Total Free Amino Acid Content Research Articles

Multicontamination Toxicity Evaluation in the Model Plant Lactuca sativa L.

Many contaminated soils contain several toxic elements (TEs) in elevated contents, and plant-TE interactions can differ from single TE contamination. Therefore, this study investigated the impact of combined contamination (As, Cd, Pb, Zn) on the physiological and metabolic processes of lettuce. After 45 days of exposure, TE excess in soil resulted in the inhibition of root and leaf biomass by 40 and 48%, respectively. Oxidative stress by TE accumulation was indicated by markers-malondialdehyde and 5-methylcytosine-and visible symptoms of toxicity (leaf chlorosis, root browning) and morpho-anatomical changes, which were related to the change in water regime (water potential decrease). An analysis of free amino acids (AAs) indicated that TEs disturbed N and C metabolism, especially in leaves, increasing the total content of free AAs and their families. Stress-induced senescence by TEs suggested changes in gas exchange parameters (increase in transpiration rate, stomatal conductance, and intercellular CO2 concentration), photosynthetic pigments (decrease in chlorophylls and carotenoids), a decrease in water use efficiency, and the maximum quantum yield of photosystem II. These results confirmed that the toxicity of combined contamination significantly affected the processes of lettuce by damaging the antioxidant system and expressing higher leaf sensitivity to TE multicontamination.

Potential of Subcritical Water Hydrolysis to Valorize Low-Valued Ray-Finned Fish (Labeobarbus nedgia): Effects of Hydrolysis Temperature and Pressurization Agent.

Subcritical water (SCW) hydrolysis was applied to valorize the low-valued ray-finned fish (Labeobarbus nedgia) into valuable protein hydrolysates, employing N2 and CO2 as pressurization agents at varying temperatures (140, 160, 180, and 200 °C). The degree of hydrolysis (DH) and total free amino acid content increased with temperature for both pressurizing agents. The highest DH (54.5 ± 0.4%) and total free amino acid content (210 ± 1 mg/gprot) were observed at 200 °C when CO2 gas was used as the pressurizing agent. Predominantly, glycine and alanine were released for both pressurizing agents. The antioxidant activity, evaluated through three different assays, increased with temperature and was found to be the highest at 200 °C. This study illustrated the advantages of the intensified SCW technology by using CO2 as a pressurization agent in valorizing low-valued ray-finned fish (Labeobarbus nedgia), as animal residue rich in proteins, for the production of valuable protein hydrolysates with a high fraction of valuable free amino acids, which could offer potential applications as a functional ingredient in the food industry.

Study on the Digestion-Induced Changes in the Characteristics and Bioactivity of Korean Native and Overseas Cattle-Derived Peptides.

This study was conducted to compare and analyze the changes in the biochemical characteristics and biological activity of peptide extracts derived from Chickso, Hanwoo, and Wagyu beef during digestion. The results of the in vitro digestion analysis revealed that the digestion rate, total free amino acid content, and antioxidant and antihypertensive activities of Chickso loin and shank myofibrillar proteins were significantly higher (p<0.05) than those of Hanwoo and Wagyu loin and shank myofibrillar proteins. Particularly, the peptide extracts of Chickso loin and shank had a high angiotensin-converting enzyme inhibitory activity. In mice in vivo digestion experiment, the blood serum of mice fed with Chickso loin peptide extract (<10 kDa) showed the highest antioxidant enzyme activity. Thus, Chickso peptide extracts were deemed to be similar or more bioactive than Hanwoo and Wagyu peptide extracts, and can be used as bioactive materials.

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.

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.

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.

Effects of the kinetic pattern of dietary glucose release on nitrogen utilization, the portal amino acid profile, and nutrient transporter expression in intestinal enterocytes in piglets

BackgroundPromoting the synchronization of glucose and amino acid release in the digestive tract of pigs could effectively improve dietary nitrogen utilization. The rational allocation of dietary starch sources and the exploration of appropriate dietary glucose release kinetics may promote the dynamic balance of dietary glucose and amino acid supplies. However, research on the effects of diets with different glucose release kinetic profiles on amino acid absorption and portal amino acid appearance in piglets is limited. This study aimed to investigate the effects of the kinetic pattern of dietary glucose release on nitrogen utilization, the portal amino acid profile, and nutrient transporter expression in intestinal enterocytes in piglets.MethodsSixty-four barrows (15.00 ± 1.12 kg) were randomly allotted to 4 groups and fed diets formulated with starch from corn, corn/barley, corn/sorghum, or corn/cassava combinations (diets were coded A, B, C, or D respectively). Protein retention, the concentrations of portal amino acid and glucose, and the relative expression of amino acid and glucose transporter mRNAs were investigated. In vitro digestion was used to compare the dietary glucose release profiles.ResultsFour piglet diets with different glucose release kinetics were constructed by adjusting starch sources. The in vivo appearance dynamics of portal glucose were consistent with those of in vitro dietary glucose release kinetics. Total nitrogen excretion was reduced in the piglets in group B, while apparent nitrogen digestibility and nitrogen retention increased (P < 0.05). Regardless of the time (2 h or 4 h after morning feeding), the portal total free amino acids content and contents of some individual amino acids (Thr, Glu, Gly, Ala, and Ile) of the piglets in group B were significantly higher than those in groups A, C, and D (P < 0.05). Cluster analysis showed that different glucose release kinetic patterns resulted in different portal amino acid patterns in piglets, which decreased gradually with the extension of feeding time. The portal His/Phe, Pro/Glu, Leu/Val, Lys/Met, Tyr/Ile and Ala/Gly appeared higher similarity among the diet treatments. In the anterior jejunum, the glucose transporter SGLT1 was significantly positively correlated with the amino acid transporters B0AT1, EAAC1, and CAT1.ConclusionsRational allocation of starch resources could regulate dietary glucose release kinetics. In the present study, group B (corn/barley) diet exhibited a better glucose release kinetic pattern than the other groups, which could affect the portal amino acid contents and patterns by regulating the expression of amino acid transporters in the small intestine, thereby promoting nitrogen deposition in the body, and improving the utilization efficiency of dietary nitrogen.

The Effects of Brassinosteroids on Nitrogen Utilization in Rice

Nitrogen and brassinosteroids (BRs) play a vital role in modulating the growth, development, and yield of rice. However, the influences of BRs on nitrogen assimilation and metabolism in rice are not fully understood. In this study, we analyzed the impact of BRs on nitrogen utilization in rice using the indica variety ‘Zhongjiazao 17’ and the japonica variety ‘Nipponbare’ in hydroponic conditions. The results showed that BR treatment could efficiently elevate nitrate and ammonium nitrogen accumulation in both shoots and roots. Furthermore, some genes involved in the uptake of nitrate and ammonium in roots were stimulated by BRs, though we noted subtle variances between the two rice cultivars. Moreover, BRs augmented the activity of nitrate reductase (NR) and glutamine synthetase (GS) in roots, along with NR in shoots. Interestingly, BRs also spiked the total free amino acid content in both the shoots and roots. Gene expression analysis uncovered a robust induction by BRs of NR genes and GS-related genes in the roots of both ‘Nipponbare’ and ‘Zhongjiazao 17’. Collectively, our data suggest that BRs significantly enhance the accumulation of both nitrate and ammonium in rice and trigger a series of reactions related to nitrogen utilization.

The impact of processing technology on microbial community composition and functional properties of Beninese maize ogi

Traditionally fermented maize starch, called ogi, is produced to prepare akpan, a yoghurt-like street food widely consumed in Benin. Current maize ogi production practices were compared to assess the impact of different processing technologies on the characteristics of the fermented product as a basis to determine best practices. Maize starch slurry samples were collected from processors in five municipalities in southern Benin and analysed before fermentation (starch samples) and after spontaneous fermentation (ogi samples). Four technological pathways for maize starch production were distinguished based on variations in the duration of steeping the grains, which ranged from 6 to 72 h, and whether or not kneading of the wet flour before filtration was practised. Six categories of maize ogi were derived from the four technology groups based on the duration of the fermentation, which lasted from 6 to 24 h. The average pH of maize starch varied from 3.2 to 5.3, with the lowest values for the two technology groups that also had the highest lactate concentrations (9–11.8 g/L). The six maize ogi categories had a pH ranging from 3.1 to 4.0. Viable plate counts of lactic acid bacteria were similar for maize starch samples and for ogi samples, whereas yeast counts showed clear differences. Members of the genera Limosilactobacillus, Lactobacillus, Weissella, Streptococcus and Ligilactobacillus, dominated the bacterial community in maize starch, and were also dominant in maize ogi. The members of the genera dominating the fungal community in maize starch were also dominant in maize ogi, except for Aspergillus and Stenocarpella spp., which decreased in relative abundance by fermentation. The highest total free essential amino acid concentration was 61.6 mg/L in maize starch and 98.7 mg/L in ogi. The main volatile organic compounds in maize starch samples were alcohols, esters, and carboxylic acids, which also prevailed in maize ogi samples. The results indicate that the characteristics of traditional maize ogi depend on the processing technologies used to produce the maize starch before the intentional fermentation into ogi, with no clear-cut connection with the production practices due to high variations between samples from the same technology groups. This revealed the importance of a standardized maize starch production process, which would benefit controlling the starch fermentation and the characteristics of maize ogi. Further research is needed to understand the hidden fermentation during maize starch production for determination of the best practices that support the production of quality maize ogi.

Effects of soybean cultivar and starter strain on biogenic amines formation during Cheonggukjang fermentation

Cheonggukjang, a traditional Korean fermented seasoning, contains biogenic amines (BAs). This research aimed to explore the effects of soybean cultivar, strain, and temperature on BAs formation during Cheonggukjang fermentation. Moisture, pH, total aerobic plate count, and protease activity were measured. Free amino acids (FAAs) and BAs were determined by high-performance liquid chromatography. Total FAA and BA contents tended to increase with fermentation time. Total BAs in the samples initially ranged from 112.65 to 153.05 mg/kg and ultimately increased to 155.72–614.28 mg/kg at 25 °C and 201.95–738.39 mg/kg at 37 °C, respectively. Bacillus licheniformis-inoculated samples had the highest total BA content (over 400 mg/kg) after 96 h of fermentation. Final histamine content in cv. ‘Somoktae’-made samples generally exceeded that in samples produced by the other two cultivars. These findings indicate that soybean cultivar, strain, and fermentation temperature all play pivotal roles in controlling the contents of BAs in Cheonggukjang.

Effects of Dietary Eucommia ulmoides Leaf Extract Supplementation on Growth Performance, Meat Quality, Antioxidant Capacity, and Lipid Metabolism of Finishing Pigs.

This study aimed to investigate the effects of dietary Eucommia ulmoides leaf extract (ELE) on meat quality, antioxidant capacity, and lipid metabolism in finishing pigs. A total of 240 "Duroc × Landrace × Yorkshire" crossbred pigs with an initial weight of 74.70 ± 0.77 kg were randomly assigned to two groups: control group and 0.2% ELE group, with each group containing 10 replicates of 12 pigs per pen (half barrows and half gilts). The data showed dietary 0.2% ELE supplementation did not affect growth performance but tended to reduce the backfat thickness of the finishing pigs (p = 0.07). ELE diets increased pH value (p < 0.05) and meat color score (p = 0.01) and decreased 45 min L* value (p < 0.05), 24 h L* value (p = 0.01), pressurization loss (p = 0.01), and 24 h drip loss (p < 0.05) in longissimus dorsi (LD) muscle, accompanied by an increased (p < 0.05) proportion of monounsaturated fatty acids (MUFA) and decreased polyunsaturated fatty acids (PUFA) (p = 0.06) and n-6/n-3 PUFA ratio (p = 0.05) compared to controls. In addition, ELE supplementation increased inosine monophosphate (IMP) (p = 0.01), sweet amino acids (AAs) (p < 0.05), and total free AA content (p = 0.05) in LD. Meanwhile, increased activity of glutathione peroxidase (p < 0.05) and superoxide dismutase (p < 0.01) in both serum and LD muscle and decreased malondialdehyde content (p < 0.01) in LD muscle were detected with ELE treatment. Moreover, pigs fed ELE had a higher total protein (p < 0.01), albumin (p < 0.05), and high-density lipoprotein cholesterol (p < 0.05) and a lower total cholesterol (p < 0.01) and triacylglycerols (p = 0.06) in serum. Consistently, significant effects of dietary ELE were observed on the relative mRNA expression of lipid metabolism in the backfat and the LD muscle, respectively. ELE attenuated lipogenic processes in backfat, decreasing the relative expression of acetyl-CoA carboxylase and upregulating the relative expression of adipose triacyl glyceride lipase, carnitine palmitoyl transferase 1B, and fatty acid-binding protein 4 (p < 0.05). ELE also decreased the relative expression of CCAAT/enhancer-binding protein α (p < 0.05), fatty acid translocase (p < 0.05), carnitine palmitoyl transferase 1B (p < 0.01), and adipose triacyl glyceride lipase (p < 0.05) in LD muscle (p < 0.05). More specifically, lipogenesis appeared to be inhibited in both LD muscle and backfat, with the difference being that lipolysis was enhanced in backfat and inhibited in LD muscle. In conclusion, dietary ELE supplementation can potentially enhance carcass traits, sensory quality, and nutritional value of pork without negatively affecting intramuscular fat content. The underlying mechanism for these positive effects may be linked to the alterations in lipid metabolism and increased antioxidant capacity induced by ELE.

The Biochemical Composition and Quality of Adult Chinese Mitten Crab Eriocheir sinensis Reared in Carbonate-Alkalinity Water

Saline–alkaline aquaculture has become an important breakthrough in expanding the space available for aquaculture in China. However, the biochemical composition and quality of Eriocheir sinensis reared in carbonate alkalinity water are still unclear. Therefore, this study investigated the edible yield, coloration, and nutritional and flavor quality of Eriocheir sinensis. A significantly lower gonadosomatic index (GSI), meat yield (MY), and total edible yield (TEY) were detected in intensive pond (IP) samples than those in semi-intensive reed wetland (SIWR) (p &lt; 0.05). Six color parameters in the hepatopancreas (p &lt; 0.05) differed between IP and SIRW. The contents of crude protein and fat in the female hepatopancreas of IP were significantly higher than those in SIRW (p &lt; 0.05). The concentrations of total monounsaturated fatty acids (∑MUFA), total essential fatty acids (∑EFA), and hypocholesterolaemic/hypercholesterolaemic ratio (h/H) in the female edible tissues checked were higher in IP than those in SIRW, with significant differences including ∑MUFA in the hepatopancreas and ovary, ∑EFA in the muscle, and h/H in the ovary (p &lt; 0.05). Higher total free amino acid (∑FAA) contents of muscle were detected in SIRW than that in IP samples. Significantly higher K, Ca, Mg, Fe, and Zn contents in the ovary were detected in SIRW samples compared to IP (p &lt; 0.05). Overall, Eriocheir sinensis reared in carbonate-alkalinity water is an important source of nutrients.

Investigation of stimulated growth effect by application of L-aspartic acid on poplar

Poplar is an important resource for the production of wood-based products. L-aspartic acid (Asp) is a proteinogenesis amino acid that plays a critical role in cell growth modulation and stress response. Also, Asp is widespread in the commonly used amino acid-based biostimulant products. However, its effects on poplars remain largely unknown. To address this issue, we applied different concentrations of Asp to poplar seedlings under N reduction conditions (simulating low N availability status), and assessed the effects of Asp on poplar growth and development. Our results showed that supplement of Asp at an appropriate concentration, that is, 0.5 mM in the present study, had the best growth-promoting effect on poplars. It significantly increased poplar biomass and height, and simultaneously elevated the photosynthetic parameters, the chlorophyll content and total free amino acid content, as well as the activity of N metabolism-related enzymes in poplars-treated with Asp in comparision with the control plants without Asp addition. Furthermore, the expression of Asp-metabolism pathway genes (AspAT1, AspAT6, AspAT10, AK1, ASS1 and ASS2), key chlorophyll synthesis gene (LHCB3) and cell division gene (CYCD3) was all dramatically upregulated in response to Asp application, suggesting that Asp-induced effect invoked photosynthesis activation and metabolism reprogramming. More interestingly, our results showed that the levels of various phytohormones, such as auxin and cytokinins were remarkably altered, and key auxin transport gene (PIN1c-2), auxin conjugation gene (GH3.6–2) were induced by Asp treatment, indicative of the possible involvement of plant hormones under the effect of Asp, especially fine-tuning auxin homeostasis by forming IAA-Asp conjugates to store auxin and catabolizing IAA-Asp to release auxin, may account for Asp-mediated growth modulation to an extent in poplars. Our study provides a novo insight into the growth promotion effect of Asp on poplars, especially, when the N source is limited, even though the underlying mechanism of Asp-induced stimulation action needs further in-depth investigation.

Physiological and transcriptomic regulation of Populus simonii fine roots exposed to a heterogeneous phosphorus environment in soil

Soil phosphorus (P) is usually limited and heterogeneously distributed. However, the physiological and transcriptional mechanisms of the woody plant fine roots to heterogeneous P are still unclear. In this study, a split-root system was used to simulate a heterogeneous P environment; that is, half of the fine roots of Populus simonii were grown under normal Pi conditions (2 mM, Hetero-NP), and the other half were grown under low Pi conditions (0.2 mM, Hetero-LP). Subsequently, the physiological and transcriptomic responses of the fine roots were determined under Hetero-NP and Hetero-LP conditions. The concentrations of ATP, malic acid and citric acid in the Hetero-LP region were lower than those in the Hetero-NP region, but the activity of APs was higher. P. simonii fine roots in the Hetero-NP or Hetero-LP region had larger fine root surfaces and SRL, as well as higher malic acid, citric acid, JA and SA concentrations, than those in the homogeneous Pi supply (Homo-NP or Homo-LP). In addition, the soluble protein and total free amino acid concentrations, as well as the AP, PEPC and MDH activities of P. simonii fine roots in Hetero-NP or Hetero-LP were higher than those in Homo-NP but lower than those in Homo-LP. GO, KEGG and MapMan analyses of the differentially expressed genes revealed that the genes in the “metabolic process” term and “plant hormone signal transduction” pathway, as well as in the “RNA”, “protein” and “signalling” categories, play key roles in the response of P. simonii fine roots to heterogeneous Pi. Our results indicated that the response of P. simonii fine roots to Hetero-NP or Hetero-LP differ due to local and systematic regulation. Phytohormones and the MAPK signaling system are involved in the local and systematic response of P. simonii fine roots to heterogeneous Pi supplies by promoting fine root elongation and regulating metabolic processes. Taken together, the findings of this study provide new insights into the response of woody plant fine roots to heterogeneous Pi.

Comparing Physicochemical Properties, Fatty Acid Profiles, Amino Acid Composition, and Volatile Compounds in Dry-Cured Loin: The Impact of Different Levels of Proteolysis and Lipid Oxidation.

The aim of this study is to compare the quality characteristics of dry-cured loins with different levels of proteolysis and lipid oxidation and to investigate the relationship between these factors on quality characteristics. The dry-cured loins were divided into four groups [proteolytic index (PI) and 2-thiobarbituric acid reactive substances (TBARS) of high levels (HH), PI of high level and TBARS of low level (HL), PI of low level and TBARS of high level (LH), and PI and TBARS of low levels (LL)] based on the proteolysis index and TBARS. Moisture, protein, and fat content were all significantly influenced by proteolysis and lipid oxidation (p<0.05). The total fatty acid content in the high proteolysis groups (HH and HL) was significantly lower than that in the low proteolysis groups (LH and LL; p<0.05). For total free amino acid content, HH was the highest, and LL was the lowest (p<0.05). On the other hand, there was no significant difference between HL and LH (p>0.05). In the amount of total volatile compounds, there was no significant difference between HH and HL (p>0.05), but LH and LL significantly differed (p<0.05). In conclusion, proteolysis and lipid oxidation can influence the quality characteristics of dry-cured loin. Additionally, proteolysis might be as influential in generating volatile compounds as lipid oxidation.

Improved umami taste of the enzymatic hydrolysate of soybean protein isolate by Corynebacterium glutamicum P-45 fermentation

Improving the umami taste of seasoning is an important topic of discussion in the current scenario based on the conventional technology of using soybean protein isolates (SPI) as proposed as the base material for seasoning. In this study, a novel SPI seasoning was created by fermenting the SPI hydrolysate of Corynebacterium glutamicum to increase the umami taste of its fermented products. The differences between traditional SPI enzymatic hydrolysate fermentation (Sample S), traditional C. glutamicum fermentation (Sample F), and the aforementioned novel fermentation (Sample SF) were investigated. The results showed that Sample SF had the best umami taste, saltiness, and richness, which was compared with sample S and F showing significant differences, respectively (P < 0.05). Succinic acid, lactic acid, and acetic acid were the main organic acids in the seasonings, accounting for 92.24% of the total organic acids. The total fresh-sweet free amino acids content of sample SF was 7.22 and 2.15 times that of samples S and F, respectively, and 5′-nucleotide content was 2.85 and 2.35 times that of Samples S and F, respectively. Glu, 5′-inosine monophosphate, and 5′-guanosine monophosphate contents contributed remarkably to the umami taste of the seasoning (P < 0.05). Furthermore, among all the detected umami compounds, 18 conformed the variable important projection (VIP) values > 1.0. Therefore, SPI hydrolysate fermentation by C. glutamicum may improve the umami flavor of fermented products. This study presents a novel method for producing new SPI-containing seasonings on a commercial scale.

Response studies of nano-sulphur on nutrient uptake, sulphur fractions, yield and quality parameters of peanut (Arachis hypogaea L.)

An attempt was made to study the response of nano-sulfur in groundnut using four levels of nano-sulfur (NS) and conventional sulfur (CS) fertilizers in a completely randomized block design and replicated thrice. The results indicated that application of nano-sulfur @ 30 kg S ha−1 recorded 0.76 mg root sulfur uptake plant−1, 40.5 mg shoot sulfur uptake plant−1, 14.9 mg kernel sulfur uptake plant−1, and 3.09 mg shell sulfur uptake plant−1 higher in comparison to conventional sulfur @ 40 kg S ha−1 recorded root, shoot, kernel and shell sulfur uptake of 0.53, 35.8, 11.4 and 2.46 mg plant−1, respectively. The highest pod yield was recorded at 12.4 g plant−1 with nano-sulfur application @ 30 kg S ha−1 when compared to conventional sulfur @ 40 kg S ha−1 registered at 10.7 g plant−1. Quality parameters such as oil, crude protein, methionine, cysteine, and total free amino acid content were recorded highest under nano-sulfur application @ 30 kg S ha−1 i.e. 48.3%, 27.2%, 3.44 mg g −1, 1.89 mg g−1 and 46.3 mg g−1 respectively whereas conventional sulfur @ same set of sulfur treatment observed (46.7% oil, 25.1% crude protein, 3.16 mg methionine g−1, 1.75 mg cysteine g−1, and 39.6 mg total free amino acids g−1. Finally, the results concluded that the application of nano-S @ 30 kg S ha−1 is sufficient to attain higher sulfur use efficiency with a reduction of sulfur fertilizer to the tune of 25% besides augmenting the soil sulfur reserve without harming the environment.

The flavor substances changes in Fuliang green tea during storage monitoring by GC–MS and GC-IMS

To study the effect of storage (for 0, 3, 6, and 12 months) on the flavor of green tea (GT), we monitored the volatile organic compounds (VOCs) in GT through gas chromatography (GC) combined with ion mobility spectrometry and headspace solid-phase micro extraction, GC–MS (mass spectrometry). Then, relative odor activity value (ROAV) was applied to analyze the aroma contribution of the VOCs. During storage, the polyphenol and caffeine contents gradually decreased from 22.38 % to 18.51 % and from 4.37 % to 3.74 %, respectively, and the total soluble sugar first increased and then decreased (from 4.89 % to 7.16 % and then 5.02 %). Although the total free amino acid contents showed a fluctuating trend, the content of cysteamine increased gradually. The contents of VOCs with positive contribution to GT aroma, including linalool, geraniol, nonanal, and 6-methyl-5-hepten-2-one, decreased. They also contributed less in the ROAV after storage. The ROAVs of nonanal, linalool, and geraniol decreased from 3.37 to 0.79, from 100 to 38.21, and from 2.98 to 1.8, respectively, after 12 months of storage. Principal component analysis can be used to identify the samples with different storage durations based on these data. Given the increase in amount of cysteamine and decrease in that of linalool oxide, oxidation may be not the only factor responsible for tea quality in storage.

Effects of vitamin C combined with sodium alginate on serum biochemistry, oxidative stress, gill tissue morphology, and muscle quality of pearl gentian grouper during waterless transport.

This research examined the effects of sodium alginate (SA) and vitamin C (Vc) soaking of pearl gentian grouper before waterless transportation from the perspectives of serum parameters, oxidative stress, muscle quality, and gill tissue morphology. After the fish reached semi-dormancy with a cooling rate of 3°C/h, fish (420 ± 25g) were distributed to 4 treatments as follows: S1 group (50mg/L Vc and 0.1% SA were added), S2 group (50mg/L Vc and 0.3% SA were added), S3 group (50mg/L Vc and 0.5% SA were added), and control group (without soaking in protective fluid). After oxygenated packaging, samples were taken at 0, 8, and 16h of waterless transportation and 12h after rehydration, respectively. It was found that after 16h of waterless transport, compared with the control group, cortisol, glucose, blood urea nitrogen (BUN), uric acid (UA), creatinine (CREA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and malondialdehyde (MDA) levels were significantly decreased (p < 0.05), while albumin, lysozyme (LZM), muscle pH, and total free amino acid (TFAA) contents were significantly elevated (p < 0.05) in the S3 group. Moreover, by gill tissue microscopy, it was found that the protective solution of group S3 did not cause serious deleterious morphological changes to the gill epithelium. The results showed that the grouper was soaked by protective fluid before waterless could maintain surface moisture, reduce gill and kidney function and oxidative stress damage, and maintain the stability of muscle quality. This study provides a novel transportation method for waterless preservation, which helps to reduce transportation costs and improve transportation efficiency.

An insight into the quality formation of egg-white sufu based on the dynamic changes of protease activity, physicochemical properties and texture

Sufu is a delicious traditional Chinese food, mainly produced by fermentation using soybeans as raw material. Egg white is rich in protein and is theoretically an excellent material for sufu processing, however there are few reports on egg-white sufu (EWS) currently, and no such product is available on the market. In this paper, a novel sufu was processed with egg white as main material, and the formation mechanism of its unique quality was explored by monitoring the dynamic changes in the pre-fermentation and post-fermentation stages. The dynamic change curve of protease activity showed an “S” shape, with a peak of 32.33 U/mL on the 4th day of pre-fermentation stage. After a 4-day pre-fermentation and 90-day post-fermentation, most of the proteins in the EWS had been hydrolyzed, and the sufu was moderately soft and delicate in texture, with a hardness of 950.3 g and a total free amino acid content of 19.863 mg/g. SEM and SDS-PAGE detections suggested that the proteins in EWS had been extensively degraded, which led to the formation of its unique texture and flavor. The EWS was slightly better than soybean sufu in terms of texture, fragrance and mouthfeel, with flavor compounds mainly composed of aldehydes and alcohols, resulting in a slightly higher total sensory evaluation score.