhiza (and to some extent ericoid mycorrhiza) can help retain N within the ecosystems by tightening the N cycle.

Evaluation of antioxidant and antibacterial activities of fish protein hydrolysate produced from Malaysian fish sausage (Keropok Lekor) by-products by indigenous Lactobacillus casei fermentation

Malaysian fish sausage, Keropok Lekor (KL), is a popular fish snack in Malaysia. The fish by-products (FBPs) from KL processing comprise a significant quantity of proteins with high nutritional value. However, in Malaysia, such FBPs are either disposed of into waterways, which may cause environmental pollution, or are processed into products of low economic value, such as fertiliser and animal feed. To maximise the potential of FBPs, a microbial fermentation approach can be used to convert FBPs into bioactive fish protein hydrolysate (FPH). Bioactive FPH has higher economic value due to its potential as a bio-ingredient in the nutraceutical and functional food industries. This study aimed to evaluate antioxidant and antibacterial activities of FPHs from FBPs of KL processing produced by four indigenous Lactobacillus casei strains (LC216, LC217, LC219, and LC220). The relationship between the level and composition of free amino acids during fermentation and the antioxidant and antibacterial activities of the produced FPH was evaluated. The results showed that the FPHs produced using the four L. casei strains had higher 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities (82.8–88.4%) than that of the unfermented FBPs (78.9%). The obtained half-maximal effective concentrations (EC50) of the FPHs were also significantly lower (p < 0.05) than those of the unfermented FBPs. The ferrous chelating ability of the FPHs produced using strain LC217 improved by 68.43% compared to that of the unfermented FBPs. Furthermore, compared to the unfermented FBPs, the FPHs produced using strains LC216 and LC217 had a significantly higher (p < 0.05) maximum growth inhibition against Listeria monocytogenes, Salmonella typhimurium, Escherichia coli and Listeria innocua. Moreover, there was a positive relationship between the degree of hydrolysis and the bioactivities. A strong positive correlation also existed between the level of antioxidant amino acids content and antioxidant activity. Overall, the L. casei fermentative production of bioactive FPHs from the FBPs from KL processing represents an effective, environmentally sustainable and economical strategy for producing bioactive bioingredients, which can be used in functional food production and food preservation.

Changes in the free amino acid profile of pickling cucumber during lactic acid fermentation.

Free amino acid (FAA) profiles of fresh, acidified, naturally fermented, and starter culture fermented cucumbers were analyzed by liquid chromatography triple quadrupole mass spectrometry. Fermented cucumbers contained more total FAA than acidified cucumbers (1,302 ± 102mg/kg and 635 ± 35mg/kg, respectively). Total FAA content of fermented cucumber was similar regardless of brine salt levels (2-6% NaCl) and starter culture addition. Glutamine (1491.4± 69.3mg/kg), γ-aminobutyric acid (GABA, 269.6± 21.4mg/kg), asparagine (113.0± 6.4mg/kg), and citrulline (110.3±8.5mg/kg) were the most abundant FAA in fresh pickling cucumber, whereas GABA (181.3±21.5mg/kg), isoleucine (165.2± 11.2mg/kg), leucine (129.8± 10.9mg/kg), and lysine (110.9± 5.0mg/kg) were the most abundant in fermented cucumber. GABA and ornithine were produced during fermentation, indicating glutamate decarboxylase and arginine deiminase activities. Notably, ornithine was significantly higher in natural (63.3±31.5mg/kg) versus starter culture fermented cucumbers (3.0±0.7mg/kg). This new information on FAA composition of fresh and fermented pickling cucumbers shows the impact of fermentation conditions on cucumber amino acid profiles while providing insight for manipulating fermentations for health promotion and consumer acceptance. PRACTICAL APPLICATION: This study reports changes in the free amino acid profiles of raw, fermented and acidified cucumbers, which may be valuable for understanding the impact of these foods on human health and nutrition. This information is useful for food microbiologists studying the metabolism of lactic acid bacteria during fermentation and/or designing starter cultures and could contribute to the development of novel fermented cucumber pickle products with enhanced nutritional value.

Monitoring of the yogurt fermentation process based on a rapid bio-luminescent chiral pattern recognition of amino acids.

The analysis of chiral α-amino acids is of great significance in asymmetric synthesis, nutrition, food science, and microbiology. However, the ability of chiral recognition is difficult to achieve. Due to the demand for expensive equipment and skilled operators, traditional methods such as high-performance liquid chromatography are limited. The previously reported methods based on chemical sensor arrays usually cannot carry out the chiral analysis. Here, we developed a novel biosensor array based on the interaction between a suite of host-based luminescent bacteria and amino acids and used linear discriminant analysis to reflect their luminescence response patterns. This biosensor array could effectively discriminate chiral amino acids, including 19 L-amino acids, their corresponding D-enantiomers, and the achiral glycine. In addition, the determination of enantiomeric purity and quantitative ability has been proved. The successful identification of a complex system containing multiple chiral amino acids further demonstrates the superiority of the bioluminescent sensor array. Moreover, this sensor array could efficiently monitor the dynamic composition of free amino acids in the process of milk fermentation. Finally, the bioluminescence response mechanism of the luminescent bacteria for the recognition of chirality was clarified. This approach possessed the advantages of facile construction, high throughput, easy operation, high accuracy and fast response.

Composition of Free Amino Acids in Fermented Honey, an Untapped Resource from Japanese Honeybees

Composition of Free Amino Acids in Fermented Honey, an Untapped Resource from Japanese Honeybees

Revealing of free radical scavenging and angiotensin I-converting enzyme inhibitor potency of pigmented rice seed protein

The potential source of bioactive protein from pigmented rice seed was investigated by buffered extracting from nine varieties (Merah-SP, Gogo Niti-2, Merah Wangi, Super Manggis, Lamongan-1, Mota, Ketan Hitam-2, Beureum Taleus, and Aek Sibundong) and non-pigmented rice (IR-64) as a control. The potent contributor to free radical scavenging of extracted proteins was evaluated by analyzing their free amino acid composition. The free radical scavenging and angiotensin-I converting enzyme (ACE-I) inhibitory activity of these proteins were analyzed in-vitro. The free radical scavenging activity was analyzed using various standard methods, including radical cation 2,2-azinobis-3-ethylbenzothiazoline-6-sulphonate acid (ABTS•+), hydroxyl radical (OH•) and defense against radical-mediated DNA damages by hydroxyl. Total free amino acid content ranged between 77.7-181.2 g/100 g protein, and among them, Ketan Hitam-2 displayed the highest abundant antioxidant amino acid grouping (23.23%) and shown significantly higher ABTS•+ activity (IC50=8.64 µg/mL) and OH• activity (IC50=20.33 µg/mL). Moreover, Ketam Hitam-2 also exhibited notable ACE-I inhibitory activity (IC50=6.20 µg/mL) and protected hydroxyl-induced oxidative damage to DNA. The in-vitro systems for free radical scavenging and ACE-I inhibitory were used to acquire the data. The potency of Ketan Hitam-2 seed protein could be utilized as a natural nutraceuticals compound.

Fish muscle hydrolysate obtained using largemouth bass Micropterus salmoides digestive enzymes improves largemouth bass performance in its larval stages.

The present study utilized digestives tracts from adult largemouth bass (LMB) to hydrolyze Bighead carp muscle and obtain an optimal profile of muscle protein hydrolysates that would be easily assimilated within the primitive digestive tract of larval LMB. Specifically, muscle protein source was digested for the larva using the fully developed digestive system of the same species. The objectives of this study were: 1) to develop an optimal in vitro methodology for carp muscle hydrolysis using LMB endogenous digestive enzymes, and 2) to evaluate the effect of dietary inclusion of the carp muscle protein hydrolysate on LMB growth, survival, occurrence of skeletal deformities, and whole-body free amino acid composition. The study found that the in vitro hydrolysis method using carp intact muscle and LMB digestive tracts incubated at both acid and alkaline pH (to mimic digestive process of LMB) yielded a wide range of low molecular weight fractions (peptides), as opposed to the non-hydrolyzed muscle protein or muscle treated only with acid pH or alkaline pH without enzymes from LMB digestive tracts, which were comprised of large molecular weight fractions (polypeptides above 150 kDa). Overall, the dietary inclusion of the carp muscle hydrolysate improved growth performance of larval LMB in terms of final average weight, weight gain, DGC, SGR, and body length after 21 days of feeding compared to fish that received the diet based on non-hydrolyzed carp muscle. The study also found that hydrolysate-based feed significantly reduced skeletal deformities. The positive growth performance presented by fish in the hydrolysate-fed group possibly resulted from matching the specific requirements of the larvae with respect to their digestive organ development, levels of digestive enzymes present in the gut, and nutritional requirements.

Effects of low salinity on fatty acid and free amino acid composition of muscle tissues in Portunus trituberculatus

The effects of low salinity on fatty acid and free amino acid (FAA) composition in muscles of swimming crab, Portunus trituberculatus, were investigated in this study. The swimming crabs were reared for 5 weeks under two different experimental treatments (the 12 ppt group and the 24 ppt group). Then, composition of fatty acids and free amino acids in total muscles was measured using gas chromatography–mass spectrometry (GC-MS) with external standard method and liquid chromatography–mass spectrometer (LC-MS) with internal standard method respectively. Results of fatty acid analysis showed that C18:1n9c, C20:5n3 (EPA) and C22:6n3 (DHA) were the dominating fatty acids in muscle tissues of P. trituberculatus. There was an extremely significant increase in contents of total fatty acids (TFA), total saturated fatty acids (SFA), total monounsaturated fatty acid (MUFA) and total polyunsaturated fatty acid (PUFA) in muscle tissues of P. trituberculatus with low salinity treatment (12 ppt) compared with those cultured in seawater (24 ppt) (p < 0.01). Results of free amino acid analysis showed that the content of total free amino acids (TFAA) significantly decreased in muscle tissues of P. trituberculatus with low salinity treatment compared with those in seawater (p < 0.05). Among all flavour-tasting FAAs, the umami FAA content was extremely significantly higher in low salinity group compared with control group (p < 0.01); the sweetish FAA content was significantly lower in low salinity group while the bitter taste of FAA content had no significant differences between two groups.

Influence of diesel fuel on the composition and content of free amino acids in the green alga Acrosiphonia arcta

Arctic ecosystems are the most sensitive and vulnerable to anthropogenic impact, namely, the influence of petroleum products. The aim is to identify the effect of diesel fuel (DF) on the composition of free amino acids (FAA) in Acrosiphonia arcta in Barents Sea. The impact of DF concentrations of 20 - 3000 maximal permitted concentration (MPC) was analyzed. It was found that A. arcta contains 20 amino acids, 16 of which are proteinogenic and 8 are essential. The composition of the FAA pool did not change under the influence of DF, but the content of individual FAA and their total amount differed. The ratio of the dominant amino acids changes: at concentrations of DF up to 1000 MPC content of proline increased, and decreased at higher concentrations of DF. Under the influence of DF in concentration of 3000 MPC, taurine content significant increased. The least negative effect was exerted under the influence of DF concentration of 20 MPC, more significant - at the concentration more than 1000 MPC. Changes in the content of FAA are probably associated with the redirection of the synthesis pathways of amino acid groups, as well as the inhibitory effect of the toxicant on protein synthesis.

Effect of different thermal processing methods on water-soluble taste substances of tilapia fillets

The composition of free amino acids (FAAs) and nucleotides has an important effect on fish taste. In this study, the content of FAAs and nucleotides in raw, steamed, boiled and air-fried tilapia fillets were quantitatively analyzed. Thermal processing significantly influenced the composition of FAAs and nucleotides in tilapia. Moreover, there were substantial differences in the nutritional composition of tilapia processed by steaming, boiling and air frying. Compared with raw fillets, the total FAA (TFAA) increased after steaming, boiling, and air frying. The main umami and sweet amino acids in tilapia fillets were aspartic acid and glycine. The total nucleotide content of fresh tilapia was 299 mg/100 g, which increased to 305 and 366 mg/100 g after steaming and air frying, respectively, and decreased to 273 mg/100 g after boiling. The main taste nucleotide inosine monophosphate (IMP) with a taste activity value greater than 1, contributed greatly to the taste of tilapia. Equivalent umami concentration was used for taste evaluation: air frying > steaming > boiling. Therefore, our findings establish that the water-soluble taste substances of tilapia fillets, and the mutual regulatory effects of different compounds varied with different thermal processing methods. Hence, tilapia can be thermally processed according to different taste requirements.

Tissue-specific distribution of primary and secondary metabolites of Baemoochae (×Brassicoraphanus) and its changes as a function of developmental stages

The distribution and changes in the primary and secondary metabolite profiles of Baemoochae, an inter-generic hybrid of Chinese cabbage and radish, during the plant’s developmental stages were investigated. Metabolites were analyzed using gas chromatography-mass spectrometry (GC-MS) and ultra-high-performance liquid chromatography-electrospray ionization-quadrupole time-of-flight (UHPLC-ESI-qTOF MS). Free sugar, organic acid, and amino acid composition depended on the tissue type and developmental stage of Baemoochae. For example, glucose and alanine levels were higher in mature leaves than in young leaves; citric acid content in mature roots was lower than that in young roots. Several glucosinolates were identified for the first time in Baemoochae. Glucoraphasatin was predominant in both leaves and roots, regardless of plant maturity. Total glucosinolate content was significantly higher in roots than in leaves and in mature than in young plants. The roots of mature Baemoochae could be used as a rich source of glucosinolates, with several potential health-promoting effects.

Use of Rapid Capillary Zone Electrophoresis to Determine Amino Acids Indicators of Herring Ripening during Salting.

Currently, herring fillets are salted with acetic acid to activate muscle proteases. This causes a change in the composition of free amino acids, compared to salting of whole fish with viscera proteases. Therefore, old indicators of the ripening dynamics of salted fish based on amino acids are not current. Determination of free amino acids can be performed by many methods, but most are labor intensive and expensive. Therefore, a capillary electrophoresis method without derivatization (CZE) was used to determine the actual ripening rates of salted herring fillets. A group of hydrophobic and basic amino acids were determined in trichloroacetic acid (TCA) extracts of meat and brine to develop 16 indicators. Statistical regression analysis of the indicators (R2adj, RMSE, cluster analysis) followed by principal component analysis (PCA) correlation analysis of the indicators vs sensory evaluation parameters of texture and TPA-hardness of salted fillet meat allowed the choice of the most precise indicators. The best indicator in meat was Phe/Tyr-height, which value increased during salting. A more precise indicator of ripening was His/Tyr-height in brine, which value decreased during salting. Sensory evaluation parameters of salted herring texture correlated strongly with TPA-hardness and traditional indicators such as non-protein nitrogen and protein hydrolysis product fraction content. However, the most precise indicators were those obtained from amino acids determined by the CZE method. Results obtained in this study may be suitable for fast monitoring of the salted herring ripening process in industry.

Composition and nutritional qualities of edible tissues of Chinese mitten crab (Eriocheir sinensis) from Ya Lake over different months

The edible tissue yield, proximate, fatty acid, and free amino acid composition were examined and compared among Chinese mitten crabs (Eriocheir sinensis) samples from Ya Lake over different months. Regardless of gender, the gonadosomatic index (GSI) was higher in May and June than that in August and September (P < 0.05), whereas the hepatopancreas index (HSI), meat yield (MY), and total edible yield (TEY) were higher in August and September. For proximate composition, regardless of gender, the total lipid content in the hepatopancreas was significantly higher in September than in other months, and the total lipid and protein content in the gonads was the highest. Furthermore, the content of EPA in female hepatopancreas was the highest in August. Regardless of sex, C16:1n7 in muscle was higher in September than in other months (P < 0.05), and the ratio of n-3/n-6 PUFA was the highest. Moreover, females had the highest glutamate and arginine content in their ovaries in August (P < 0.05). Among the muscles, both sexes contained higher levels of alanine and glutamate in September. Thus, the edible tissue yield, nutritional quality, and taste of Ya Lake E. sinensis in September were the best.

Free threonine in human breast milk is related to infant intestinal microbiota composition

BackgroundAccumulating evidence indicates that free amino acids (FAA) might be bioactive compounds with potential immunomodulatory capabilities. However, the FAA composition in human milk is still poorly characterized with respect to its correlation to maternal serum levels and its physiological significance for the infant. Studies addressing the relation of human milk FAA to the infants' intestinal microbiota are still missing.MethodsAs part of a pilot study, maternal serum and breast milk FAA concentrations as well as infant intestinal microbiota (16S rRNA) were determined 2 months after birth. The study cohort consisted of 41 healthy mothers and their term delivered, healthy infants with normal birthweight. The relationship between maternal serum and milk FAA was determined by correlation analyses. Associations between (highly correlated) milk FAA and infant intestinal beta diversity were tested using PERMANOVA, LefSe and multivariate regression models adjusted for common confounders.ResultsSeven breast milk FAA correlated significantly with serum concentrations. One of these, threonine showed a negative association with abundance of members of the class Gammaproteobacteria (R2adj = 17.1%, p = 0.006; β= − 0.441). In addition, on the level of families and genera, threonine explained 23.2% of variation of the relative abundance of Enterobacteriaceae (R2adj; p = 0.001; β = − 0.504) and 11.1% of variability in the abundance of Escherichia/Shigella (R2adj, p = 0.025; β = − 0.368), when adjusted for confounders.ConclusionOur study is the first to suggest potential interactions between breast milk FAA and infant gut microbiota composition during early lactation. The results might be indicative of a potential protective role of threonine against members of the Enterobacteriaceae family in breast-fed infants. Still, results are based on correlation analyses and larger cohorts are needed to support the findings and elucidate possible underlying mechanisms to assess the complex interplay between breast milk FAA and infant intestinal microbiota in detail.

Effects of microbial coagulants from Rhyzomucor miehei on composition, sensory and textural characteristics of long-ripened hard cheeses

The increasing use of rennet substitutes entails evaluating their performances on different types of cheese. The production of hard cheese using either microbial coagulants from Rhyzomucor miehei (MC) or calf rennet (CR) from different manufacturers was investigated in parallel cheese makings at three industrial dairies. Cheeses were analysed after 9, 12, 16 and 18 months of ripening. Minor differences in cheese composition were found between treatments, principally related to fat content. Cheeses produced with one out of the three MC showed slower primary proteolysis on both αs1- and αs0-casein, compared to the corresponding CR cheeses, indicating a different activity of this coagulant. The same cheeses also had significantly different sensory profiles at 9 months of ripening. Treatments did not differ in free amino acid composition nor in rheological parameters, regardless of ripening period. The long ripening of hard cheeses thus smooths possible differences attributable to MC.

Silencing of a putative alanine aminotransferase (ALT) gene influences free amino acid composition in hemolymph and fecundity of the predatory bug, Cyrtorhinus lividipennis Reuter.

In Asian rice systems, Cyrtorhinus lividipennis Reuter is an important predator that preys on rice planthopper eggs and young nymphs, as a primary food source. Alanine aminotransferase (ALT) acts in many physiological and biochemical processes in insects. We cloned the full-length complementary DNA of C. lividipennis ClALT. Expression analysis showed higher expression in the fat body and midgut compared to other tissues. It is expressed in all C. lividipennis developmental stages and at least four organs. Silencing of ClALT by RNA interference significantly decreased the ClALT enzyme activity and ClALT expression compared to dsGFP-treated controls at 2 days after emergence (DAE). Silencing of ClALT influenced free hemolymph amino acid compositions, resulting in a reduction of Aspartic acid (Asp) and Alanine (Ala) proportions, and increased Cysteine (Cys) and Valine (Val) proportions in females at 2 DAE. dsClALT treatments led to decreased soluble total protein concentrations in ovary and fat body, and to lower reduced vitellogenin (Vg) expression, body weight, and the numbers of laid eggs. The double-stranded RNA viruse treatments also led to prolonged preoviposition periods and hindered ovarian development. Western blot analysis indicated that silencing ClALT also led to reduced fat body Vg protein abundance at 2 DAE. These data support our hypothesis that ClALT influences amino acid metabolism and fecundity in C. lividipennis.

Differential response of the accumulation of primary and secondary metabolites to leaf‐to‐fruit ratio and exogenous abscisic acid

Background and Aims Climate change is modifying grape berry composition and affecting wine quality and typicity. We evaluated the effects of leaf-to-fruit ratio and exogenous abscisic acid (ABA) application on the accumulation of primary and secondary metabolites in berries, in order to optimise climate change adaptation strategies. Methods and Results A range of leaf-to-fruit ratios (2, 4, 6, 8, 10 or 12 leaves per bunch) and exogenous ABA (400 mg/L) applied to Vitis vinifera L. cv. Cabernet Sauvignon fruiting-cuttings in a greenhouse prior to veraison were evaluated over six consecutive growing seasons (2013–2018). Reducing the leaf-to-fruit ratio decreased berry sugar and anthocyanin concentration, slightly increased total organic acids, and modified the composition of free amino acids. Exogenous ABA significantly enhanced sugar and anthocyanin concentration and partially restored the balance of sugar and anthocyanins under a low leaf-to-fruit ratio, without altering free amino acid concentration or sugar to acids ratios. Conclusions Combining manipulation of the leaf-to-fruit ratio with application of exogenous ABA offers a potential method to reduce berry sugar concentration, while maintaining anthocyanin concentration. Significance of the Study This study paves the way for possible adaptation strategies for viticulture to global climate change.

Impact of phenolic compounds on free amino acid contents and electrophoretic patterns of the Nile Tilapia, Oreochromis niloticus

The present research was designed to determine the free amino acids (FAAs) composition and electrophoretic protein patterns by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in Oreochromis niloticus exposed to 1/10 LC50-96 hrs of phenol and nonylphenol ethoxylate 9 (NPEO 9) under laboratory condition for 4 weeks, in an attempt to develop sensitive bio-indicators for evaluation of pollution effects. Variations of FAAs were apparent in both treated groups. Significant increases were recorded in all individual amino acids including essential and non-essential ones, except for proline for both treated groups and leucine for phenol exposed fish group where they decreased significantly. The electrophoretic analysis of protein of the skeletal muscle homogenate using SDS-PAGE indicated that the control group yielded 10 fractions of molecular masses between 166 and 23 kDa. A total number of 9 bands were separated from fish of phenol group; they were varied from 168 to 23 kDa. However, 6 bands only were separated from fish of the NPEO 9 group; they were varied from 157 to 28 kDa. The muscle protein extract from fish of the phenol group showed five unique bands (168, 96, 68, 52, and 39 kDa). Moreover, fish that were exposed to NPEO 9 group showed three unique bands (157, 92, and 72 kDa). The highest similarity index S value observed between phenol and control groups was 0.37, followed by 0.33 between NPEO 9 group and the control one. This could be an indicator of changes in protein metabolism due to phenol and NPEO 9 pollution.

Effect of daily light integral treatments on free amino acids and sugars contributing flavor and acrylamide formation in potato tubers of Solanum tuberosum L.

To study the effect of photoperiodic conditions on the chemical composition of potato tubers, seven cultivars, grown under controlled conditions, were evaluated for the content of free amino acids (FAA) and sugars. The differences in these compounds may have an effect on the susceptibility of acrylamide formation during potato processing as well as on the flavor profile of potato products. Tubers were produced in growth chambers under two artificially induced photoperiods; 8 h light and 15 h light per day, resulting in conditions with two different daily light integral (DLI) levels. The photoperiodic treatments influenced the total FAA and free sugar contents and composition. Of the analyzed 19 FAAs, the concentrations of 14 FAAs were significantly lower in tubers exposed to the 15 h light period compared to 8 h light, whereas the glucose content was significantly higher. The total FAA concentrations were 15–46% lower and the glucose concentrations 6–64% higher in the seven cultivars exposed to the 15 h light conditions than in those grown in 8 h light.

Reduction of immunoreactivity and improvement of the nutritional qualities in cow milk products by enzymatic hydrolysis

Cow milk (CM) allergy has become a major health issue worldwide. However, studies of the immunoreactivity and nutritional qualities of CM following enzymatic hydrolysis are limited. We evaluated the immunoreactivity, protein pattern, free amino acid (FAA) composition, and nutritional qualities of CM after enzymatic hydrolysis. Decreased intensity of some major proteins, particularly, caseins (CNs), β-lactoglobulin (β-LG), and α-lactalbumin (ɑ-LA) were observed in enzymatically hydrolysed CM (HM). The IgE-binding and IgG-binding ability (CN, β-LG) in HM were significantly reduced (P < 0.05); the reduction rates of the IgE-binding and the IgG-binding ability (CN, β-LG) ranged from 44.24% to 50.07% and 57.89%–92.51%, respectively. CM showed a high protein content, whereas the protein contents of HM decreased markedly. Additionally, the contents of total FAAs in HM and the nutritional indices were significantly increased (P < 0.05), the FAAs scores of HM were higher than those of CM, and the nutritional score of CM obtained after Flavourzyme treatment was close to 1, which was remarkably higher than that of CM obtained after other enzyme treatments. These results can aid the development of CM products for infants and children with allergies and provide a theoretical foundation for future research in this field.