Umami Amino Acids Research Articles

Dynamic Changes in the Microbial Community and Metabolite Profile during the Pile Fermentation Process of Fuzhuan Brick Tea.

The pile fermentation process of Fuzhuan brick tea is unique in that it involves preheating without the use of starter cultures. The detailed metabolite changes and their drivers during this procedure are not known. Characterizing these unknown changes that occur in the metabolites and microbes during pile fermentation of Fuzhuan brick tea is important for industrial modernization of this traditional fermented food. Using microbial DNA amplicon sequencing, mass spectrometry-based untargeted metabolomics, and feature-based molecular networking, we herein reveal that significant changes in the microbial community occur before changes in the metabolite profile. These changes were characterized by a decrease in Klebsiella and Aspergillus, alongside an increase in Bacillus and Eurotium. The decrease in lysophosphatidylcholines, unsaturated fatty acids, and some astringent flavan-3-ols and bitter amino acids, as well as the increase in some less astringent flavan-3-ols and sweet or umami amino acids, contributed importantly to the overall changes observed in the metabolite profile. The majority of these changes was caused by bacterial metabolism and the corresponding heat generated by it.

TMT-labeled quantitative proteomic reveals the mechanism of proteolysis and taste improvement of dry-cured bacon with Staphylococcus co-inoculation

To understand the mechanism of co-inoculation of Staphylococcus xylosus and Staphylococcus vitulinus (SX & SV) on structural protein degradation and taste enhancement of dry-cured bacon, protease activities, protein degradation, surface morphology of proteins and taste parameters of dry-cured bacon with Staphylococcus inoculation were investigated. The dry-cured bacon with co-inoculation of Staphylococcus xylosus and Staphylococcus vitulinus showed the best taste attributes. High residual activities in cathepsin B + L (more than 1.6-fold) and alanyl aminopeptidase (more than 1.4-fold) accelerated structural protein degradation in SX & SV. 32 down-regulated proteins were identified in SX & SV by TMT-labeled quantitative proteomic compared with control group; myosin and actin showed the most intense response to the accumulation of sweet and umami amino acids, and atomic force microscopy confirmed structural proteins breakdown by morphological changes. The accumulation of glutamic acid, alanine and lysine was mainly responsible for taste improvement of dry-cured bacon with Staphylococcus co-inoculation.

Effect of Domestication on Nonvolatile Flavor Substances in Mud Crabs (Scylla paramamosain): A Way to Improve the Quality of Commercial Crabs.

In this study, the best domestication time for mud crabs (Scylla paramamosain) that were domesticated in the same region was explored. MC crabs (Mang Cai City, Vietnam), TS crabs (Taishan City, Guangdong Province, China), and NB crabs (Ningbo City, Zhejiang Province, China) were used as experiment groups, which were all domesticated in the Sanmen area for 28 days. Then, free amino acids and flavor nucleotides in muscles and hepatopancreas were determined. In MC and NB crabs, flavor amino acids in hepatopancreas and equivalent umami concentration (EUC) of flavor nucleotides in the hepatopancreas and muscles were lower than those of CK1 and CK3 crabs before domestication (0 day). There was no significant difference between MC and CK1 and between NB and CK3 crabs after 28 days of domestication. The content of umami amino acids, the total content of flavor nucleotides, and EUC in the hepatopancreas in TS crabs were lower than those in CK2 crabs and were still lower than those in CK2 crabs after 28 days of domestication. Therefore, it takes at least a month to domesticate mud crabs. The theoretical basis and technical reference for the directional cultivation of the flavor quality of mud crabs were provided in this study..

Effects of Dietary Curcumin on Growth and Flesh Quality in Juvenile Genetically Improved Farmed Tilapia (GIFT, Oreochromis niloticus)

This experiment was designed to investigate the effects of curcumin levels on growth, flesh quality, and oxidative resistance in juvenile genetically improved farmed tilapia (GIFT, Oreochromis niloticus). Fish (initial mean weight: 4.5 ± 0.3 g) were randomly fed five diets with curcumin supplementation levels of 0 (control), 150, 300, 600, and 1,200 mg/kg. After 60 days of feeding, the hepatosomatic index was significantly reduced in the curcumin supplemented groups. The 300 mg/kg group had the highest crude protein content of the whole fish. Compared to the control group, the crude fat content of whole fish in the 150 and 300 mg/kg groups was significantly reduced by 18.83%–19.74%, respectively. The highest values for muscular hardness, chewiness, myofibrillar density, and proportion of small-sized myofibers (<40 μm) were observed in the 300 mg/kg group. The levels of total nonessential amino acids and bitter amino acids in muscle were significantly lower in the 150 and 300 mg/kg groups than in the other groups. The 300 mg/kg group had higher levels of free sweet amino acids in the muscle than the other groups. Muscles from the 150, 300, and 600 mg/kg groups had significantly higher levels of umami amino acids than in the other groups. The levels of total free nonessential amino acids and total amino acids in serum were significantly higher in the 300 mg/kg group than in the control group. Serum aspartate transaminase activity was significantly lower in the curcumin supplementation groups than in the control group, and the serum alanine aminotransferase activity was significantly lower in the 150 mg/kg group than in the other groups. Serum superoxide dismutase activity was significantly higher in the curcumin supplementation groups than in the control group. Serum catalase activity was significantly higher in the 150 mg/kg group than in the other groups. The serum malondialdehyde level was lowest in the 150 mg/kg group. These results suggest that dietary curcumin supplementation in the diet at 150–300 mg/kg can effectively improve the nutritional value, muscle flavor, and antioxidant capacity of tilapia.

Different analysis of flavors among soft-boiled chicken: Based on GC-IMS and PLS-DA

To identify the influence of different chicken varieties on the flavor of soft-boiled chicken, four kinds of raw chicken materials including Tuergong, Huangyou, Mahuang and Feizifeng were used to produce soft-boiled chicken by traditional methods. Tuergong had the highest content of sweet and umami amino acids at 6.11%, 7.30% respectively. Huangyou was rich in moisture, but low in adenosine monophosphate of 30.10 mg/100 g. The chewiness and flavor nucleotide content of Mahuang were the minimum. Feizifeng had the slightest resilience and large number of flavor nucleotides. Combined with the results of electronic tongue, electronic nose, sensory evaluation and Gas Chromatography-Ion Mobility Spectrometry (GC-IMS), it was found that Tuergong had a relatively high score of taste and aroma with the largest value of electronic tongue of umami. However, the four varieties of soft-boiled chickens had no significant differences in the overall preference. Based on the partial least square discriminant analysis, 11 important volatile aroma compounds were identified. In addition, sweet and umami amino acids including Proline, Aspartic acid, Alanine and Glutamic acid were the most important substances affecting the flavor difference of soft-boiled chicken. In conclusion, white-feathered chicken Feizifeng can replace yellow-feathered chicken to produce soft-boiled chicken.

Overwintering temperature affects the nutrient composition and non-volatile flavor substances of female adult mud crab Scylla paramamosain in recirculating aquaculture systems (RASs)

This study investigated the effects of different overwintering temperatures (8, 12, 16, and 20 °C) on basic nutritional composition and non-volatile flavor substances, including free amino acids and free nucleotides of edible tissues (gonad, hepatopancreas, and muscle) of female mud crab Scylla paramamosain after eight-week of overwintering. The results showed that the overwintering process and temperature did not affect the basic nutritional composition of the gonad (P > 0.05). However, with the increase in temperature, the lipid content of hepatopancreas decreased and was accompanied by a rise in moisture content (P < 0.05). In muscle, moisture content increased significantly, and crude protein content decreased significantly after overwintering at 20 °C (P < 0.05). During the overwintering process and with the increase in temperature, free amino acids and free nucleotides decreased considerably (P < 0.05). In addition, each tissue had a high content of total sweet amino acids (SAA) under low overwintering temperatures. However, the contents of total umami amino acids (UAA) and equivalent umami concentration (EUC) increased significantly, accompanied by the decrease of total bitter amino acids (BAA) with the rising temperature (P < 0.05). To sum up, overwintering under high temperature was beneficial to improve the umami characteristic and reduce the bitter characteristic, but it would cause the crabs to lose and consume proteins and lipids. However, overwintering at low temperature had higher nutrients and sweet characteristic. Therefore, overwintering at 8–12 °C is more conducive to improving the nutritional quality and flavor of S. paramamosain.

Development of room-temperature fermented stinky sea bass and novel insights into its physicochemical and flavor formation and microbial diversity

The objective of this study was to created room-temperature fermented stinky sea bass (RFSB) and reported the first analysis of the dynamic changes in physicochemical properties, volatile compounds, and bacterial communities during the fermentation process. Results revealed that the texture of RFSB improved after fermentation, and proton freedom and mobility were reduced. The pH of sea bass increased, while the brightness and whiteness decreased with fermentation. The total concentrations of umami amino acids, pleasant-tasting amino acids, free amino acids, and guanosine-5′-monophosphate (GMP) significantly increased following fermentation, contributing to the freshness of RFSB. Twenty-eight flavor substances were detected during RFSB processing, including trimethylamine and indole, which may account for the stinky nature of RFSB. Additionally, we observed that Tetragenococcus was positively correlated with texture, pH, GMP, and free amino acids of RFSB. Achromobacter, Staphylococcus, Corynebacterium, Tetragenococcus, and Kurthia were significantly correlated with RFSB flavoring substances. This study can be used to guide future research on starter screening.

Widely targeted metabolomics investigation of the meat taste of Eriocheir sinensis under ammonia exposure

Ammonia-nitrogen may accumulate in the aquaculture water of Eriocheir sinensis. This study investigated the effects of ammonia exposure during 48 h (0, 10.47, and 41.87 mg/L) on the meat taste of E. sinensis. Sensory analysis showed that the low-concentration ammonia group had the highest umami and the lowest bitterness scores. Metabolomics combined with quantitative analysis showed that ammonia increased the 5′-inosine monophosphate content and the equivalent umami concentration and reduced the arginine content, thereby enhancing umami and reducing crab meat bitterness. Exposure to high concentrations of ammonia reduced umami amino acids (glutamic acid and aspartic acid) and increased bitter amino acid levels (leucine, isoleucine, and tryptophan), which hindered the taste development of crab meat. The increased levels of sweet amino acids (glutamine and serine) in the high-concentration ammonia group may be key ammonia detoxification products. This study revealed that phospholipids and small peptides may participate in improving crab meat flavor after ammonia exposure.

Effect of extrusion on the structural and flavor properties of oat flours

As widely consumed functional grain worldwide, oats have received increasing attention due to numerous health benefits. Compared to the traditional multistep baking methods (saturated steam and kiln drying), extrusion offered economic and practical advantages in time and energy savings, as well as consumer product quality. With the purpose of discovering potentially new products, this study investigated the impact of extrusion on starch structural and flavor profiles (volatile and non-volatile) in oat flour. The high temperature, high pressure, and high shear in the extrusion process changed the intimate texture of the oat flour into irregular, spongy texture, which forms V-type crystal structure. Extruded oat flour's gelatinization temperature was significantly lower than unextruded. Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry demonstrated significant increases in aldehydes and heterocycles after extrusion of oat flours. The odorants in raw oat flours, identified by gas chromatography-olfactometry and odor activity value changed from green to pleasant nutty, grass and bean fragrance in extruded flours. Furthermore, umami amino acid contents increased, while bitter amino acid contents decreased significantly. This study identified the structural and flavor differences in extruded oat flours and provided clues that could improve potential in the development of ready-to-eat cereals and snack foods.

Unraveling the core bacterial community responsible for quality and flavor improvement of the radish paocai during spontaneous fermentation

The effects of different varieties of radish on the quality and flavor of radish paocai are still elusive. Herein, this study aimed to compare the quality and flavor of radish paocai fermented by three kinds of radish, and further investigate the core bacterial community that mainly positively correlated with the quality and flavor improvement of paocai. As fermentation proceeded, pH and nitrite decreased, total acid and reducing sugar increased, and salinity showed a fluctuating decrease. Besides, LL had the highest content of reducing sugar and free amino acids, and CB had more organic acids and umami amino acids than other kinds of paocai. The bacterial community analysis confirmed that the variety of radish had little impact on bacterial succession, and Weissella, Lactobacillus, and Leuconostoc were found to be the core bacterial community that could promote the increase of organic acids, free amino acids, and volatile flavor compounds. In particular, Weissella was the biomarker on day 4 of fermentation, and Lactobacillus was the biomarker on day 7 in three kinds of radish paocai. Collectively, using different varieties of radish did not significantly induce change in the bacterial community of the radish paocai, although these radish paocai products presented different qualities and flavors.

Structure and flavor characteristics of Maillard reaction products derived from soybean meal hydrolysates-reducing sugars

In this study, the structure and flavor characteristics of soybean meal hydrolysates-reducing sugars Maillard reaction products (MRPs) were evaluated. Sugars added to the soybean meal enzymatic hydrolysates increased the Maillard reactivity in the following order: hexose < pentose. Results indicated that the intrinsic fluorescence intensity of MRPs increased, whereas the absorption peak intensity of the infrared spectrum changed significantly. Molecular weight analysis results showed that the MRPs were mainly distributed between 128-500 and 500–1000 Da. Furthermore, the bitter amino acid content (9.29 mg/g) and umami amino acid content (3.60 mg/g) were relatively high in ribose-MRPs. The umami, richness and bitterness values of pentose-MRPs were higher than those of hexose-MRPs. Moreover, the analysis of volatile substances showed that the ribose-MRPs presented a stronger caramel aroma, nutty flavor, and grilled meat flavor.

Effects of pre‐ultrasonication on small molecular metabolites and flavour compounds in chicken broth

SummaryThe chicken broth was pre‐treated with ultrasound at 0, 480, 600, 720 and 840 W for 30 min before stewing, and the changes of free fatty acids, small molecular compounds, volatile flavour compounds, umami polypeptides in the chicken broth were determined by GC–MS, UPLC‐Q‐Exactive‐MS, GC–IMS and LC–MS/MS, respectively. 600 W ultrasonic treatment group outperformed the other groups in terms of sensory evaluation (P &lt; 0.05). Palmitic acid and stearic acid were the chief free fatty acids in chicken broth. 530 and 236 small molecule metabolites were found. 36 volatile compounds were identified in chicken broth, mainly aldehydes. The proportion of sweet and umami amino acids in the chicken broth of the 600 W ultrasonic treatment group accounted for 63% of the total polypeptide sequence, indicating that pre‐ultrasonication can increase the content of sweet and umami polypeptides in chicken soup. The overall taste and flavour of Wuding chicken soup under pre‐ultrasonication with 600 W power were the best combined with sensory evaluation scores. These results can provide scientific and theoretical guidance for the further understanding of the effect of ultrasound assistance on the quality of chicken broth and the intensive processing of local chicken.

3D printable vegan plant-based meat analogue: Fortification with three different mushrooms, investigation of printability, and characterization

In this study, a meat analogue formulation prepared using different protein sources as a printable ink for 3D printers and fortified with three different mushroom cultivars (reishi, Ganoderma lucidum (GL); saffron milk-cap, Lactarius deliciosus (LD); and oyster, Pleurotus ostreatus (PO)). 3D printing performance of the prepared inks was evaluated by factorial design in terms of nozzle height, printing speed, and flow compensation. New methods of maximum layer height and reprintability of plant-based meat analogues were conducted for the first time. Inks were characterized by analyzing rheological properties, microstructure, color characteristics, texture profile, cooking loss, amino acid content, and sensory evaluation. Results showed that the nozzle height and printing speed were found to be most effective on accuracy of prints and smoothness of layers. All inks (C, GL, LD and PO) represented shear-thinning and gel-like viscoelastic behavior (G′ > G″) with predominant elasticity (tan δ < 1). Therefore they were suited for 3D printing and possessed supporting the following layers for additive manufacturing as well as meeting the criteria for a stable structure. Meat analogue was printed successfully without perceived defects in all formulations, except the GL was looking linty. LD and PO inks brought the advantage of recycling as a result of their re-printability whereas GL could not. Moreover, mushroom fortification reduced hardness, stiffness, springiness, and chewiness properties of the meat analogues whereas it increased the juiciness with reasonable overall acceptance. Mushroom fortification also enhanced the nutritional value and improved release of umami amino acids. The findings of the study demonstrated that mushrooms could be a functional and nutritious candidate for 3D printable plant-based meat analogues.

Growth, Biochemical Characteristics, Flesh Quality, and Gut Microbiota of the Pacific White Shrimp (Penaeus vannamei) Fed a Defatted Superworm (Zophobas atratus) Larvae Meal.

This study evaluated the effects of defatted superworm (Zophobas atratus) larvae meal (DBWLM) as an alternative protein ingredient for juvenile Pacific white shrimp (Penaeus vannamei). Six isonitrogenous and isolipidic experimental diets were characterized by replacing 0%, 15%, 30%, 45%, 60%, and 75% fish meal (DBWLM0, DBWLM15, DBWLM30, DBWLM45, DBWLM60, and DBWLM75, respectively) with DBWLM on a w/w basis and feeding them to juvenile shrimp (0.34 ± 0.04 g) for 56 days. The results showed that the replacement of up to 75% fish meal by DBWLM had no negative effect on the growth performance of P. vannamei. The survival of shrimp in the DBWLM30 group was the highest, and the weight gain, specific growth rate, feed conversion ratio, condition factor, and apparent digestibility coefficients of dry matter in the DBWLM15 group were the highest. The substitution of DBWLM for fish meal significantly increased the elasticity of flesh, improved the total content of umami amino acids in flesh (aspartic acid, glutamic acid, glycine, and alanine), promoted lipid metabolism in shrimp, and reduced serum lipid levels. With the increase in DBWLM level, serum acid phosphatase, alkaline phosphatase activity, and intestinal inflammatory gene expression (IGF-1 and IL-6) were inhibited, malondialdehyde content decreased, and total antioxidant capacity level and superoxide dismutase activity increased significantly. Histological sections of the hepatopancreas showed that when 60% or more fish meal was replaced, the hepatopancreas atrophied and had irregular lumen distortion, but the cell membrane was not damaged. Microbiome analysis showed that the abundance of Bacteroidetes and Firmicutes increased and the abundance of Proteobacteria decreased in the DBWLM replacement group, and it was rich in "metabolism"-related functional pathways. It is worth mentioning that the expression of amino-acid-related enzymes was upregulated in the DBWLM15 and DBWLM30 groups, and the DBWLM75 group inhibited the biosynthesis of steroids and hormones. To conclude, the replacement of 15%-45% fish meal with DBWLM can result in better growth and immune status, improved meat elasticity, and reduced inflammation in P. vannamei. However, it is recommended that the replacement level should not exceed 60%, otherwise it will cause atrophy of hepatopancreas cells.

Preparation of sunflower seed-derived umami protein hydrolysates and their synergistic effect with monosodium glutamate and disodium inosine-5'-monophosphate.

Sunflower seeds are rich in protein and can be an excellent raw material for the production of umami peptides. In this study, sunflower seed meal, which was defatted at a low temperature, was taken as the raw material, and proteins were separated, followed by hydrolyzation for 4h by flavourzyme® to obtain hydrolysates with strong umami intensity. These hydrolysates were deamidated using glutaminase to increase the umami intensity. The highest umami value of 11.48 was recorded for hydrolysates deamidated for 6h, and the umami intensity was determined. The umami hydrolysates mixed with 8.92mmol IMP + 8.02mmol MSG showed the highest umami value of 25.21. Different concentrations of ethanol were used for further separation of hydrolysates, and the highest umami value of 13.54 was observed for 20% ethanol fraction. The results of this study provide utilization method for sunflower seed meal protein and a theoretical basis for the preparation of umami peptides. PRACTICAL APPLICATION: A large number of sunflower seed meals after oil production are used as feed for livestock and poultry. Sunflower seed meal is rich in protein, and umami amino acid composition in sunflower seed meal is up to 25%-30%, which is potentially an excellent raw material for the production of umami peptides. The umami flavor and synergistic effect of obtained hydrolysates, with MSG and IMP, were analyzed in the present study. We intend to provide a novel way for utilization of protein from sunflower seed meal along with a theoretical basis for the preparation of umami peptides.

Insights into nutrition, flavor and edible quality changes of golden pomfret (Trachinotus ovatus) fillets prepared by different cooking methods.

In recent years, Asia has seen an increase in demand for golden pomfret (Trachinotus ovatus). Especially in instant (ready-to-eat) and prepared (ready-to-cock) food processing industry. Thermal processing is a vital part of food processing. However, no comprehensive analysis has been reported on its flavor, nutrition and edible quality changes during the key thermal processing. Accordingly, in this study, we evaluated the effects of different cooking methods (steaming, frying, microwaving and baking) on the color, texture, cooking loss, nutrition composition, volatile flavor substances and other indicators of golden pomfret filets. The results showed that the steamed samples (SS) had the lowest cooking loss and fat content, the highest moisture content, complete appearance and the lowest levels of hardness and chewiness. Fried samples (FS) had a notable difference in fatty acid composition. The content of unsaturated fatty acids (UFAs) increased significantly, while the relative content of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) decreased from 7.88 to 1.42%, lower than other groups. The essential amino acid index (EAAI) of microwaved samples (MS) was 94.89, which was higher than other groups. Baked samples (BS) had the highest relative content of umami amino acids (UAAs) and sweet amino acids (SAAs), which was 8.08 mg/100 mg and 5.19 mg/100 mg, respectively. Hexanal and nonanal were detected in control samples (CK), SS, FS, MS and BS. While pyrazine compounds were detected only in FS and BS. Steaming and microwaving treatment of golden pomfret resulted in better nutritional preservation, which was more conducive to human health. Frying and baking treatment of golden pomfret had better taste and flavor and higher sensory scores. The nutrition, flavor and edible quality of golden pomfret under different cooking methods were related and interactive. Cooking loss and fat content can be used as simple evaluation indicators to compare the overall quality of different cooking methods. This study provides a reference for the thermal processing technology and industrial production of golden pomfret.

Effect of fermentation with Tetragenococcus halophilus and Zygosaccharomyces rouxii on selected non-volatile taste compounds in soybean protein hydrolysates

This work was focused on investigating the effect of fermentation with Tetragenococcus halophilus and Zygosaccharomyces rouxii on the flavor characteristics of soy protein hydrolysates (SPH). The sensory attributes and non-volatile taste compounds of SPHs were analyzed using high performance liquid chromatography, electronic tongue and sensory evaluation. The results demonstrated that fermentation could effectively increase the contents of amino nitrogen, total acids, organic acids (especially lactic acid), umami amino acids (growth rate ranging from 10.9% to 30.6%) and sweet amino acids (increased by 7.8%–62.0%) compared with control groups, contributing to improve the acidity, as well as umaminess and sweetness taste of samples. Principal component analyses and partial least square discriminant analyses confirmed the substantial impacts on the non-volatile taste characteristics of SPHs by lactic acid bacteria (LAB) and yeast fermentation, especially for the flavor profile of the sample with Aspergillus oryzae hydrolysis and sequential addition of LAB and yeast (SFH-2), and the sample with commercial protease hydrolysis and simultaneous addition of LAB and yeast (SH-1). These findings provided a theoretical basis for enhancing the flavor intensity of soybean protein hydrolysates.

Application of electronic tongue in umami detection and soy sauce refining process.

The article systematically investigated the response behaviors of lipid-film equipped umami taste sensor to various umami compounds, including typical umami substances (umami amino acids, GMP, IMP, disodium succinate) and novel umami chemicals (umami peptide and Amadori rearrangement product of umami amino acid). The umami taste sensor has great specificity to all umami substances. Relationships between output values and concentrations of umami substances in certain ranges were consistent with Weber-Fechner law. The umami synergistic effect detected by the sensor was in great agreement with human sensory results as well, fitting logarithm model. Moreover, the taste profile mixing model of raw soy sauce was established using five different taste sensors and principal component analysis, realizing the simplification of soy sauce blending and acceleration of the soy sauce refining process. Thus, flexible design of the experimental procedure and multi-analysis of the sensor data is essential.

Effects of different drying treatments on the microstructure, free amino acids, volatile compounds and antioxidant activity of Flammulina velutipes root.

Drying treatments are an effective method of preserving the beneficial properties of postharvest mushrooms. The effects of natural-air drying (ND), hot-air drying (HD), vacuum-freeze drying (FD), heat pump drying (HPD) and microwave-vacuum drying (MVD) on the microstructure, flavor- and health-related compounds of F. velutipes root were investigated. The results showed that FD had the least impact on the microstructure of F. velutipes root and its original porous fiber structure appeared complete. It also possessed the highest content of volatile compounds. MVD gave the highest contents of umami amino acids, total phenolics and total flavonoids, and its extract exhibited high antioxidant activity. In addition, different drying treatments had significant effect on the chemical components of F. velutipes root, with FD and MVD may be the potent drying strategies for preservation of flavor and nutraceuticals respectively. Therefore, our results provided essential data support for F. velutipes root processing and functional product development.

Feasibility of using free bioactive amines and amino acids for quality assessment and discrimination of animal meals

The meat industry generates loads of residues, and its efficient utilization as animal meals is important from the environmental, economic, nutritional and safety points of view. The objective of this study was to investigate free amino acids and amines by ultra-performance liquid chromatography – UPLC™ in different types of animal meals and the feasibility of using them as quality and differentiation indices. Overall, 48 samples were analyzed; four types of meal [Feather meals (FM), meat & bone meals - bovine (MBM), pork/swine meals (SM), and Poultry meal (PM)] from 4 rendering plants; 3 different lots each). FM had higher protein and lower fat, whereas MBM) had higher ash, Ca and P (P < 0.05). Mercury was found in every sample (≤0.2 mg/kg). Total free amino acids were higher in MBM, and FM compared to the others (P < 0.05). FM had higher methionine, aspartic acid, and asparagine; SM had higher histidine (P < 0.05), which was not detected in MBM and FM. Phenylalanine was only found in MBM. Umami amino acids were prevalent in MBM; sweet amino acids in SM and FM; and bitter amino acids in SM and FM, thereby affecting palatability. PM had the widest diversity of amines (8), whereas MBM had the lowest (4). Higher amines levels were found in PM, and SM had the least (P < 0.05). Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) differentiated FM from MBM and from SM+PM, mainly by free amino acids and amines. The rendering plant D did not fit into any of the clusters, suggesting the poorest quality. Free amino acids and amines may be used as authenticity and quality indices for animal meals and rendering plants.