Total Amino Acid Content Research Articles

Changes and dynamics of the main quality components in tea leaves of 4 tea cultivars during the shading process

The purpose of this study was to analyze the relationship between different shading conditions, picking time for main quality components of tea. The main quality components of 4 tea cultivars [Camellia sinensis (L.) O. Kuntze], including the separated tea shoot tissues (leaves, buds, stems), under 4 shading rates during the traditional 20-day shading period were examined. Results showed the Chlorophyll contents after 12 days of shading treatment were significantly higher than control, but after that it ceased increasing significantly Initially, the theanine, total free amino acid, caffeine, and tea polyphenol contents showed decreased trend but then leveled off after 12 days. The increase of free amino acids, caffeine, chlorophyll and the decrease of tea polyphenols induced by shading were mainly determined by shading level and tenderness. Meanwhile, shading changed the proportion of main quality components in tea leaves and stems, long-term shading does not promote high quality matcha. All of the results indicated the quality of matcha with grade 1 could be produced by shading rate of 80 % and shading for 12 days. Appropriate shading time and shading rate are beneficial to improve the quality of Matcha.

Peatland carbon chemistry, amino acids and protein preservation in biogeochemically distinct ecohydrologic layers

AbstractPeatlands play a significant role in global carbon and nitrogen cycles due to their carbon storage capabilities. However, there are key knowledge gaps in our understanding of how peatland hydrology influences the biogeochemical properties that drive peatland functioning and health. This study examines peatland hydrology and biogeochemical dynamics by exploring the variations in carbon chemistry, total amino acid (‘protein’) content and amino acid composition in the ecohydrologic layers: acrotelm, mesotelm and catotelm. The dynamic movement of the water table recorded half‐hourly over 4 years was used to assist in identifying the boundaries between these layers. Peat amino acids were measured using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). Carbon chemistry was analysed by solid state Cross Polarization Magic Angle Spinning (CPMAS) 13C Nuclear Magnetic Resonance (NMR) spectroscopy, with the alkyl:O‐alkyl ratio used to quantify the extent of decomposition. Our result revealed a strong positive correlation between the extent of decomposition and total protein content, indicating selective preservation of proteinaceous materials during peat decomposition. Each ecohydrologic layer displayed a distinct amino acid composition and carbon functional group composition. The acrotelm was relatively enriched in seven amino acids and two carbon functional groups. The mesotelm was relatively enriched in four amino acids, while the catotelm was relatively enriched in three amino acids and four carbon functional groups. The variations in amino acid composition reflect differences in microbial function and efficiency, while variations in carbon functional groups provide insights into long‐term carbon sequestration in peatland. Collectively, these results provide more insights into nutrient cycling and changes in organic matter composition during peat decomposition. These findings demonstrate that peatland biogeochemistry is closely linked to ecohydrology and suggest that changes to water table dynamics could affect the ability of peatlands to sequester and store carbon in the future.

Effect of ultrasound‐assisted osmotic dehydration on the drying characteristics and quality properties of goji

AbstractThe waxy layer on the surface of the goji fruit increases the dehydration time. In this study, the novel use of ultrasound pretreatment (10, 20, and 30 min) assisted with osmotic dehydration was utilized to improve drying efficiency and product quality of goji. The results showed that goji treated with ultrasound‐assisted osmotic dehydration lost more water and gained more solids during osmotic dehydration than goji treated with osmotic dehydration only. Furthermore, the ultrasound‐assisted osmotic dehydration pretreatment method shortened the drying time for freezing drying goji and lowered the water activity of the dried goji. This may be due to the destruction of the wax layer on the surface of the goji by ultrasound. The rehydration rate of the goji treated with ultrasound for 20 min was significantly higher than that of the samples dried by osmosis dehydration only. The application of ultrasound‐assisted osmotic dehydration resulted in the best color and the highest glutathione and total free amino acid content of goji, especially the taurine. Besides the above, the antioxidant capacity of ultrasound‐assisted osmotic dehydration‐treated goji was enhanced, with the highest 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging capacity and ferric reducing antioxidant power (FRAP) values for the samples in the 20‐min ultrasound‐assisted group. The results demonstrate that ultrasound‐assisted osmotic dehydration not only reduces the drying time of goji but also enhances its product quality.Practical applicationsThis study explored the effects of different ultrasound‐assisted osmotic dehydration methods on the drying efficiency and quality of freeze‐dried goji. The findings provide a scientific basis for improving goji drying engineering and offer a potential strategy for enhancing goji quality.

Characterization of Yeast Protein Hydrolysate for Potential Application as a Feed Additive.

Yeast protein can be a nutritionally suitable auxiliary protein source in livestock food. The breakdown of proteins and thereby generating high-quality peptide, typically provides nutritional benefits. Enzyme hydrolysis has been effectively uesed to generate peptides; however, studies on the potential applications of different types of enzymes to produce yeast protein hydrolysates remain limited. This study investigated the effects of endo- (alcalase and neutrase) and exotype (flavourzyme and prozyme 2000P) enzyme treatments on yeast protein. Endotype enzymes facilitate a higher hydrolysis efficiency in yeast proteins than exotype enzymes. The highest degree of hydrolysis was observed for the protein treated with neutrase, which was followed by alcalase, prozyme 2000P, and flavourzyme. Furthermore, endotype enzyme treated proteins exhibited higher solubility than their exotype counterparts. Notably, the more uniform particle size distribution was observed in endotype treated yeast protein. Moreover, compared with the original yeast protein, the enzymatic protein hydrolysates possessed a higher content of β-sheets structures, indicating their higher structural stability. Regardless of enzyme type, enzyme treated protein possessed a higher total free amino acid content including essential amino acids. Therefore, this study provides significant insights into the production of protein hydrolysates as an alternative protein material.

Determining the influence of hemp seed protein on the quality indicators of cheese product and the content of nutrients in it

The growing tendency to produce cheese from animal and plant ingredients has led to the diversification of cheese-making technologies and the search for new cheese suitable raw materials. The research object is the technology of cheeses made from combined raw materials: cow's milk and hemp seed proteins. Subjects of research: organoleptic and physical-chemical indicators of cheese product samples; amino acid composition of cheese product samples. The inclusion of vegetable raw materials in the cheese technology affects the technical properties of milk-plant mixtures, in particular, their syrupy properties, and the quality of the finished cheese product. Samples of cheeses were produced according to the traditional technology of Cachotta type cheese. The conducted research established that the proteins of hemp seeds affect the sensory characteristics of cheese. Increasing the content of hemp protein in recipes leads to the appearance of a brown-green color of the cheese product. The taste and smell acquire a characteristic shade of hemp. When vegetable proteins are used in the recipe of cheese, the yield of the finished product increases by 0.3...23.5 %. In experimental samples, the content of fat (by 0.3...2.2 %) and protein (by 1.75...10.4 %) increases. Hemp seed protein balances the amino acid profile in finished cheese. The total content of amino acids in cheese samples was as follows: H10 – 8.25, H15 – 8.35, H20 – 8.44, and H25 – 8.53 mg/g of protein, which is relatively higher than in the control sample H0 – 8.08 mg/g of protein. Taking into account the results of the sensory analysis of the expert commission and the balanced biological profile, the recommended concentration of hemp seed protein in the milk-vegetable mixture is 20 %, which guarantees the acceptable quality of the product. The obtained results are of practical importance, since it can be taken into account that the combination of raw materials of plant and animal origin expands the assortment, increases the raw material base and the output of cheese, and therefore, the profitability of production

Bacillus velezensis strain NA16 shows high poultry feather-degrading efficiency, protease and amino acid production

Isolated Bacillus velezensis strain NA16, which produces proteases, amino acids and the transcription levels of different keratinolytic enzymes and disulfide reductase genes in whole gene sequencing, was evaluated during feather degradation. The result shows under optimum fermentation conditions, chicken feather fermentation showed total amino acid concentration of 7599 mg/L, degradation efficiency of 99.3% at 72 h, and protease activity of 1058 U/mL and keratinase activity of 288 U/mL at 48 h. Goose feather fermentation showed total amino acid concentration of 4918 mg/L (96 h), and degradation efficiency was 98.9% at 120 h. Chicken feather fermentation broth at 72 h showed high levels of 17 amino acids, particularly phenylalanine (1050 ± 1.90 mg/L), valine (960 ± 1.04 mg/L), and glutamic (950 ± 3.00 mg/L). Scanning electron microscopy and Fourier transform infrared analysis revealed the essential role of peptide bond cleavage in structural changes and degradation of feathers. Protein purification and zymographic analyses revealed a key role in feather degradation of the 39-kDa protein encoded by gene1031, identified as an S8 family serine peptidase. Whole genome sequencing of NA16 revealed 26 metalloproteinase genes and 22 serine protease genes. Among the proteins, S8 family serine peptidase (gene1031, gene1428) and S9 family peptidase (gene3132) were shown by transcription analysis to play major roles in chicken feather degradation. These findings revealed the transcription levels of different families of keratinolytic enzymes in the degradation of feather keratin by microorganisms, and suggested potential applications of NA16 in feather waste management and amino acid production.

Non-proteinogenic amino acids mitigate oxidative stress and enhance the resistance of common bean plants against Sclerotinia sclerotiorum.

White mold, caused by the necrotrophic fungus Sclerotinia sclerotiorum, is a challenging disease to common bean cultivation worldwide. In the current study, two non-proteinogenic amino acids (NPAAs), γ-aminobutyric acid (GABA) and ß-alanine, were suggested as innovative environmentally acceptable alternatives for more sustainable management of white mold disease. In vitro, GABA and ß-alanine individually demonstrated potent dose-dependent fungistatic activity and effectively impeded the radial growth and development of S. sclerotiorum mycelium. Moreover, the application of GABA or ß-alanine as a seed treatment followed by three root drench applications efficiently decreased the disease severity, stimulated plant growth, and boosted the content of photosynthetic pigments of treated S. sclerotiorum-infected plants. Furthermore, although higher levels of hydrogen peroxide (H2O2), superoxide anion (O2 •-), and malondialdehyde (MDA) indicated that S. sclerotiorum infection had markedly triggered oxidative stress in infected bean plants, the exogenous application of both NPAAs significantly reduced the levels of the three studied oxidative stress indicators. Additionally, the application of GABA and ß-alanine increased the levels of both non-enzymatic (total soluble phenolics and flavonoids), as well as enzymatic (catalase [CAT], peroxidases [POX], and polyphenol oxidase [PPO]) antioxidants in the leaves of S. sclerotiorum-infected plants and improved their scavenging activity and antioxidant efficiency. Applications of GABA and ß-alanine also raised the proline and total amino acid content of infected bean plants. Lastly, the application of both NPAAs upregulated the three antioxidant-related genes PvCAT1, PvCuZnSOD1, and PvGR. Collectively, the fungistatic activity of NPAAs, coupled with their ability to alleviate oxidative stress, enhance antioxidant defenses, and stimulate plant growth, establishes them as promising eco-friendly alternatives for white mold disease management for sustainable bean production.

Feeding ration of yaks of the Kyrgyz population and its influence on the biochemical composition of milk

Yaks are the large herbivorous ruminants that live in high mountain pastures at altitudes from 2,000 to 4,000 m above sea level. This environment is quite harsh, and yaks calmly tolerate extreme cold — down to minus 40 ºС. The main food of yaks are herbaceous plants, the vegetation season of which in a cold mountain climate is short, about 3–4 months, and therefore they feed mostly on wilted pasture, which is, in principle, sufficient for these animals. At the end of winter, when the amount of pasture feed decreases, the animals become malnourished and lose weight. Therefore, yak farmers often face the need to feed their animals in winter. A complete ration of an animal, along with other factors, has a significant impact on the composition of milk and its productive ability. The aim of the work is to study the chemical composition, in particular the protein fraction, of the milk of yaks living in the mountainous regions of Kyrgyzstan in comparison with the milk of yaks from different regions of the world. The object of the study was milk of yaks inhabiting the highland regions of Naryn province of Kyrgyzstan. Samples were collected and tested according to standard methods. Studies have shown that the milk of yaks from the Kyrgyz population contains more protein (5.66%) than milk from yaks in the mountains of China, Russia and Mongolia (4.95, 4.55 and 5.3%, respectively). Milk we studied is high in amino acids such as methionine, lysine, proline, phenylalanine, and alanine. Seasonal (spring, summer) changes in the protein composition (whey proteins, casein proteins), amino acid profile, total nitrogen, non-protein nitrogen of yak milk were also studied. The total content of amino acids in the milk of Kyrgyz female yaks is noticeably higher in spring (6189.96 mg/100 g) than in summer (5101.47 mg/100 g). The research results presented in this article showed that the milking season and the associated feeding ration of yaks affects the composition of milk, which is associated with the nutritional value of grass feed and its nutrient content. Spring milk contains more proteins and amino acids than summer milk, which is due to the high protein content of plants in the spring period before the flowering phase. Milk of Kyrgyz yak with proven high nutritional and biological value is an alternative to cow milk.

Characterization of kombucha prepared from black tea and coffee leaves: A comparative analysis of physiochemical properties, bioactive components, and bioactivities.

The utilization of coffee leaves in kombucha production has intrigued researchers; however, the lack of understanding regarding the characteristics of coffee leaf kombucha (CK) and its differentiation from black tea kombucha (BK) has impeded its application in the beverage industry. Therefore, this study aimed to characterize and compare the physiochemical properties, phytochemical compositions, antioxidant activity, and α-glucosidase inhibitory ability of kombucha prepared from the leaves of Coffea arabica (CK) and black tea (Camellia sinensis, BK) and their extracts (CT and BT). After fermentation, pH and the contents of total sugars, reducing sugars, and free amino acids of BK and CK were decreased, whereas the levels of total acids and organic acids, such as gluconic, lactic, and acetic acid were increased. Notably, the concentration of vitamin C in CK was 48.9% higher than that in BK. HPLC analysis exhibited that 5-caffeoylquinic acid in CT was significantly decreased by 48.0% in CK, whereas the levels of 3-caffeoylquinic acid and 4-caffeoylquinic acid were significantly increased after fermentation. The content of caffeine was significantly (p<0.05) reduced by 9.5% and 22.0% in BK and CK, respectively, whereas thetheobromine level was significantly increased in CK. Notably, CK has superior total phenolic and flavonoid contents and antioxidant activity than BK, whereas BK possesses higher α-glucosidase inhibitory capacity. Electronic nose analysis demonstrated that sulfur-containing organics were the main volatiles in both kombuchas, and fermentation significantly increased their levels. Our study indicates that coffee leaves are a promising resource for preparing kombucha. PRACTICAL APPLICATION: This article investigates the differences in physicochemical properties, bioactive constituents, antioxidant activity, and α-glucosidase inhibitory activity of kombucha preparation from black tea and coffee leaves. We have found that after fermentation BK had brighter soup color and higher α-glucosidase inhibitory capacity, whereas CK had higher levels of total phenols, flavonoids, vitamin C, and antioxidants and lower contents of sugars. This study provides valuable information for the preparation of CK with high-quality attributes and antioxidant activity.

Eco-physiological adaptation strategies of dominant tree species in response to canopy and understory simulated nitrogen deposition in a warm temperate forest

Nitrogen (N) is an indispensable element for plant growth and survival. The increased global N deposition due to human activities has aroused attention to forest ecosystems, but most studies have not considered the process of N interception, assimilation, and leaching in forest canopy. To investigate the responses and adaptive strategies of dominant tree species in a warm temperate forest to atmospheric N deposition, this study implemented five treatments: control treatment, canopy simulated low N deposition, canopy simulated high N deposition, understory simulated low N deposition, and understory simulated high N deposition. The morphological and physiological traits and nutrient uptake strategies of three dominant tree species (Liquidambar formosana, Quercus acutissima, and Quercus variabilis) in warm temperate deciduous broad-leaved forest were studied under different forms and levels of stimulated N deposition. The results showed that the specific leaf area (SLA) of the three dominant tree species decreased under high N application. To optimize resource absorption and improve nutrient transport rates, the specific root length (SRL) and specific root area (SRA) of the three tree species tended to decrease, while the average root diameter (ARD) increased. Under canopy N deposition (CAN), the contents of carbon (C), N, total chlorophyll (Tchl), and total amino acids in Q. variabilis leaves were lower than those under understory N deposition (UAN) treatment. Furthermore, principal component analysis (PCA) revealed the differences between different genera (L. formosana and Q. variabilis, L. formosana and Q. acutissima) under various N treatments, and there was no significant difference between the same genus (Q. variabilis and Q. acutissima). The results indicated that the eco-physiological characteristics of different tree species under N deposition treatment were species-specific, and traditional UAN perhaps exaggerated the effect of atmospheric N deposition on tree growth characteristics. Our study considers the retention and redistribution of forest canopy, which is more in accordance with the natural N deposition, and helps us to understand the eco-physiological responses of dominant tree species in forest ecosystem to atmospheric N deposition.

Physicochemical, Quality and Flavor Characteristics of Starch Noodles with Auricularia cornea var. Li. Powder.

Auricularia cornea var. Li., as an edible mushroom rich in various nutrients, could be widely used in noodle food. This study aimed to investigate the effect of Auricularia cornea var. Li. (AU) powder on the gel properties, structure and quality of starch noodles. Taking the sample without adding AU powder as a control, the addition of AU powder enhanced the peak viscosity, trough viscosity, final viscosity, breakdown, setback, peak time, gelatinization temperature, G' (storage modulus) and G'' (loss modulus). Meanwhile, the incorporation of AU powder significantly enhanced the stability of the starch gel structure and contributed to a more ordered microstructure also promoting the short-term aging of starch paste. In vitro digestion results displayed lower rapid digestibility (21.68%) but higher resistant starch content (26.58%) with the addition of AU powder and increased breaking rate, cooking loss, swelling index and a* and b* values. However, it decreased dry matter content and L*, particularly the reducing sugar content significantly increased to 4.01% (p < 0.05), and the total amino acid content rose to 349.91 mg/g. The GC-IMS library identified 51 VOCs, and the OPLS-DA model classified 18 VOCs (VIP > 1). Overall, the findings indicate that starch noodles with the addition of AU powder may provide greater nutritional quality, gel stability and starch antidigestibility.

Scrutinizing the Antimicrobial and Antioxidant Potency of European Cranberry Bush (Viburnum opulus L.) Extracts

In the process of considering the documented health benefits of Viburnum opulus L. (V. opulus), including its anti-inflammatory and antioxidant activities, the present study was designed to qualitatively and quantitatively evaluate the biochemical profile and antimicrobial potency of four commercially available V. opulus extracts. These extracts were obtained from its flowers, bark, berries, and a mixture thereof by cold ultrasound-assisted extraction. An examination of the V. opulus extracts indicated a relative abundance of group compounds, such as phenolics, flavonoids, tannins, and anthocyanins, which are responsible for antioxidant activity (AOA). The widest range in all of the four group compounds was detected in the V. opulus extract sourced from berries, whereas the narrowest range was found in those obtained from flowers. The HPLC-ESI-TQ-MS/MS technique displayed relative fluctuations in the concentrations of individual amino acids (AAs) over the four V. opulus extracts. The prevalence of proline was marked in the flower-derived extract, which made up 63.3% of the total AAs, while aspartic and glutamic acids dominated in the berry-derived extract by contributing up to 29.2 and 24.4% to the total AA content, respectively. Profiling of the individual phenolic compounds disclosed the superiority of chlorogenic acid (up to 90.3%) in the berry and mixed extracts, as well as catechin (up to 57.7%) and neochlorogenic acid (11.1%) in the bark extract, which conveyed a remarkable contribution toward antimicrobial activity. The lowest content of individual phenolics was found in the flower extract. Owing to its substantially denser bioactive composition, the V. opulus berries and bark extracts exhibited markedly better AOA, which was pinpointed by three independent methods, i.e., DPPH•, FRAP, and ABTS•+, than those obtained from flowers or a mixture of V. opulus morphological parts. As part of the antimicrobial activity testing, the V. opulus extracts exhibited outstanding inhibitory activity and a homeopathic mode of action. The V. opulus extracts obtained from a mixture, bark, and berries were more active against 8 out of 19 selected test microorganisms at minimum inhibitory concentration (MIC) values that ranged from 0.24 to 0.49 µL mL−1. Overall, the extracts of V. opulus were found to be effective against Gram-positive and Gram-negative bacteria. However, their conceivable exploitation as functional or pharmaceutical ingredients must be further clarified within in vivo models.

HYDROLYSATE CHARACTERISTICS OF BERUNOK SEA CUCUMBER (Paracaudina australis) AND TOTAL AMINO ACID USING PEPSIN ENZYMES

Berunok sea cucumber has a nutritional content that can be utilized as a functional food ingredient. This study determined the characteristics of berunok sea cucumber hydrolysate (Paracaudina australis) and the type and level of total amino acids. This research was conducted using experimental methods, with a Non-Factor Complete Randomized Design consisting of 3 levels of enzyme concentration treatment (1%, 2%, and 3%) with three replicates. In this study, the parameters tested were the proximate content of flour and hydrolysate of berunok and the type and content of total amino acids. The results showed that the chemical composition of berunok flour was water 11,40% (dw), ash 10,82% (dw), protein 68,21% (dw), fat 6,53% (dw), and carbohydrate by the difference of 14,43% (dw). The best treatment for preparing berunok protein hydrolysate using pepsin enzyme is 2% pepsin enzyme concentration. The proximate of berunok protein hydrolysate is water 6.87% (dw), ash 8.45% (dw), protein 80,59% (dw), and fat 2,86% (dw). The results of the identification of types and levels of total amino acids found 17 kinds of amino acids with a total of 16.524% in hydrolysate berunok.

Influence of methyl jasmonate and methyl jasmonate plus urea foliar applications on amino acids composition throughout ‘Tempranillo’ grape ripening over two seasons

This work studies the impact of foliar application of methyl jasmonate (MeJA) and methyl jasmonate plus urea (MeJA + Ur) on the evolution of amino acid content in ‘Tempranillo’ grapes during ripening, across two vintages. To achieve this goal, sample grapes were harvested at five different timing. Fol1: 1 day before first foliar application; Fol2: 1 day before second foliar application; Preharvest: 15 days after second foliar application; Harvest: the day of harvest; and Postharvest: 15 days after harvest. The effect of foliar treatments was season dependent, being effective to improve the amino acids content of grapes only in the first vintage. Among the treatments studied, foliar application of MeJA-Ur showed better results. The evolution of amino acids during ripening also was different among seasons. Overall, in the 2019, amino acids reached their highest content at Preharvest or Harvest samples, whereas in the 2020 season, these highest concentrations were reached at Postharvest. Asparagine might serve as a suitable amino acid for controlling grape ripening, as its content decreased from Fol1 to Postharvest in the two vintages. Moreover, differences on the total amino acids content at Harvest date between vintages were observed, probably due to different climatological conditions. Therefore, this study pioneers the examination of the impact of foliar applications of MeJA and MeJA + Ur on the amino acids evolution in ‘Tempranillo’ grapes during ripening. The need for further research is clear to comprehend the complex interaction between foliar treatments and grape amino acids dynamics for optimizing nitrogen quality of grapes.

Inhibition of postharvest browning of white Hypsizygus marmoreus by LVEF-Vac: Evidence from phenolic metabolism and enzyme expression

A study was conducted to examine the effects of postharvest anti-browning of white Hypsizygus marmoreus and the enzymes related to it, utilizing the Low Voltage Electrostatic Field-Vacuum (LVEF-Vac, 150 V, 100 Hz, 26–36 kPa) treatment technology. The findings indicated that the application of LVEF-Vac treatment significantly extended the storage time of white Hypsizygus marmoreus to 14 d as compared to the control groups. Additionally, it successfully prevented the rise in color difference and browning degree, reduce them by 21.23 % and 36.62 %, respectively, while also inhibiting water loss and migration. Furthermore, it can impede the increase in total amino acid, tyrosine, and lysine content while maintaining a high proline and total phenols content of white Hypsizygus marmoreus during storage. At 9 d of storage, LVEF-vac treated laccase activity was reduced by 32.56 %, tyrosinase activity was reduced by 40.35 %, and gene expression of laccase and tyrosinase was reduced by 93.67 % and 48.77 %, respectively. Therefore, the discoloration of white Hypsizygus marmoreus during storage is slowed down, which improves its quality over time.

Feasibility of Enzymatic Protein Extraction from a Dehydrated Fish Biomass Obtained from Unsorted Canned Yellowfin Tuna Side Streams: Part II.

The enzymatic extraction of proteins from fish biomasses is being widely investigated. However, little or almost no research has paid attention to the exploitation of unsorted fishery biomasses. This work is part of a larger study, Part I of which has already been published, and focuses on an extensive characterization of two collagenous samples, namely gelatin (G) and hydrolyzed gelatin peptides (HGPs), extracted from a dehydrated fish biomass coming from unsorted canned yellowfin tuna side streams. The results indicate crude protein fractions of 90-93%, pH values between 3 and 5, white-yellow colors, collagen-like FTIR spectra, and 17% in terms of total amino acid content. Viscosity and the study of dynamic viscous-elastic behavior were analyzed. Thermo-gravimetric analysis was performed to assess the residual ashes. Both samples were investigated to determine their molecular weight distribution via size-exclusion chromatography, with a higher total average molecular weight for G compared to HGPs, with values of 17,265.5 Da and 2637.5 Da, respectively. G demonstrated technological properties similar to analogous marine gelatins. HGPs demonstrated antioxidant activity as per FRAP assay. All the results open up new perspectives for the potential use of these substances in biodegradable packaging, dietary supplements, and skin care cosmetics.

The pH acidity and nitrate accumulation by plasma discharge enhanced the growth and phytochemicals of soybean sprouts grown in reused water

This study investigated the effect of plasma treatment on reused water and evaluated the interactions of the plasma-treated water (PTW) with plants or microbes to determine the optimal PTW for reuse. The repeated treatment gradually accumulated nitrate (NO3−) in the PTW and lowered its pH; afterward, it led to the sprouted soybeans accumulating other inorganic ions in the PTW. The biomass of soybean sprouts was enhanced by the accumulated NO3− but decreased due to the pH effect. Meanwhile, the acidic pH reduced the microbial counts, but they increased after sprinkling the PTW over the sprouts. The optimal PTW in our study, which had a gradual increase of NO3− (≤321.8 mg·L−1) with an acceptable pH (≥pH 3), significantly enhanced the biomass by 4.2% compared to the untreated control. Additionally, it increased the total content of amino acids and isoflavones by 9% and 18% in the growing part, respectively.

Evaluation of nutritional value of Bambusae Concretio Silicea based on content of 15 amino acids

The content of 15 total amino acids(TAAs) in Bambusae Concretio Silicea was determined by HPLC with phenyl-isothiocyanate(PITC) for pre-column derivatization. The results showed that the content of TAA was 0.61-12.25 mg·g~(-1), and aspartic acid(Asp), glutamic acid(Glu), proline(Pro), glycine(Gly), and valine(Val) were the top five amino acids in terms of the average content. The content of essential amino acids(EAAs), conditionally essential amino acids(CEAAs), non-essential amino acids(NEAAs), and medicinal amino acids(MAAs) was 0.24-4.75, 0.30-4.73, 0.40-7.50, and 0.36-6.51 mg·g~(-1), respectively. Among the delicious amino acids, sweet amino acids(SAA), bitter amino acids(BAA), fresh-taste amino acids(FAAs), and odourless amino acids(OAAs) had the content of 0.22-4.70, 0.19-4.03, 0.13-2.26, and 0.06-1.26 mg·g~(-1), respectively. The 21 batches of Bambusae Concretio Silicea samples presented the same composition but significant differences in the content of amino acids. Among the three producing areas, Guangdong was the area where the samples had the highest content of TAAs, EAAs, CEAAs, NEAAs, MAAs, and delicious amino acids. Furthermore, the ratio of amino acid(RAA), ratio coefficient of amino acid(RCAA), and score of ratio coefficient of amino acid(SRCAA) were calculated to evaluate the nutritional value of Bambusae Concretio Silicea. The results showed that the Bambusae Concretio Silicea samples from Guangdong had better nutritional value. The nutritional value evaluation based on the content of 15 amino acids was proposed to provide data support for the quality grading of Bambusae Concretio Silicea and lay a foundation for the development and utilization of the medicinal material resources.

Nutrient composition and taste properties of Sargassum fusiforme from the Wando region

This study examined the nutrient composition and taste properties of Sargassum fusiforme (SF) from two locations in the Wando region (Wando-eup: WD-A, Sinji-myeon: WD-B) and control region in Korea. The protein content of the SF in Wando regions was higher than that of the control, while the carbohydrate content was lower. The WD-A region had the lowest calorie content and the highest ash level when compared to the other regions. The potassium, iron, and zinc contents of the in WD-A were significantly higher than the other groups, but the sodium, phosphorus, and magnesium contents were lower. Free and constitutive amino acids, as well as the total and essential amino acid content, were higher in Wando regions than in the control. When analyzing using an electronic tongue, the SF from the WD-A region had the highest umami and sourness and the lowest bitterness and sweetness. Therefore, the results of this study can serve as fundamental data for seaweed research in the Wando region.

Effect of limited hydrolysis with endopeptidase on bitterness properties of wheat gluten hydrolysates

The application of limited hydrolysis on wheat gluten (WG) has been found to be a highly effective method for improving a wide range of functional properties associated with plant protein. However, the bitter peptides formed during this process have an unpleasant bitterness. To provide a theoretical framework for de-bittering techniques, this study examined the modulation of bitterness intensity in wheat gluten hydrolysates (WGHs) by manipulating enzyme cleavage sites and degree of hydrolysis (DH). It was found that the bitter peptide's release content increased significantly, and the bitterness threshold decreased markedly with increasing DH. Furthermore, the structure-bitterness threshold association of bitter peptides was investigated. The results indicated that peptide segments in molecular weights (MW) from 500 to 1000 exhibited the greatest influence on bitterness threshold compared to peptides with other MWs. The percentage of total hydrophobic amino acid content and position of some hydrophobic amino acids in the amino acid sequence had a significant effect on the bitterness threshold. Finally, 47 peptides were identified by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis. These peptides were mainly small peptides with less than 13 amino acid residues and MW below 1500 Da, and most of them had Q values higher than 5855 J/mol.