Flavor differences of soybean and defatted soybean fermented soy sauce and its correlation with the enzyme profiles of the kojis.

BACKGROUND: Soybeans and defatted soybeans, commonly used as protein ingredients, have different flavors of their fermented soy sauce. Clarifying the differences between the two soy sauces, as well as the formation mechanism, is an important prerequisite for improving the flavor of defatted soybean soy sauce. To this goal, the aroma characteristics of two soy sauces and their volatile profiles were compared by sensory evaluation and gas chromatography-mass spectrometry, and eight enzyme activities and volatile profiles of matured koji were determined. RESULTS: Sensory results showed that the acids, fruity and cooked potato-like attributes were higher in whole soybean fermented soy sauce, whereas defatted soybean soy sauce exhibited higher smoky and malty attributes, closely related to the contents of aroma-active compounds in soy sauce, such as isobutyl acetate, 2/3-methylbutanal, acetic acid and 2/3-methylbutanoic acid. The content of most volatiles in the matured kojis showed a consistent trend with that of soy sauce: alcohols, acids, furan(one)s and ketones. Interestingly, acid protease and cellulase activities were 3.3 and 1.6 times higher in the whole soybean koji than in defatted soybean koji, respectively, whereas neutral protease, aminopeptidase, glucoamylase and ß-glucosidase were approximately 2.0 times higher in defatted soybean koji. CONCLUSION: In summary, the flavor differences between soybean and defatted soybean fermented soy sauce were not only caused by the differences in the content of flavor precursors in the materials, but also closely related to the differences in the enzymatic profiles accumulated during the koji-making process. © 2022 Society of Chemical Industry.

A comparison study on polysaccharides extracted from Fructus Mori using different methods: structural characterization and glucose entrapment.

In this study, the structure characteristics and the hypoglycemic and antioxidant activities of mulberry fruit polysaccharides obtained by the commonly used hot water (MFPh)-, ultrasonic (MFPu)-, acid (MFPc)- and alkali (MFPa)-assisted extraction methods were investigated. NMR analysis indicated that the four polysaccharides had similar glycosidic linkage patterns. Scanning electron microscopy analyses showed that the surface morphology of the polysaccharides was greatly affected by the extraction methods. The results of the bioactivity assays indicated that MFPh exhibited stronger antioxidant and α-amylase inhibitory activities than the other polysaccharides. Moreover, all the polysaccharides showed good α-glucosidase inhibitory activities except for MFPu with the lowest molecular weight. These results suggested that acid, alkali, and ultrasonic-assisted extractions have different effects on the degradation of polysaccharides without changing the main structure compared with hot water extraction. In addition, the molecular weight of polysaccharides plays a key role in the bioactivity of the mulberry fruit polysaccharides.

Characterization of a novel alkaline Arxula adeninivorans urate oxidase expressed in Escherichia coli and its application in reducing uric acid content of food.

This study reported a novel highly active alkaline urate oxidase (UOX) and demonstrated its application in reducing uric acid content of food under alkaline conditions. The UOX gene was cloned from Arxula adeninivorans NBRC 10858, and its N-terminally his6-tagged form (rUOX) was overexpressed in Escherichia coli. The rUOX displayed maximal activity at 40 °C and pH 10, kept more than 90% initial activity under alkaline conditions (pH 9-11) and more than 80% at temperatures below 55 °C. The apparent Km, turnover number (kcat) and catalytic efficiency (kcat/Km) values for the substrate uric acid were respective 29.15 µM, 151.16 s-1 and 5.19 s-1. µM-1, which are improvements over previously reported UOXs. The rUOX efficiently reduced uric acid and purine contents in beer, beef and yeast extract at pH 10, indicating a promising application in food with low purine and uric acid contents to prevent hyperuricemia and gout.

Effects of combined high pressure and enzymatic treatments on physicochemical and antioxidant properties of peanut proteins.

Isolated peanut protein (PPI) dispersions were pretreated by high pressure at 100, 300, and 500 MPa prior to enzymatic hydrolysis with alkaline protease (Alcalase). The degree of hydrolysis (DH) was determined by the pH-stat method, the hydrolysates profiles were analyzed by high-performance liquid chromatography (HPLC), the molecular weight distribution (MWD) was analyzed by gel filtration chromatogram (GFC), and content of SH/S-S and antioxidant activity of hydrolysates were evaluated. Results showed that HP pretreatment improved effectively the enzymatic hydrolysis of PPI, with an effective sequence of 300 > 100 > 500 MPa. However, no significant differences were observed in the peak pattern of HPLC profiles, but the peak times were earlier in HPLC profiles of the HP-treated protein. GFC analysis showed that more peptide fractions with low molecular weight appeared in the hydrolysates of the HP-treated PPI with increasing pressure. Moreover, the level of free SH of hydrolysates of the HP-treated PPI was relatively higher than non-HP-treated PPI. The hydrolysates of the HP-treated PPI exerted higher antioxidant activity (reducing power and DPPH radical scavenging) than the hydrolysates of non-HP-treated PPI. The results indicated that high pressure treatment affected the enzymatic hydrolysis of peanut protein and some protein structure properties and improved antioxidant activity of PPI hydrolysates.

Anti-inflammatory Mechanism Involved in 4-Ethylguaiacol-Mediated Inhibition of LPS-Induced Inflammation in THP-1 Cells.

4-Ethylguaiacol, a common aroma compound of baijiu (a traditional Chinese alcoholic beverage), was assessed for its potential anti-inflammatory effects in an LPS-induced THP-1 cell model. To characterize the effect of 4-ethylguaiacol on the LPS-induced inflammatory response, the mRNA and protein expression of the TLR4-MAPKs-NF-κB-IκBα-AP-1, Nrf2-HO-1, and AMPK-SIRT1 pathways were monitored by ELISA, real-time PCR, and Western blotting. On the basis of the result, 4-ethylguaiacol exerted anti-inflammatory effects at doses of 10, 100, and 500 µM (the concentration of 4-ethylguaiacol in gujinggong baijiu is in the range of 1044 ± 44 to 1661 ± 63 µg/L) and significantly mitigated LPS-induced inflammation via activation of the Nrf2-HO-1 and AMPK-SIRT1 pathways and inhibition of NF-κB and AP-1 activation, thereby markedly inhibiting the activation of inflammasomes and down-regulating the production of inflammatory cytokines. These results indicated that 4-ethylguaiacol could reverse LPS-induced inflammatory responses and is a natural, potent anti-inflammatory component in baijiu.

Treatments of tilapia (Oreochromis niloticus) using nitric oxide for quality improvement: Establishing a potential method for large-scale processing of farmed fish.

BACKGROUND: To find a succedaneum of present methods for slaughtering tilapia, we have demonstrated the influence of nitric oxide (NO) (saturated NO solution) through euthanasia before slaughter on the animal welfare and muscle color of tilapia. The results suggested that NO euthanasia significantly improved the animal welfare and muscle color. Besides, the investigation of NO postmortem treatment on the muscle color and color stability of tilapia fillets suggested that NO postmortem treatment not only improved the muscle color and color stability but also prolonged the shelf-life of tilapia fillets during the refrigerated storage. OBJECTIVE: To further investigate the effect of NO euthanasia on the quality of tilapia fillets and to estimate the safety of NO treatments (NO euthanasia and NO postmortem treatment) for the application of NO treatments in industrial manufacturing of tilapia and possibly of other fish species. METHODS: NO euthanasia was adopted in this study following a simulated fish processing line. HbNO and MbNO values were measured to clarify the mechanism and process of NO euthanasia. The blood parameters, muscle pH, rigor index, drip loss and total volatile basic nitrogen (TVB-N) values were measured to evaluate the quality of the fillets obtained from NO euthanized tilapia. Besides, the nitrate (NO3-) levels in the muscles after the refrigerated storage were detected to estimate the food safety of both NO euthanasia and NO postmortem treatment. RESULTS: Fillets obtained from the tilapia euthanized by NO showed a later reduction of muscle pH, a later onset of rigor mortis postmortem and less drip loss during the refrigerated storage than control. NO euthanasia caused less TVB-N than control and prolonged the shelf life of tilapia fillets. Moreover, the NO3- levels in the muscles of both NO euthanasia and NO postmortem treatment after the refrigerated storage were below the maximum permitted limit. CONCLUSION: Both the NO euthanasia and NO postmortem treatment are suitable for improving the quality of tilapia fillets and reducing the food safety threats, which may be valuable for industrial manufacturing of tilapia and may be applicable for other fish species.

Cooling combined with hyperoxic CO2 anesthesia is effective in improving the air exposure duration of tilapia.

Tilapia were subjected to cooling (CO, a stepwise reduction in temperature from 30 °C to 15 °C), anesthesia (AN, anesthetized by hyperoxic carbon dioxide), air exposure (AE, exposed to air) and cold tolerance (CT, in 15 °C water) treatments, and the physiological responses were determined after the treatments. CO followed by AN treatment for tilapia could meet the criteria of an ideal anesthetic. Fish were deeply sedated within 69 s, completely anesthetized within 276 s and recovered within 308 s without any mortality. The stress responses induced by the CO&AN treatment were mild, whereas they were consistently increased in the AE treatment. Furthermore, the AE treatment caused tissue damage. The AE duration was significantly improved by CO&AN treatment, and the survival time of the CO&AE, AN&AE and CO&AN&AE treatments were 313 min, 351 min and 561 min, respectively, in the laboratory experiments, whereas the survival rate of the CO&AN&AE treatment group after 240-min air exposure was 95.2% in the pilot test. It appeared that cooling followed by hyperoxic CO2 anesthesia would be suitable for handling tilapia in a short-time air exposure procedure.

Enhanced butanol production from cassava with Clostridium acetobutylicum by genome shuffling.

To obtain strains exhibiting high levels of solvent tolerance and butanol production, wild type strains of Clostridium acetobutylicum butanol-producing strain GX01 and Lactobacillus mucosae butanol-tolerant strain M26 were subjected to mutagenesis combining N-methyl-N-nitro-N-nitrosoguanidine induction with genome shuffling. After four successive rounds of genome shuffling, the C. acetobutylicum shuffled strain GS4-3 showing greater levels of fermentation performances (such as secreting a higher level of amylase, improving the thermal stability, and possessing greater environmental robustness) compared to the wild type strains was isolated. As a result, after optimization of culture conditions, mutant GS4-3 produced 32.6 g/L of total solvent, 20.1 g/L of butanol production, and 0.35 g/L/h of butanol productivity, which were, respectively, increased by 23.5, 23.3, and 40.0 % than the wild-type strain GX01, in a 10 L bioreactor. The enhanced production of butanol and tolerance of solvent of mutant associated with GS4-3 make it promising for acetone/butanol/ethanol fermentation from cassava (Manihot esculenta).

Effects of koji-making with mixed strains on physicochemical and sensory properties of Chinese-type soy sauce.

BACKGROUND: Two kinds of soy sauces were prepared with Aspergillus oryzae koji (SSAO) and mixed koji (SSAOM, A. oryzae mouldstarter:Monascus purpureus mouldstarter = 1:2, w/w) respectively. The effects of mixed koji on the essential indices, oxygen radical absorption capacity, color indices, free amino acids and volatile compounds of soy sauce have been studied, followed by a sensory evaluation between SSAO and SSAOM. RESULTS: The contents of non-salt soluble solid, reducing sugar, total acid, total nitrogen and amino nitrogen in SSAOM increased by 21.50%, 9.88%, 15.35%, 5.98% and 41.43%, respectively, compared with the control SSAO, owing to the higher activities of acid protease and glucoamylase in the mixed koji. Moreover, SSAOM showed higher antioxidant activity, higher levels of free amino acids and much more attractive color. Meanwhile, flavor groups such as esters, aldehydes, pyrazines and sulfur-containing compounds in SSAOM were also improved. The contents of free amino acids and aroma compounds were consistent with the sensory evaluation. According to descriptive sensory analysis, SSAOM showed higher intensity for sweet and umami attributes; in addition, higher flowery, burnt, fruity and caramel-like attributes were perceived in SSAOM, while SSAO showed higher ethanolic and sour attributes. CONCLUSIONS: The investigated soy sauce prepared with mixed koji can be considered as an effective method to accelerate the fermentation process and improve the flavor of soy sauce.

Antioxidant and nitrite-scavenging capacities of phenolic compounds from sugarcane (Saccharum officinarum L.) tops.

Sugarcane tops were extracted with 50% ethanol and fractionated by petroleum ether, ethyl acetate (EtOAc), and n-butyl alcohol successively. Eight phenolic compounds in EtOAc extracts were purified through silica gel and Sephadex LH-20 column chromatographies, and then identified by nuclear magnetic resonance and electrospray ionization mass spectra. The results showed that eight phenolic compounds from EtOAc extracts were identified as caffeic acid, cis-p-hydroxycinnamic acid, quercetin, apigenin, albanin A, australone A, moracin M, and 5'-geranyl-5,7,2',4'-tetrahydroxyflavone. The antioxidant and nitrite-scavenging capacities of different solvent extracts correlated positively with their total phenolic (TP) contents. Amongst various extracts, EtOAc extracts possessed the highest TP content and presented the strongest oxygen radical absorbance capacity (ORAC), 1,1'-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity, 2,2'-azobis-3-ethylbenthiaazoline-6-sulfonic acid (ABTS) radical-scavenging capacity, ferric reducing antioxidant power (FRAP) and nitrite-scavenging capacity. Thus, sugarcane tops could be promoted as a source of natural antioxidant.

Investigation of the susceptibility of acid-deamidated wheat gluten to in vitro enzymatic hydrolysis using Raman spectra and free amino acid analysis.

BACKGROUND: The number and surface nature of amino acids (AAs) in substrate proteins available to hydrolytic enzymes are critical. Among them, the micro-environmental properties of specific AAs in substrates before hydrolysis would probably dominate the susceptibility of substrates to enzymatic hydrolysis. Fundamental knowledge concerning this regard is lacking. The objective of this work was to investigate the relationship between the exposure level of AAs in acid-deamidated wheat gluten and their susceptibilities to in vitro enzymatic hydrolysis by pancreatin through both high-performance liquid chromatography and Raman spectra. Wheat gluten deamidated with HCl (HDWG), citric acid (CDWG), succinic acid (SDWG) and acetic acid (ADWG) at the same degree of deamidation under the same heat treatment were chosen as the substrates. Substrate characterisations including degree of hydrolysis, surface hydrophobicity and structural characteristics before hydrolysis, together with analysis of free AAs of the corresponding hydrolysates during hydrolysis, were investigated. RESULTS: Hydrolysates from SDWG had the highest value for the degree of hydrolysis. The susceptibility of CDWG to pancreatin hydrolysis was the lowest, lower than native wheat gluten (CK) after the initial 36 h. Compared with free AAs, the mole increase profiles of CK, Arg production levelled off in HDWG after 12 h whereas it was inhibited in ADWG. For SDWG, Arg release was dramatically inhibited after 12 h and was replaced by Trp. Investigations using Raman spectra of the micro-environment of Cys, Trp, Tyr and His and the mole increase trend of them indicated that the exposure level of these amino acids in substrates was positively related to their susceptibilities to pancreatin hydrolysis especially after 24 h of hydrolysis. CONCLUSION: Deamidation by four acids has a distinct influence on the structural characteristics of wheat gluten substrates. Although the substrates were selected at the same level of deamidation by the same heat treatment, their resultant conformational differences significantly influenced the exposure level of amino acids for binding to enzymes and the susceptibility of substrates to in vitro enzymatic hydrolysis. Therefore, it had an influence on changing enzyme cutting sites of pancreatin. This information will provide a better understanding of specific behaviour of AAs in wheat gluten during enzymatic hydrolysis from a new perspective.

Application of targeted drug delivery system in Chinese medicine.

Targeted drug delivery system of traditional Chinese medicine (TCM) refers to those using different carriers to make the effective parts or monomer extracted from TCM or natural medicine into agents which can directly concentrate on the target site. This system is an ideal delivery approach and has became a hot spot in the field of TCM pharmaceutical research since it can improve the pharmacological effects and reduce the adverse reactions. This paper reviews literatures on TCM targeted agents which were published in the past 10 years. In accordance with the different carriers, four types of agents, liposome, nanoparticle, microsphere, and emulsion are analyzed. Liposomes were studied most profoundly and a variety of new types of liposomes was developed on the basis of the traditional liposomes. Using natural or synthetic polymer materials to carry drugs, nanoparticles and microspheres can promote the drug through the blood-brain barrier and enhance its bioavailability. Emulsion has lymphatic affinity and the drug is coated in the internal phase, which can protect the drugs from hydrolysis. All these delivery agents are proved to be effective ways to improve the clinical efficacy of drugs, and each is discussed in detail with examples. At present, TCM targeted agents are still in the exploratory stage and many problems need to be solved. Especially, it is a huge challenge to research the targeted delivery systems for the effective parts of Chinese medicines and compound prescriptions, and the paper gives a particular discussion on this point. In the future, more attention should be paid to the research on the particle agents of TCM effective parts, and the development of new carrier materials in order to enhance the overall quality of TCM targeted agents.

Characterization of hydrolysates derived from enzymatic hydrolysis of wheat gluten.

The aim of this study is to investigate the characteristics of wheat gluten hydrolysates. Enzymatic hydrolysis was performed using a papain (food-grade enzyme) in the present study. The gluten proteins were hydrolyzed for 8 h. During enzymatic hydrolysis, average peptide chain length in the hydrolysate decreased rapidly. Increasing proteolysis resulted in the increase in the contents of the soluble forms of nitrogen. However, the content of peptide nitrogen increased within the 1st 6 h, and then began to decrease. The percentage of the released peptides with molecular weight (MW) of over 15 kD decreased with extending enzymatic hydrolysis, while those with MW below 5 kD increased significantly (P < 0.05). The peptides with MW 10 to 15 kD and those having the MW 5 to 10 kD had different changes. The polymeric glutenin and monomeric gliadin in gluten complex showed different behavior after enzymatic hydrolysis. The monomeric protein (gliadin) and soluble glutenin were prone to enzymatic hydrolysis, while insoluble glutenin was resistance to enzymatic hydrolysis.