Automatic Amino Acid Analyzer Research Articles

Effect of Different Cooking Methods on the Aroma and Taste of Chicken Broth.

A single combi oven, known for its versatility, is an excellent choice for a variety of chicken soup preparations. However, the impact of universal steam ovens on the flavor quality of chicken soup remains unclear. This study aimed to explore the impact of different cooking methods on the aroma and taste of chicken soup. Three cooking methods with various stewing times were compared: ceramic pot (CP), electric pressure cooker (EPC), and combi oven (CO). Analyses were conducted using electron-nose, electron-tongue, gas chromatography-ion mobility spectrometry (GC-IMS), automatic amino acid analysis, and chemometric methods. A total of 14 amino acids, including significant umami contributors, were identified. The taste components of CP and CO chicken soups were relatively similar. In total, 39 volatile aroma compounds, predominantly aldehydes, ketones, and alcohols, were identified. Aldehydes were the most abundant compounds, and 23 key aroma compounds were identified. Pearson's correlation analyses revealed distinct correlations between various amino acids (e.g., glutamic acid and serine) and specific volatile compounds. The aroma compounds from the CP and CO samples showed similarities. The results of this study provide a reference for the application of one-touch cooking of chicken soup in versatile steam ovens.

Characterization of Amino Acid Composition, Nutritional Value, and Taste of Fruits from Different Actinidia arguta Resources

The nutritional value and flavor and texture characteristics of fruits from different Actinidia argute resources were scientifically evaluated and compared. Using 35 A. arguta fruits as materials, the amino acid composition and content were determined by an automatic amino acid analyzer, and differentiation analysis, amino acid nutritional value evaluation, TAV flavor analysis, correlation analysis, PCA comprehensive evaluation, and cluster analysis were conducted to clarify the diversity of A. arguta resources in terms of amino acid content, composition, and flavor characteristics. Analysis of differential results showed that the A. arguta resource fruits contained 17 amino acids with a total amino acid content of 384.20∼2590.56 mg/100 g. The results of the nutritional value evaluation showed that the Leu of the fruits of the A. arguta resources all conformed to the ideal model proposed by FAO/WHO, and the Leu content of all the resources exceeded the human body’s needs, and it was also found that the first limiting amino acid of the Actinidia argute resources was Ile and the second limiting amino acid was Lys. TAV of the flavor-presenting amino acids was calculated to evaluate the flavor-presenting taste characteristics, and the amino acids that influenced the flavor of A. arguta fruit were Glu and Cys. PCA showed that the 2 principal components could better reflect the comprehensive information of amino acids in A. arguta, and the cumulative variance contribution rate was 87.88%, which could represent the main trend of amino acids in A. arguta. A comprehensive amino acid evaluation model was established, and the composite scores indicated that the top 5 excellent resources were S4, S10, S18, S25, and S30. Hierarchical cluster analysis classified the 35 A. arguta resources into 4 categories, which better reflected the differences in amino acid content and composition, nutritional value, and taste characteristics among A. arguta fruits from different collection sites.

Different characteristics of 40 kinds of free amino acids and 5-amino levulinic acid between wines and sakes (Japanese rice wines)

Based on a systemic analysis for the global burden of disease study from 1990 to 2016, the Global Burden of Diseases (GBD) 2016 Alcohol Collaborators reported that alcohol use was a leading risk factor for global disease burden and caused substantial health loss. However, alcoholic drink (wines and sakes) contains abundant nutrients, particularly fermentable amino acids derived from grapes and rice. Amino acid nutrition and metabolism is strongly associated with health and prevention against various diseases. The purpose of this study was to elucidate 40 kinds of free amino acid (FAA) profiles in wines and sakes. In addition, the present study also provided the contents of 5-aminolevulinic acid (5-ALA) involved in the vital functionality of mitochondria. FAAs were detected and analyzed by use of an automatic amino acid analyzer. Aromatic amino acid, branched chain amino acid and Fischer ratio were calculated for each beverage. Individual FAAs showed significant differences between wines and sakes. Sakes abundantly contained almost all FAAs whereas wines had just a little content in some FAAs. Sake were rich in arginine, glycine, alanine, valine, glutamic acid and leucine, while wines were remarkably rich in proline (Pro). Wines showed increased FAA levels in 6 kinds of variables (4-hydroxyproline, 3-methyl histidine, β-alanine, α-aminobutyric acid, Pro and α-aminoadipic acid). In functionally characteristic FAAs, both wines and sakes were considerably abundant in γ-aminobutyric acid and 5-ALA. The total amount of aromatic amino acid and branched chain amino acid were markedly higher in sakes than in wines. These results revealed that there were the apparent different characteristics in FAA profiles between wines and sakes. This difference resulted from fermentation process in wines (single fermentation) and sakes (parallel double fermentation). Forty kinds of FAA profiles are more useful in investigating characteristics of the taste of wines and sakes. In future, detailed FAA analysis has the potential to find functional nutrients such as 5-ALA, whereas other foods generally contain little amount of these FAAs.

Comparative studies on the chemical composition and pharmacological effects of vinegar-processed antler glue modified from Lei Gong Pao Zhi Lun and traditional water-processed antler glue

Ethnopharmacological relevanceAntler glue is a classic medicinal to enhance sexual function in traditional Chinese medicine (TCM), which was first recorded in Shen Nong Ben Cao Jing (Shennong′s Classic of the Materia Medica). Vinegar-processing is a classic method of processing traditional Chinese medicine. The method of preparing antler glue by boiling antlers in vinegar and then concentrating them is recorded in Lei Gong Pao Zhi Lun (Master Lei′s Discourse on Medicinal Processing). In modern times, the typical processing method of antler glue is water extraction and concentration. However, it is not clear whether there is a difference in the effect of these two processing methods on the chemical composition and pharmacological activity of antler glue. Aim of the studyThe Chinese Pharmacopoeia (2020) records that the processing method of antler glue is water extraction and concentration. But Lei Gong Pao Zhi Lun differs in Chinese Pharmacopoeia (2020), which records the processing method of vinegar extraction and concentration. The effect of the two processing methods on antler glue's chemical composition and pharmacological activity is unknown. So this study aimed to elucidate the difference between different processing methods on the chemical composition and the treatment effect on oligoasthenospermia of antler glue. Materials and methodsSo the automatic amino acid analyzer is used to determine the amino acid content of two different processing methods of antler glue. Proteomics was performed to detect the protein components of two different processing methods of antler glue and analyze them. Cyclophosphamide-induced mice models of oligoasthenospermia were used to study the different pharmacological effects of antler glue in two different processing methods. An automatic sperm analyzer observed the quantity and quality of sperm in mice epididymis. Serum sex hormone testosterone (T), luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels in mice were tested using the enzyme-linked immunosorbent assay (ELISA) kits. Hematoxylin-eosin (H&E) staining was used to analyze pathological alterations in mouse testicular tissue. The transcriptome has been used to reveal the potential mechanism of antler glue in treating oligoasthenospermia. Mitochondrial complex activity assay kits were used to assay the activity of mitochondrial respiratory chain complex I–V in mouse testicular tissue. Western blot was used to determine the expression of related proteins in mouse testicular tissue. ResultsVinegar-processing can increase the alanine, proline, and glycine content in antler glue, reduce the length of protein peptides in antler glue, and produce a variety of unique proteins. Vinegar-processed antler glue (VAG) increased sperm density, sperm survival, sperm viability, and serum sex hormone levels in oligozoospermic mice. It reversed testicular damage caused by cyclophosphamide, and the effects were differently superior to those of water-processed antler glue (WAG). In addition, transcriptomics and related experiments have shown that VAG can increase the expression of Ndufa2, Uqcr11, Cox6b1, and Atp5i genes and proteins in mouse testis, thus promoting adenosine diphosphate (ATP) synthesis by increasing the activity of mitochondrial respiratory chain complexes I, III, IV and V. By promoting the oxidative phosphorylation process to produce more ATP, VAG can achieve the therapeutic effect of oligoasthenospermia. ConclusionVinegar-processing method can increase the content of active ingredients in antler glue. VAG increases ATP levels in the testes by promoting the process of oxidative phosphorylation to treat oligozoospermia.

The Influence of the Lactation Period and the Type of Milk on the Content of Amino Acids and Minerals in Human Milk and Infant Formulas.

(1) Background: This study investigated the effect of the lactation period and the type of infant formula on the content of amino acids and selected minerals in an infant's food; (2) Methods: The study material consisted of breast milk (colostrum, n = 38; transitional milk, mature milk, n = 38) and three types of infant formulas (for first and follow-on feeding). Amino acid content was determined using an automatic amino acid analyzer, while minerals were determined by the atomic absorption spectrometry (AAS) technique; (3) Results: Breast milk and infant formulas contained a full range of essential amino acids. In most cases, the content of individual amino acids and minerals decreased with increasing lactation. In infant formulas, there were higher contents of phenylalanine, glutamic acid, proline, serine, and tyrosine in follow-on milk (p < 0.05). The EAA/TAA ratio in breast milk and infant formulas was similar, but the milk differed in their qualitative composition. Infant formulas contained levels of individual minerals that were several times higher-especially Mg, Ca, Mn, and Fe.; (4) Conclusions: Colostrum is more concentrated, and the level of amino acids and minerals is higher in it; as the milk matures, it decreases. In most cases, the content of individual amino acids and minerals is higher in infant formulas than in human milk, which is established through strict Codex Alimentarius procedures to ensure the proper development of infants.

Bone marrow mesenchymal stem cells response on collagen/hyaluronan/chondroitin scaffold enriched with gentamicin -loaded gelatin microparticles for skin tissue engineering.

The repair and functional reconstruction of large skin defects caused by burn remains an intractable clinical problem. Collagen type I (ColI) was extracted from carp scales and confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis ultraviolet adsorption spectra and automatic amino acid analyzer. Then the scaffolds containing the purified ColI, hyaluronic acid (HA) and chondroitin sulfate (CS) were constructed and examined. The results showed that the scaffold (ColI:CS:HA=9:1:1) had larger pore diameter, porosity, water absorption, degradation rate and tensile strength. gentamycin sulphate (GS) - gelatin microspheres (GMSs) were prepared by emulsion cross-linking method. The drug release study of the ColI-CS-HA-GS/GMSs scaffold with antibacterial property showed a prolonged, continuous, and sustained release of GS. The bone marrow mesenchymal stem cells (BMSCs) were extracted from rat and inoculated into the ColI-HA-CS-GS/GMSs scaffold. The results performed that the scaffold could accelerate proliferation of the BMSCs and wound healing.

Comparative Study on Nutritional Characteristics and Volatile Flavor Substances of Yak Milk in Different Regions of Gannan.

This study aimed to investigate the nutritional properties of yak milk in various areas of Gannan. The milk composition analyzer, automatic amino acid analyzer, and flavor analyzer were used to detect the conventional nutrients, amino acids, and volatile flavor substances of 249 yak milks in Meiren grassland, Xiahe grassland, and Maqu grassland (hereinafter referred to as Meiren yak, Xiahe yak, and Maqu yak) in the Gannan area. The results showed that the fat content of Meiren yak milk was significantly higher than that of Maqu yak and Xiahe yak (p < 0.05). The protein content of Meiren yak milk was significantly higher than that of Xiahe yak (p < 0.05), but not significantly different from that of Maqu yak (p > 0.05). The casein content in the milk of Maqu yak was significantly higher than that of Meiren yak and Xiahe yak (p < 0.05). There was no significant difference in the lactose content of yak milk in the three regions (p > 0.05). The content of glutamic acid in the milk of Meiren yak, Xiahe yak, and Maqu yak was noticeably high, which was 1.03 g/100 g, 1.07 g/100 g, and 1.10 g/100 g, respectively. The total amino acid (TAA) content was 4.78 g/100 g, 4.87 g/100 g, and 5.0 g/100 g, respectively. The ratios of essential amino acids (EAA) and total amino acids (TAA) in the milk of Meiren yak, Xiahe yak, and Maqu yak were 42.26%, 41.27%, and 41.39%, respectively, and the ratios of essential amino acids (EAA) and nonessential amino acids (NEAA) were 73.19%, 70.28%, and 70.61%, respectively. In the yak milk samples collected from three different regions, a total of 34 volatile flavor compounds were detected, including 10 aldehydes, five esters, six ketones, four alcohols, two acids, and seven others. The main flavor substances qualitatively obtained from Meiren yak milk were ethyl acetate, n-valeraldehyde, acetic acid, heptanal, and n-hexanal. Xiahe yak milk mainly contains ethyl acetate, isoamyl alcohol, n-valeraldehyde, heptanal, and ethyl butyrate. Maqu yak milk mainly contains ethyl acetate, n-valeraldehyde, isoamyl alcohol, heptanal, ethyl butyrate, and n-hexanal. Principal component analysis showed that the flavor difference between Xiahe yak and Maqu yak was small, while the flavor difference between Xiahe yak, Maqu yak, and Meiren yak was large. The findings of this research can serve as a foundation for the future advancement and application of yak milk.

Effects of simmering time, salt and sugar addition on the flavour and nutrient release of Morchella soup

AbstractThis study aimed to investigate the effect of different simmering times, salt and sugar addition on the quality of the Morchella soup. The change in the released contents of nutrients and flavour compounds in the Morchella soup within 120 min was studied. The automatic amino acid analyser, solid‐phase microextraction–gas chromatography–mass spectrometry, phenosulphuric acid method, acid–base neutralization principle and 1,1‐dipheny2‐picrylhydrazyl scavenging activity were used to determine the changes in free amino acids, volatile flavour compounds, total sugar, titratable acids and antioxidant activities in the Morchella soup respectively. The results showed that the amount of amino acids, volatile flavour compounds, titratable acid, antioxidant capacity and total sugar in the Morchella soup were significantly higher at 40‐min simmering time than at other simmering times. At 40‐min simmering time, the salt and sugar addition increased the amounts of umami amino acids (54.33%, 23.48%) and total amino acids (40.83%, 20.02%), organic acids (211.6%, 127.74%), sulphur‐containing compounds (130.40%, 237.20%), titratable acids (43.3%, 16.7%), and total sugar (23.8%, 16.7%) and antioxidant activity (87.5%, 23.8%) in the Morchella soup respectively. This study revealed the influence mechanism of simmering time, salt and sugar addition on the Morchella soup and provided a basis for further processing the Morchella soup.

Effects of polyphenols on the gel and digestive properties of Penaeus vannamei myosin after freezing.

Polyphenols could inhibit the freezing-induced denaturation of myosin, and affect its nutritional and functional properties, which have rarely been studied to date. Therefore, the effects of interactions between polyphenols and myosin after freezing on myosin gel and digestive properties were investigated using low field NMR, a texture analyzer, a dynamic rheometer, ultraviolet-visible spectra, scanning electron microscopy, LC-MS/MS, an automatic amino acid analyzer, etc. Hesperetin (HE), dihydroquercetin (DI), salidroside (SA), and mangiferin (MA) increased the water-holding capacity, non-flowable water content, gel strength, texture, storage modulus, and fractal dimensions of the myosin gel, while modifying its leading force. The results of scanning electron microscopy revealed that the surfaces of polyphenol groups were relatively smoother than those of the control group. Meanwhile, the four types of polyphenols under study significantly improved the gastric and gastrointestinal digestibility of myosin. Furthermore, they significantly increased the contents of essential, flavor, and total free amino acids, as well as the unique peptide numbers in myosin digestion products. This work provides reliable guidance for polyphenols to improve protein function and nutritional properties.

A Study of the Ameliorative Effect of Gryllus bimaculatus on Sarcopenia

Purpose: Currently, aging-related sarcopenia is considered a serious problem. However, few studies have addressed the treatment or prevention of sarcopenia using Gryllus bimaculatus . Therefore the present study was carried out to determine whether Gryllus bimaculatus has an ameliorative effect on sarcopenia and to study its applicability as a food for sarcopenia in the elderly or in patients with this condition.Methods: The contents of moisture, crude ash, crude protein, crude fat, carbohydrate and minerals were analyzed. The amino acid and fatty acid compositions were analyzed using an automatic amino acid analyzer and gas chromatography, respectively. Cell viability was measured using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Myostatin expression was investigated in C2C12 cells using a luciferase reporter assay after treatment with a Gryllus bimaculatus extract.Results: The Gryllus bimaculatus powder (GBP), protein extract of Gryllus bimaculatus (PEGB), Gryllus bimaculatus egg (GBE), and egg protein extract of Gryllus bimaculatus (EPGB) were high in essential amino acids, especially branched chain amino acids, and unsaturated fatty acids, and low in carbohydrates. Moreover, Gryllus bimaculatus appeared to have ameliorative effects on sarcopenia by suppressing the mRNA expression of myostatin in C2C12 cells.Conclusion: It is expected that Gryllus bimaculatus will be positive for the development of food materials or to prevent sarcopenia in the elderly or in patients with this condition.

Preparation and Characterization of Flavored Sauces from Chinese Mitten Crab Processing By-Products

To achieve high-value utilization of Chinese mitten crab processing by-products, different types of sauces were prepared using crab legs (CLs) and crab bodies (CBs). Two processing methods, enzymatic hydrolysis and enzymatic hydrolysis coupled with the Maillard reaction, were employed to prepare these sauces. An electronic nose (E-nose) and electronic tongue (E-tongue) were used to measure the changes in the taste and odor, an automatic amino acid analyzer was used to measure the amino acid content, and a headspace solid-phase microextraction GC/MS (HS-SPME-GC/MS) was used to analyze the volatile compounds, qualitatively and quantitatively. The results showed that the sour, bitter, and other disagreeable odors of the enzymatic hydrolysis solution (EHS) were reduced following the Maillard reaction; meanwhile, the umami and saltiness were considerably enhanced. The quantity of free acidic amino acids with an umami and sweet taste in the CL and CB sauces after enzymatic hydrolysis and the Maillard reaction was substantially higher than that in the homogenate (HO). The Maillard reaction solution (MRS) produced more volatile compounds than the HO and EHS, such as aldehydes, pyrazines, ketones, etc. These compounds not only impart a unique flavor but also have antioxidant capabilities, making them a prototype for the high-value utilization of crab processing by-products.

Amino acid profiles in the tissue and serum of patients with liver cancer.

Most patients with liver cancer were found late and lost the chance of surgery. Liquid biopsy can monitor the risk of tumor recurrence and metastasis, quickly evaluate the curative effect of tumor treatment, and is conducive to early screening and auxiliary diagnosis of high-risk groups. Amino acid (AA) profiling has been used to the diagnosis and the prognosis for cancers. However, little was known about the profiles of AA of liver cancer. In this study, we used tRNA in Cancer database to analyze the AA levels in liver cancer tissues. Blood samples of patients with liver cancer were collected and analyzed using the automatic AA analyzer. We found that valine, isoleucine, and leucine were decreased significantly both in the plasma and the tumor tissues of patients with liver cancer. However, upregulation of methionine was observed in tissues and plasma of patients with liver cancer. Interestingly, tyrosine, and phenylalanine were decreased in tumor tissue but increased in the plasma of patients with liver cancer. This is the first report provided an overview of AA profile in both plasma and tissue for patients with liver cancer. AA levels can be used as diagnostic and prognostic markers of patients with liver cancer.

The ion balance of Shotokuseki extract promotes filaggrin fragmentation and increases amino acid production and pyrrolidone carboxylic acid content in three-dimensional cultured human epidermis

Natural moisturizing factor (NMF) in the stratum corneum contributes to the retention of moisture there. The purpose of this study was to determine the penetration of ions in Shotokuseki extract (SE) into the three-dimensional cultured epidermis and the effect of NMF on the biosynthesis of amino acids and pyrrolidone carboxylic acid formation. Various ions, amino acids and pyrrolidone carboxylic acid were quantified by inductively coupled plasma mass spectrometry, fully automatic amino acid analyzer or high-performance liquid chromatography (HPLC) in three-dimensional cultured epidermis after application of SE. Gene expression levels of profilaggrin, calpain1, caspase14, and bleomycin hydrolase, which are involved in NMF production, were determined by reverse-transcription qPCR and bleomycin hydrolase activity was determined by aminopeptidase assay. The application of SE increased Na, K, Mg, Ca, Al, and Fe levels in three-dimensional cultured epidermis. The mRNA levels of the starting material of amino acid synthesis profilaggrin, and calpain1 and bleomycin hydrolase, which are involved in its fragmentation, increased. The activity of bleomycin hydrolase also increased. Furthermore, the levels of amino acids and pyrrolidone carboxylic acid increased in the three-dimensional cultured epidermis. This suggests that the ionic composition of SE may be involved in its moisturizing effect on the stratum corneum.Graphical

Effects of Pretreatment on the Volatile Composition, Amino Acid, and Fatty Acid Content of Oat Bran.

Pretreatment improves the edible quality of oat bran and prolongs the shelf life, whereas the effect of pretreatments (i.e., steaming(S-OB), microwaving(M-OB), and hot-air drying(HA-OB)) on the flavor characteristics of oat bran is unknown. This study identified volatile composition using HS-SPME/GC–MS and an electronic nose of oat bran. The amino acid compositions were determined by a High-Speed automatic amino acid analyzer and the fatty acids were determined by gas chromatography. The results showed that steaming and microwaving pretreatments enhanced the nutty notes of oat bran. Sixty-four volatile compounds in four oat brans were identified. OB exhibited higher aroma-active compounds, followed by S-OB, and M-OB, and the HA-OB had the lowest aroma-active compounds. Hexanal, nonanal, (E)-2-octenal,1-octen-3-ol, 2-ethylhexan-1-ol, and 2-pentylfuran were the key volatile compositions in oat bran. The aldehyde content decreased and the esters and ketones increased in steamed oat bran. Microwaving and hot air drying increased the aldehyde content and decreased the ester and alcohol content. Steamed oat bran had the lowest levels of total amino acids (33.54 g/100 g) and bitter taste amino acids (5.66 g/100 g). However, steaming caused a significant reduction in saturated fatty acid content (18.56%) and an increase in unsaturated fatty acid content (79.60%) of oat bran (p < 0.05). Hot air drying did not result in an improvement in aroma. The results indicated that steaming was an effective drying method to improve the flavor quality of oat bran.

THE AMINO ACID COMPOSITION OF MEAT PRODUCTS TREATED WITH PREPARATIONS OF MICROBIAL ORIGIN

Fermentation in the technology of dry-cured meat products helps to create products with high sensory characteristics and an extended shelf life. The purpose of this work was to study how bacterial and enzyme preparations affected the accumulation of free amino acids in dry-cured meat products.&#x0D; The work considers how the preparation Iprovit-Lakmik based on the cultures L. plantarum, L. rhamnosus, L. casei, and Micrococcus varians acts on the accumulation of free amino acids during the ripening of dry-cured sausages, and how the bacterial preparation Iprovit-MKS based on the cultures Lactoba plantarum, L. rhamnosus, and Staphylococcus simulans and the enzyme preparation Protolad acts on proteolysis during the ripening of dry-cured whole-muscle products from pork and beef. Fermentation was carried out in a climatic chamber at a temperature required by the technological process of accelerated ripening of fermented sausages, using bacterial and enzyme preparations. The starter culture Iprovit-Lakmik was added in the amount 0.05% to the volume of the sausage mince prepared in accordance with the formulation of the dry-cured sausage Zhytomyrska. The preparations Protolad and Iprovit-MKS were added at the stage of injecting the balyk (cured fillet) Darnitsky. Samples with no preparations added were the controls. The amino acid composition of proteins was determined by ion-exchange chromatography on an automatic amino acid analyser Biotronik LC2000. The total content of free cyclic amino acids was determined by the Hull method, and that of acyclic amino acids by the Gomez method, using colourimetry.&#x0D; It has been found that after fermentation, each product had its own characteristics of the qualitative and quantitative accumulation of free amino acids. Adding the preparation Iprovit-Lakmik to raw meat allowed directed biochemical transformations with the formation of a significant amount of free amino acids, which exceeded the control by 115.86 mg/100 g of dry matter. The enzyme preparation Protolad has a positive effect on the chemical and physicochemical characteristics of salted products from pork and beef. It has been proved that its use activates the breakdown of muscle tissue proteins and increases the pool of free amino acids. In the test samples from pork and beef, the content of free amino acids increased, respectively, by 1.7 times and 3.4 times, and that of non-essential amino acids by 1.4 times and 1.3 times respectively, compared with the control. In the samples with the bacterial preparation Iprovit-MKS, the total amount of amino acids increased significantly: by 32% for beef balyk and by 20% for pork balyk.

A rapid and efficient method of microwave-assisted extraction and hydrolysis and automatic amino acid analyzer determination of 17 amino acids from mulberry leaves

The microwave-assisted extraction and hydrolysis (MAEHM) and automatic amino acid analyzer (AAA) determination method (MAEHM-AAA) were developed and applied to extract and determine amino acids from mulberry leaves. The optimal extraction conditions were an extraction time of 10 min, an extraction temperature of 110 °C, a solid-to-liquid ratio of 1/50 and a microwave power of 400 W. The preponderance of MAEHM was demonstrated by comparison with the conventional heating acid hydrolysis method (CHAHM) using a first-order kinetics equation. The equilibrium concentrations (C∞) of the target compounds obtained by MAEHM were similar with those obtained by CHAHM. In addition, MAEHM had higher extraction reaction rate constants (k) than CHAHM, which suggests that the target compounds extracted by MAEHM could be much more effectively transferred from the plant matrix into the solvent than those by CHAHM. Compared with the preprocessing time of CHAHM (22 h), the preprocessing time of MAEHM was reduced to 15 min, which substantially reduced detection time. MAEHM-AAA provides a linear response over the concentration range of 0.1–500 nmol/mL with correlation coefficients above 0.99 in all cases. The low limits of detection (LODs) of this method were 0.025–3.75 nmol/mL, which shows its great sensitivity. In addition, the MAEHM was validated in terms of accuracy (the intra- and inter-day relative standard deviations were less than 6.62%), precision (80–120%) and stability (recovery was 90.38–121.66%). The MAEMH-AAA method was also successfully applied to quantify 17 target compounds in mulberry leaves.

THE EFFECT OF EXTRUSION PROCESSING ON THE PROTEIN COMPLEX OF FLAXSEED CAKE

As objects of research, we used the products of processing of oil flax seeds of the varieties August, Isilkulsky, Legur, Sokol and LM-98, grown on the experimental field of the State Agrarian University of the Northern Trans-Urals, Tyumen (2020). Flaxseed cake is obtained by "cold" pressing of oil by pressing, extruded flaxseed cake by passing the previously obtained cake through the extruder. The amino acid composition was determined by capillary electrophoresis on an automatic amino acid analyzer of the KAREL brand.&#x0D; 14 amino acids have been identified, of which 8 are irreplaceable. The total amount of essential amino acids is higher in the Sokol and August varieties (linseed cake – 18.19 and 10.48%, extruded linseed cake – 9.92 and 7.29%, respectively). Of the essential amino acids found in flaxseed cake, the highest content differs: lysine (from 2.86 to 1.08%), phenylalanine (from 3.82 to 1.22%), leucine and isoleucine (3.88–1.49%) , valine (4.00–1.13%), threonine (2.30–1.52%) and, accordingly, in extruded flaxseed cake: lysine (from 1.60 to 0.72 %), phenylalanine (from 1.98 up to 1.06 %), leucine and isoleucine (1.96–1.08%), valine (1.93–0.912%), threonine (1.77–0.81%). The results obtained allow us to recommend extruded flaxseed cake for expanding the range of bakery and flour confectionery products.

Determination of the chemical compounds of Shuchazao tea flowers at different developmental stages and in young shoots using 1H NMR-based metabolomics

The chemical compounds in tea leaves have been extensively explored in recent decades. However, the compounds in tea flowers have not been fully investigated. In present study, the main chemical compounds in tea flowers were identified at four developmental stages using non-targeted metabonomics based on proton nuclear magnetic resonance (1H NMR) and an automatic amino acid analyzer, and compared with those in young tea shoots. The results showed significant differences in catechins, sugars, organic acids and amino acids between tea flowers and young shoots. The concentrations of epigallocatechin gallate, epigallocatechin, epicatechin, and caffeine were significantly lower (p < 0.01) and sugar content significantly higher (p < 0.01) in flowers than in young shoots. Caffeine and β-glucose gradually decreased and sucrose constantly increased during flower development; α-glucose and fructose were most concentrated in the white bud and then decreased with flower development. Tea flowers contained more succinic acid, citric acid, and chlorogenic acid but less quinic acid and malic acid than young shoots. Both tea flowers and young tea shoots contained 20 common amino acids, including 7 essential ones. The concentration of amino acids was highest in the white bud (27.66 mg/g); young tea shoots contained significantly more L-theanine than tea flowers (p < 0.01). Our data indicate that the different stages of tea flowers have a set of characteristic chemical compounds and are potentially useful for functional foods.Graphical abstract

Flavour formation from hydrolysis of pork meat protein extract by the protease from Staphylococcus carnosus isolated from Harbin dry sausage

The impact of the protease from Staphylococcus carnosus on the structural characteristics, hydrolysis and flavour development of pork myofibrillar protein (MP) and sarcoplasmic protein (SP) were assessed. Hydrolysis altered the surface hydrophobicity and secondary structure of MP and SP, as measured by surface hydrophobicity, intrinsic fluorescence and Fourier transform infrared spectra. Atomic force microscopy and automated amino acid analysis revealed that the S. carnosus protease degraded the native proteins into low-molecular-weight hydrolysates with uniform distribution and free amino acids, especially glutamic and glycine acid. Moreover, the hydrolysis of MP and SP by the protease promoted the production of volatile compounds, such as aldehydes, alcohols, acids and esters. Molecular docking revealed the binding sites and the major interaction forces (hydrogen bonding) between actin and the protease. The molecular dynamics analysis showed that the binding process of the protease to actin induced a conformational change in actin. In summary, the potential application value of the S. carnosus protease in improving the flavour of Harbin dry sausage is suggested.

Comparison of the Nutritional and Taste Characteristics of 5 Edible Fungus Powders Based on the Composition of Hydrolyzed Amino Acids and Free Amino Acids

The nutritional characteristics and taste of some edible fungus powders were scientifically evaluated and compared. Five common edible fungus powders were used as test materials (Agrocybe chaxinggu edible fungus powder, Pleurotus citrinopileatus edible fungus powder, Flammulina velutipes edible fungus powder, Lentinus edodes edible fungus powder, and Hericium erinaceus edible fungus powder). The hydrolyzed amino acid and free amino acid content were measured by an automatic amino acid analyzer, and the ratios of hydrolyzed amino acid and free amino acid components and the taste characteristics of these eatables were systematically compared. The results showed that the total amount of hydrolyzed amino acids contained in the 5 edible fungus powders was between 2.583 and 14.656 g/100 g. The total amount of free amino acids contained in the 5 edible fungus powders was between 0.550 and 2.612 g/100 g. Comparative analysis of the mass fractions and composition of amino acids indicated that Pleurotus citrinopileatus edible fungus powder best met the ideal protein standard. The taste characteristics of protein were evaluated by calculating the taste active value (TAV) of taste-producing free amino acids. The most significant TAV values of the 5 edible fungus powders appeared in glutamic acid, and this amino acid is an umami amino acid. Principal component analysis (PCA) suggested that four principal components could reflect all the information on the free amino acids with a total cumulative variance contribution rate of 100%, and three principal components could reflect most of the information on the hydrolyzed amino acids with a total cumulative variance contribution rate of 99.143%, which could represent the main trends of free amino acids and hydrolyzed acids in edible fungus powder. The comprehensive evaluation model was established, and the comprehensive score indicated that Agrocybe chaxinggu edible fungus powder had the best comprehensive amino acid quality.