Total Free Amino Acid Content Research Articles

효소 및 미생물 복합체를 사용한 인비트로 루왁 커피의 품질 특성

In vitro luwak coffee was produced using enzyme-microbial complexes. The coffee quality of non-fermented coffee beans (NFC) and fermented coffee beans (FC) was compared. The total free amino acid content was higher in FC than in NFC. The levels of glutamic acid and γ-amino-n-butyric acid in NFC were higher than those in FC; however, the contents of essential amino acids, such as lysine, leucine, and valine, in FC were higher than in NFC. During fermentation, the sucrose content decreased, whereas the fructose and glucose contents increased (p<0.001). The chromaticity of the coffee extract showed higher lightness (L), redness (a), and yellowness (b) values in FC than those in NFC. The caffeine content was significantly lower in FC (696.94±0.04 μg/mL) compared to that in NFC (1,130.22±1.55 μg/mL) (p<0.001). Conversely, the polyphenol and chlorogenic acid contents were significantly higher ​​in NFC than in FC (p<0.001). Electronic nose analysis indicated considerable differences between the volatile aromatic components in NFC and FC. Sensory scores were significantly higher for FC than those for NFC. Therefore, the fermentation of coffee beans using enzyme-microbial complexes altered the chemical components, which promoted the Maillard reaction during the coffee bean roasting process. These results suggest the possibility of producing in vitro luwak coffee with better flavor and lower caffeine content.

효소 및 미생물 복합체를 사용한 인비트로 루왁 커피의 품질 특성

In vitro luwak coffee was produced using enzyme-microbial complexes. The coffee quality of non-fermented coffee beans (NFC) and fermented coffee beans (FC) was compared. The total free amino acid content was higher in FC than in NFC. The levels of glutamic acid and γ-amino-n-butyric acid in NFC were higher than those in FC; however, the contents of essential amino acids, such as lysine, leucine, and valine, in FC were higher than in NFC. During fermentation, the sucrose content decreased, whereas the fructose and glucose contents increased (p<0.001). The chromaticity of the coffee extract showed higher lightness (L), redness (a), and yellowness (b) values in FC than those in NFC. The caffeine content was significantly lower in FC (696.94±0.04 μg/mL) compared to that in NFC (1,130.22±1.55 μg/mL) (p<0.001). Conversely, the polyphenol and chlorogenic acid contents were significantly higher ​​in NFC than in FC (p<0.001). Electronic nose analysis indicated considerable differences between the volatile aromatic components in NFC and FC. Sensory scores were significantly higher for FC than those for NFC. Therefore, the fermentation of coffee beans using enzyme-microbial complexes altered the chemical components, which promoted the Maillard reaction during the coffee bean roasting process. These results suggest the possibility of producing in vitro luwak coffee with better flavor and lower caffeine content.

Relationship between physicochemical properties and microbial structural distribution of Chinese-style and Salami fermented sausages

This study insightfully analyzed the relationship between chemical composition change, volatile flavor compounds (VFCs) and microbial structural distribution of Chinese-style (CFS) and Salami fermented sausages (WFS) during their fermentation processes (FP). The results showed pH, acid and peroxide values of CFS were higher than WFS during whole FP (38 d). At the end of fermentation (38 days), the pH value of CFS and WFS were 5.70 ± 0.01 and 5.43 ± 0.01, respectively. The acid value was 9.89 ± 0.38 and 6.29 ± 0.28 mg/g, respectively. The peroxide value was 0.21 ± 0.01 and 0.14 ± 0.01 g/100g, respectively. During 0–13 d, moisture contents of CFS were higher than WFS, while opposite in 14–38 d. Nitrite contents of WFS were higher than CFS. The total free-amino acid contents of CFS were significantly lower than WFS (p < 0.05). The six groups of main VFCs in the two sausages were aldehydes, acids, alcohols, esters, ketones and hydrocarbons, respectively, and the contents of ketone in CFS were higher than WFS. However, the bacterial abundance in CFS increased gradually, while that in WFS's increased firstly and then decreased. The abundances and diversities of fungi in WFS were higher than CFS. In brief, microbial structural distribution formed an obvious impact on the chemical composition quality of fermented sausages, the above results provided data support for the production improvement of Chinese-style and Salami fermented sausages.

Nutritional composition of the wild variety of edible vegetables consumed by the tribal community of Raipur, Chhattisgarh, India

Humans established relations with food with their existence on earth. In various parts of the world, different types of vegetation are used as food material. Chhattisgarh, where numbers of tribes exist and used a leafy portion of various plants as a food material. The present study evaluated the total protein, total carbohydrate, and total free amino acid content in leafy vegetables used in Chhattisgarh. Total protein was estimated by Lowry method, while total carbohydrate and free amino acid content by Anthrone method and spectrophotometric method. The result showed highest protein contained in Tamarindus indica (103.98 ± 2.34 μg/mg) followed by Moringa olerifera (99.86 ± 2.32 μg/mg), Cicer arietinum (95.53 ± 2.78 μg/mg). The highest carbohydrate content was observed in the leaf of Amaranthus viridis (116.26 ± 2.33 μg/mg of plant tissue) followed by Marsilea vestita with carbohydrate content (82.35 ± 1.55 μg/mg), Chorchorus olitorius with carbohydrate content (50.46 ± 2.23 μg/mg), and highest free amino acid content was recorded in the leaves of (232.33 ± 2.05 μg/mg of plant tissue) followed by Brassica oleracea (204.94 ± 1.25 μg/mg), Cucurbita maxima (85.67 ± 2.35μg/mg). The study’s finding confirmed that wild leafy vegetables utilized by the special community of this area play a significant role in their livelihood as those vegetables contain higher nutrient level compared to conventional crops. As per the data reported, more than one million people of this region suffer from malnutrition so present study is an approach to overcome the health issue of people of this region in a sustainable manner

Effect of Koji on Flavor Compounds and Sensory Characteristics of Rice Shochu

Koji is an important starter for rice shochu brewing and influences the rice shochu quality. Consequently, we studied the impacts of koji on the flavor compounds and sensory characteristics of rice shochu using molds Aspergillus kawachii SICC 3.917 (A-K), Aspergillus oryzae SICC 3.79(A-O), Aspergillus Niger CICC 2372 (A-N), Rhizopus oryzae CICC 40260 (R-O), and the traditional starter Qu (control). The effects of koji on the aroma components, free amino acids (FAAs), and overall sensory aspects of rice shochu were studied. These findings indicated that koji significantly affected the rice shochu's quality. The content of total FAAs in rice shochu A-K (30.586 ± 0.944 mg/L) and A-O (29.919 ± 0.278 mg/L) was higher than others. The content of flavor compounds revealed that the aroma of rice shochu with various koji varied greatly from the smells of alcohols and esters. Shochu A-O had a higher concentration of aroma compounds and it exhibited a strong aroma and harmonious taste compared with the others. This research using taste compounds, FAAs, flavor intensity, and partial least squares regression (PLSR) showed that shochu A-O appeared to possess the best sensory qualities, with elevated concentrations of alcohols and sweet FAAs and lesser concentrations of sour FAAs. Therefore, the A-O mold is promising for the manufacture of rice shochu with excellent flavor and sensory characteristics.

Comparative study between triploid and diploid oysters (Crassostrea gigas) on non-volatile and volatile compounds

The quality of diploid oyster (crassostrea gigas) decreased significantly during the breeding period, which reflected the quality advantage of triploid oyster. However, there were few comparative studies on flavor quality characteristics between diploid and triploid oysters. This study compared the non-volatile compounds and volatile compounds between triploid and diploid oysters. These results showed that the percentage of eicosapentaenoic acid (EPA) in diploid oysters (18.68 ± 0.26%) was significantly higher than that in triploid oysters (16.16 ± 1.61%). The content of inosincacid (IMP) in diploid oysters (16.13 ± 0.03 mg/100 g) was significantly lower than that in triploid oysters (22.27 ± 0.41 mg/100 g). Adenosine monophosphate (AMP) content (364.08 ± 0.48 mg/100 g), succinic acid content (1244.51 ± 24.81 mg/100 g), and total free amino acid content (638.34 ± 17.32 mg/100 g) were significantly higher than those of triploid oysters (248.85 ± 2.32 mg/100 g, 420.99 ± 8.76 mg/100 g, 552.71 ± 17.32 mg/100 g, respectively). The main volatile compounds in diploid and triploid Pacific oysters were alcohols, aldehydes, ketones and esters. The volatile compounds content in triploid oysters were higher than those in diploid oysters. This study will provide basic data of Pacific oyster flavor and essential for the flavor pattern of seafood.

The effect of seasonality on the biogenic amines, free amino acids, and physico-chemical composition of raw milk Fiore Sardo cheese produced in Sardinia (Italy)

The effect of seasonality on the content of biogenic amines (BA), compounds that could threaten food safety at a high level, were evaluated in Fiore Sardo, a typical artisanal raw sheep's milk cheese produced in Sardinia. The cheese samples collected from six farms, after four months of ripening, were manufactured from January to June. The relationship between the BA content, the free amino acid (FAA) concentration, and the physico-chemical composition (pH, a w , NaCl, humidity, and the fat and protein content) was considered. The FAA and BA contents were determined by HPLC-FL. The BA content and the other parameters analysed were significantly affected (p ≤ 0.000) by seasonality and the farm of origin. Despite the differences attributable to the producers, the seasonal variations of all the parameters considered followed the same trend. As the season changed, the level of total BA grew, reaching a mean content of 1402 ± 207 mg/kg in the samples produced in June, almost five times the mean value of those manufactured in January. The most represented biogenic amine was tyramine, followed by putrescine and cadaverine. Histamine was determined almost exclusively in some samples produced in the warmer months, while β-phenylethylamine and tryptamine were found in a low concentration or not detected. The winter products did not exceed the threshold of 900 mg/kg proposed for the total BA in food, while most of the samples manufactured in the hottest months exceeded this limit, posing a potential risk to consumers' health. The total FAA and BA content were correlated (p = 0.01), indicating that with the change of the season, proteolysis phenomena increased and made the precursor amino acids available for microbial decarboxylase activity. In addition, from January to June, the pH and fat levels grew, while those of a w , humidity and NaCl tended to decline. The study highlighted that as the season changed, the rise in temperature, probably combined with the increment of fat and decrement of NaCl content, could favour proteolysis phenomena and bacterial decarboxylase activity and, as a result, the escalation of BA production. Interventions in the production protocol to reduce the negative effect of seasonality on cheese safety are needed. In addition, in light of these results, it is possible to speculate that the rising temperature and the predicted lengthening of the warm season due to climate change, which also seems to affect the spring periods, could create the ideal conditions for the production of biogenic amines for an increasingly extended phase of the year.

Identification of free amino acids (FAA) that are important as major intracellular osmolytes in the estuarine Hong Kong oyster, Crassostrea hongkongensis

Crassostrea hongkongensis (Hong Kong oyster), a commercially valuable bivalve thriving in the estuaries along the northern coast of the South China Sea, is threatened by the increase of salinity during the dry season. It is essential to improve its hyper-salinity tolerance, which requires a clear understanding of the mechanism to regulate its osmotic balance. For this purpose, 25 free amino acids (FAA), the most critical intracellular osmolyte in bivalves, were quantified in gill, adductor muscle, and hemolymph of C. hongkongensis during abrupt salinity changes (18–6, 12, 24 and 30‰) by high-performance liquid chromatography-tandem mass spectrometry. Taurine, alanine and glycine were dominant FAA, contributing to total FAA contents that varied with salinities, no matter in gill, muscle or hemolymph. Under hypo-osmotic stress, total FAA contents decreased in gill and adductor muscle but increased in hemolymph, probably resulting from the extrusion of some FAA from tissues to prevent swelling of cells. And taurine contributed most significantly to the hypo-salinity response, which was mainly reflected by the remarkable increase in hemolymph at 8 h after the exposure to 6‰. By contrast, total FAA contents increased in gill, muscle, and hemolymph when transferred to hyper-salinity, suggesting the assumption that it increases the osmolality and subsequently prevents the cell shrinking. Alanine and glycine contributed most significantly to hyper-salinity response. Of the two, the former was more sensitive to hyper-osmotic stress for its rapid increase in gill within 8 h after the exposure to 24 and 30‰. An inverse pattern with most FAA was presented by ornithine, the intermediate of the urea cycle, which was probably associated with the FAA metabolism. This study identified the major FAA as intracellular osmolytes in C. hongkongensis and would benefit the further understanding of the regulatory mechanisms of oyster salinity acclimation.

Interactive effects of diet and water temperature on the nutritional value, flavor, and sensory quality in hybrid abalone (Haliotis. discus hannai ♀ × H. fulgens♂) meat

In commercial aquaculture, the phenomena of diet conversion and water temperature fluctuation commonly occur in abalone farming. The meat quality of abalone is affected by diet and temperature, and this in turn directly influences consumer acceptance of abalone products and financial returns to producers. The aim of this study was to investigate the impacts of diet (Gracilaria lemaneiformis vs artificial feed) and water temperature (low, 19 °C and high, 27 °C) on growth performance, nutritional value, flavor, and sensory quality of abalone. The results showed that artificial feed led to increases in growth, content of body protein, total free amino acids (TAA), delicious amino acids (DAA), volatile compounds (alcohols, acids, aromatic compounds, and esters), and sensory quality (hardness) of abalone meat. High temperature significantly decreased the growth, body moisture, n-3 polyunsaturated fatty acids, and hardness but increased the contents of DAA, TAA, alcohols, acids, and aromatic compounds in abalone meat. Our study suggests that high temperature significantly decreases the growth and nutritional value of abalone muscle but does provide a different mouthfeel and flavor for consumers, and nutrition-balanced artificial feed as the diet at a low water temperature maximizes the growth of abalone without sacrificing meat quality. The results may help to formulate an optimal feed strategy for farming industries throughout the abalone culture period, thereby allowing farmers to harvest premium quality abalone and elevate the market value of abalone products.

청태전의 제조연도에 따른 품질 특성 비교

This study examined the morphological, chemical, and sensory characteristics of cheongtaejeon (Korean traditional fermented ddeok-cha) to determine changes in the tea leaves according to the year of manufacture (aging 1-6 years). The weight and diameter of cheongtaejeon were observed to decrease due to reducing moisture during aging. Color evaluation of cheongtaejeon showed that the infused tea had a gradually decreasing Hunter L value, but the Hunter a and b values increased during aging. Total free amino acid contents were determined to increase during the aging process. However, the total phenolic and flavonoid contents of cheongtaejeon were found to fluctuate depending on the aging period. Most catechin contents decreased during aging, but the contents of gallic acid, catechin, and epicatechin gallate were found to be increased. The aged cheongtaejeon had a higher score for sensory parameters (color, taste, aroma, and overall acceptability) compared to the non-aged cheongtaejeon. Our results can be used as basic data to establish a standardized manufacturing method and improve the quality of cheongtaejeon.

Changes in Growth, Ionic Status, Metabolites Content and Antioxidant Activity of Two Ferns Exposed to Shade, Full Sunlight, and Salinity

The interactions between ferns and the environment have been frequently researched. However, detailed data on how ferns respond to specific stresses and a combination of stress factors during cultivation are lacking. This study assessed the effects of salinity and full sunlight and the combination of both stresses on the growth and selected metabolic parameters of two hardy ferns (Athyrium nipponicum cv. Red Beauty and Dryopteris erythrosora) under production conditions. Hardy ferns are highly interesting ornamental plants that can serve as a potential source of antioxidants for the pharmaceutical, cosmetic, and food industries. The results showed that in both ferns, salinity and salinity combined with full sunlight lowered the dry weight of the aerial part and potassium/sodium and calcium/potassium ratio compared with control plants. Salinity, full sunlight, and multi-stress did not affect the total polyphenol content in both ferns but increased the total free amino acids and flavonoids in D. erythrosora. In A. nipponicum cv. Red Beauty, all stressors decreased the total free amino acids content and the antioxidant activities determined by ABTS, DPPH, FRAP, and reducing power assays. By contrast, plants of D. erythrosora grown under full sunlight are characterized by higher antioxidant activities determined by DPPH, FRAP, and reducing power assays. Overall, a greater adaptive potential to abiotic stresses was found in D. erythrosora than in A. nipponicum cv. Red Beauty. Our findings shed some light on the physiological mechanisms responsible for sensitivity/tolerance to salinity, full sunlight, and combined stresses in hardy ferns.

Effects of temperature fluctuations on non-volatile taste compounds in tilapia fillets (Oreochromis niloticus)

In this study, the effect of temperature fluctuations on the taste quality of tilapia fillets during frozen storage was investigated. Major temperature-responsive factors included free amino acids (FAAs) and flavor nucleotides in fish fillets, which were identified using multidimensional infrared spectroscopy (MM-IR). The main FAA in tilapia fillets is a sweet amino acid (glycine). Compared with the control group, the umami FAAs and sweetness FAAs were significantly increased, and the total FAAs content increased to 1.30 times after the ninth fluctuation, reaching the highest level (611.16 ± 73.60 mg/100 g). Considering the equivalent umami intensity values, adenosine monophosphate and inosine monophosphate were retained during the first and second temperature fluctuations. In addition, the content of Na+, K+, and Ca2+ decreased (P < 0.05). Therefore, MM-IR is an effective method to identify taste components. With regard to taste quality, temperature fluctuations in the twofold range have an umami-enhancing effect.

Water-soluble total sugars and total free amino acids of the two varieties of teff [Eragrostic tef (Zuccagni) Trotter] cultivated in different regions of Ethiopia

ABSTRACT. Teff [Eragrostis tef (Zuccagni) Trotter] is cereal grain native to Ethiopia as staple food to millions of people. However, no research work has been reported for characterization with respect to water-soluble total sugars and total free amino acids in white and brown teff grains. The main objective of this study was to determine water-soluble total sugars and total free amino acids (TFAA) in the white and brown teff grain varieties. The determined water-soluble total sugar contents of white and brown teff grain sample extract was ranged between 2.69±0.12 – 4.56±0.08 g GE/100 g and 2.22±0.04 – 4.74±0.19 g GE/100 g, respectively. The mean TFAA contents for white and brown teff samples was found in the range between 181.4±30.0 – 638.9±42.6 mg AE/100 g and 471.7±37.0 – 927.1±32.4 mg AE/100 g, respectively. The mean value of the TFAA in brown teff samples was found higher than that of white teff samples. Pearson correlation was in the opposite direction, indicating that the biosynthetic pathways for the water-soluble total sugars and TFAA in both white and brown teff varieties might be opposite. Therefore, the present study indicated that teff is rich in the water-soluble total sugars and TFAA.&#x0D; &#x0D; KEY WORDS: Teff, Sugars, Amino acids, Glucose, Ninhydrin, UV-Vis spectrophotometry&#x0D; &#x0D; Bull. Chem. Soc. Ethiop. 2023, 37(2), 299-313. &#x0D; DOI: https://dx.doi.org/10.4314/bcse.v37i2.5

Comparison of physicochemical properties of pollen substitute diet for honey bee (Apis mellifera)

• Group I showed higher total free amino acid contents than Group II and Group III. • Group I showed alike nutrition content to the commercial bee diet. • AIGT + Soytide showed a high level of total free amino acid and organic acid. • AIGT + Soytide showed the highest contents of inorganic ions. Apis mellifera L., a globally important pollinator, is crucial in the maintenance of its colonies due to a variety of stresses. Healthy nutrition is believed to help grow their population and relieve the stressors. We used our-prepared and commercial diets, and the nutrition contents were then analyzed for free sugar, organic acids, free amino acids, inorganic ions, total polyphenols, vitamin C, and the pH. The total free sugar, organic contents, free amino acids, inorganic ions, and total polyphenols were in the range of 228.59 to 661.00, 0.91 to 20.60, 6.52 to 24.36, 10.25 to 27.61, and 1.65 to 10.17 mg/g, respectively. The highest contents of free sugar, organic acids, free amino acids, inorganic ions, and total polyphenols were found in YBNH (661 mg/g), Megabee (20.60 mg/g), Beebread (24.36 mg/g), AIGT + Soytide (27.61 mg/g), and Beebread (10.17 mg/g), respectively. The pH values were maintained at 4.45 to 5.70 among all ten samples. Group I showed the same level of total free sugars (Group II and Group IV), organic acids (Group II), inorganic ions (Group II, Group III, and Group IV), polyphenols (Group II), and pH (Group IV). For the total free amino acids, Group I showed a significantly higher ( P < 0.05) level than that of Group II and Group III. Group I had a comparable nutrition content to the commercial bee diet but had a higher total free amino acid content. High levels of inorganic ions, free amino acids, and organic acids were found in the AIGT + Soytide.

Bivalves Transmissible Neoplasia: Biochemical Aspects of Contagious Cancer in a Clam Macoma Balthica.

Occurring in marine invertebrates infectious haemic neoplasia (bivalves transmissible neoplasia, BTN) arises from genome instabilities leading to multilevel malfunctions and unregulated cell division of presumably haemocyte precursors. As its biochemical characterisation remains unknown, we here present the first data describing selected aspects of the physiology and biochemistry of the disease a in model clam Macoma balthica. We chose free amino acids (FAA) composition, mitochondrial respiration and enzymatic activity, oxidative stress enzymes activities and corticosteroids profile as markers of this contagious cancer. Selected markers were measured in neoplastic and healthy clams and two tissue types, haemolymph and solid tissue. FAA composition was assessed in the haemolymph samples using high performance liquid chromatography-mass spectrometry (LC/MS). Mitochondrial respiration analysis was performed on haemocytes using oxygen electrodes integrated system Seahorse XFp. Mitochondrial enzymes activities were measured using spectrophotometry (cytochrome oxidase, COX) and commercial kit (succinate dehydrogenase, SDH). Total Antioxidant Capacity (TAC), Acetylocholinesterase (AChE), Protein Carbonyl Content (CBO) and Malondialdehyde (MDA) levels were measured in the solid tissue using analytical kits, and glutathione (GSH) was measured spectrophotometrically. Corticosteroids profile, measured in the solid tissue, was obtained with Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (HPLC-ESI-MS/MS) technique. In both clam groups nine FAAs were detected with Asp, Glu, Pro, Ser constituting over 90% of total FAA content. Significantly higher Gln level was detected in BTN positive clams. In neoplastic clams, an impairment of mitochondrial metabolism was observed as a decrease in mitochondrial oxygen consumption and lower cytochrome c oxidase activity. In the neoplastic clams significantly higher concentration of low molecular weight antioxidants was found. Finally, we report high level of corticosterone and lower levels of dehydrocorticosterone, cortisol and cortisone in healthy clams and elevated cortisol level in BTN individuals. Neoplastic clams are characterized by altered mitochondrial metabolism, with a potential key role of glutamine (Gln) in cancer cells energy production. Despite low aerobic respiration, BTN cells have efficient antioxidative response to elevated concentration of ROS. Elevated cortisol level in BTN-positive clams may indicate an important role of this corticosteroid in cancer biochemistry. Thus, we here provide the first results of selected physiological and biochemical aspects of BTN, making an important step in studying cancer epidemiology in wildlife.

Dietary supplementation of kaempferol improved the growth, lipid metabolism and flesh quality of juvenile grass carp (Ctenopharyngodon idellus) based on metabolomics

Kaempferol is a common flavonoid with various biological and pharmacological functions. To investigate the effects of dietary kaempferol on growth, lipid metabolism and flesh quality of juvenile grass carp (Ctenopharyngodon idella), five diets with kaempferol inclusion at 0 (control diet), 0.2, 0.4, 0.6 and 0.8 g/kg were fed to fish (17.0 ± 0.2 g) for 60 days. The results indicated that dietary kaempferol level linearly affected weight gain (WG) and feed conversion ratio (FCR), and the supplementation of 0.6 g/kg, 0.8 g/kg kaempferol increased WG by 4.9 %, 5.6 % and decreased FCR by 0.08, 0.08, respectively. Flavor amino acids content and activities of superoxide dismutase, catalase and glutathione peroxidase in flesh were linearly increased, and total free amino acids content, hardness, chewiness and adhesiveness of flesh were linearly and quadratically increased with the increasing kaempferol level. Moreover, the increasing dietary kaempferol linearly decreased intraperitoneal fat ratio, malondialdehyde content in flesh and triacylglycerol and cholesterol in serum and liver. In metabolomics profiling of flesh, 102 and 133 named differential metabolites were identified in 0.4 g/kg and 0.8 g/kg kaempferol groups, and these metabolites were mainly involved in the second-grade pathways of “lipid metabolism” and “amino acid metabolism”. In gene expression, the mRNA levels of mammalian target of rapamycin (mTOR), catalase (CAT), peroxisome proliferators-activated receptor α (PPARα) in flesh as well as PPARα in liver were up-regulated, and FAS gene expression in liver was down-regulated by dietary supplementation of 0.4 and 0.8 g/kg kaempferol. In summary, dietary kaempferol improved the growth, lipid metabolism and flesh quality of juvenile grass carp, which might be associated with the insulin-like growth factor 1/mammalian target of rapamycin (IGF-1/mTOR), PPAR and nuclear factor-E2 related factor 2 (Nrf2) pathways. The recommended supplementation level of kaempferol in diet was 0.8 g/kg for juvenile grass carp.

Improving tea (Camellia sinensis) quality, economic income, and environmental benefits by optimizing agronomic nitrogen efficiency: A synergistic strategy

Tea is a perennial crop widely cultivated globally. Excessive application of fertilizers is a common practice among tea farmers; however, this lowers the tea quality and consequently income and also results in serious environmental impacts. Agronomic efficiency is a vital indicator of tea yield, quality, and its environmental impact. Maximizing tea quality and economic benefits while minimizing its harmful environmental impact is an important strategy for sustainable agriculture; however, corresponding goal-oriented solutions are lacking. In this study, we used representative tea quality indicators (free amino acids), income, and global warming potential (GWP) to analyze the possibility of multi-objective synergy and explore the feasibility of achieving agronomic efficiency using the Pareto model. The Pearson correlation results indicated that the agronomic efficiency of N (AEN) was significantly (p < 0.05) associated with the free amino acid content, income, and GWP of tea. When AEN increased from 2.6 to 5.5 kg kg−1, free amino acid content and income increased by 37.2% and 80.2%, respectively, while GWP decreased by 50.9% for optimized management compared with those for conventional management using the Pareto multiple-objective optimize model. Concurrently, N fertilizer application rate was reduced from 491.4 to 237.0 kg ha−1. The results of the structural equation model revealed that the AEN had a positive pathway for income and total free amino acids content. N fertilizer application rate directly affected the GWP and AEN and indirectly affected tea leaf-free amino acid levels and production income. Reducing nitrogen fertilizer rate helps to increase AEN and further mitigates GWP and improves economic benefits and free amino acid content of tea. These findings outline a reference for tea farmers and can provide basic guidelines for a sustainable tea industry.

Changes in Protein Degradation and Non-Volatile Flavor Substances of Swimming Crab (Portunus trituberculatus) during Steaming.

To investigate the effect of steaming time (0, 5, 10, 15, 20, and 25 min) on the protein degradation and non-volatile flavor substances of swimming crab (Portunus trituberculatus), the moisture content, total nitrogen (TN), non-protein nitrogen (NPN), free amino acids (FAAs), flavor nucleotides, electronic tongue analysis, and sensory evaluation were determined. The results showed that the contents of NPN and total FAAs were the highest after crabs steamed for 10 min. Meanwhile, the AMP (adenosine monophosphate) content reached the maximum value (332.83 mg/100 g) and the taste active value (TAV) reached 6.67, which indicated that AMP contributes the most to the taste of steamed crab at 10 min. The electronic tongue distinguished the taste difference well, and the sensory score was the highest at 15 min. Combined with equivalent umami concentration (EUC) and TAV value, swimming crab (weight = 200 ± 20 g) steamed for 10-15 min tasted best.

Understanding the Development of Heterocyclic Aromatic Amines in Fried Bacon and in the Remaining Oil after Pan-Frying in Five Different Vegetable Oils.

The physicochemical properties of five vegetable oils (peanut, corn, rapeseed, sunflower seed, and soybean) and their impact on the development of heterocyclic aromatic amines (HAAs) in pan-fried bacon and in the remaining oil were investigated. Corn oil led to the lowest total free amino acids (FAAs) contents and glucose content of fried bacon (p < 0.05) and rapeseed oil led to the lowest creatine content of fried bacon (p < 0.05). Bacon fried in corn oil had the highest HAA contents (p < 0.05). The total HAA contents of the oils after frying were lowest in rapeseed and soybean oils (p < 0.05). The type of vegetable oil used affected the color of the fried bacon but not the flavor and taste (p < 0.05). To reduce the HAA concentrations of fried bacon, the type of vegetable oil should be considered.

Effect of different ripening conditions on amino acids and biogenic amines evolution in Sjenički sudžuk

The aim of this study was to determine the influence of alternative ripening (thermo-hygrometric) conditions in the summer production season (batch S) on changes in free amino acids (FAA) and biogenic amines (BA) content in dry-fermented sausage Sjenički sudžuk, compared to traditional production during winter (batch W) in small/micro processing plant. Consequently to important proteolytic changes, both in batch W and especially in batch S, the concentration of total FAA increased (P < 0.05) over time, being 600 mg/100 g dm and 844 mg/100 g dm, respectively. By the end of ripening, the total concentration of six analyzed BA reached 399 mg/kg and even 2468 mg/kg in batches W and S, respectively. Predominant amines in batch W were putrescine and tyramine, and in batch S were cadaverine and putrescine. The concentration of these amines increased significantly (P < 0.05) throughout ripening within each of the observed periods of the year. Regarding histamine, the registered concentration was very low in samples of batch W (9.69 mg/kg), while the sausages of batch S were characterized by a much higher concentration of this harmful compound (333 mg/kg). In respect of this finding, the summertime production of Sjenički sudžuk in small/micro processing plants should be avoided until necessary manufacturing process modifications are implemented.