Saccharomyces cerevisiae var. diastaticus (S. diastaticus) is a major spoilage yeast in brewing. In the present research, the antifungal properties of nerol and the proteome response of S. diastaticus were studied. Results showed nerol can inhibit cell budding and delay yeast fermentation in a dose-depended manner. After 3 d of treatment with 0.25 mg.mL(-1) nerol, intracellular ROS levels increased 1.66-fold (P < 0.01), and the cells with damaged membrane increased to 23.2 %. Quantitative proteomic profiles utilizing a capillary-HPLC-MS/MS technology revealed that proteins involved in the metabolism of fermentable sugars were up-regulated in S. diastaticus cells treated with nerol, indicating nerol treatment altered the metabolite pattern of fermentable sugars. Proteins associated with the cell membrane biogenesis, heat shock proteins, amino acid biosynthesis, and glutathione metabolism were similarly up-regulated. These findings revealed the mechanism of nerol-induced yeast cell damage as well as the detoxification response of yeast cells.

Hops are abundant in natural bioactive compounds. In this work, nine prenylated bitter compounds from hop were evaluated for their inhibitory activity against α-glucosidase. As a result, four flavonoids and one phloroglucinol (lupulone, LP) outperformed acarbose in inhibiting α-glucosidase. Isoxanthohumol (IX) and LP with two types of structures were selected for inhibition mechanism studies by spectroscopic methods and molecular dynamics simulation (MD). Results showed that IX acted as noncompetitive inhibitor and bound to α-glucosidase in allosteric sites via hydrogen bonds, hydrophobic, van der Waals (vdW), and electrostatic force, whereas LP was uncompetitive inhibitor and bound to catalytic sites via hydrophobic and vdW interactions. Notably, the conformation around binding site of α-glucosidase formed stable α-helix and tightened after binding IX and LP, respectively, which helped to elucidate noncompetitive and uncompetitive inhibitory mechanisms. This work demonstrated that two types of prenylated bitter compounds are discrepant in their mechanisms of interaction with α-glucosidase.

In order to explore the quality changes of Alaska pollock fillet during salting, the Alaska pollock fillet were selected as raw materials and the drying conditions of Alaska pollock fillet were as follows: The amount of salt added was 100% (w/w), salting time was 15 days, and salting temperature was 10 ℃. The effects of different salting time on the quality of Alaska pollock fillets were studied with TBA, nitrite, fatty acid, free amino acid, tissue structure and volatile flavor compounds as indicators. The results showed that the TBA value of Alaska pollock fillet increased from 0.14 mg/kg to 0.26 mg/kg, the final content of nitrite which showed a trend of first increased and then decreased was 2.91 mg/kg. The total amount of saturated fatty acids in Alaska pollock fillet was slightly increased, the contents of pentacenoic acid and oleic acid in monounsaturated fatty acids significantly increased (P<0.05), and the contents of DHA and EPA in polyunsaturated fatty acids significantly decreased (P<0.05). The content of free amino acid showed a trend of first decreased and then increased. The macromolecular proteins which molecular weight was 100~245 kDa were gradually degraded, the content of actin which molecular weight was 48 kDa gradually increased and the proteins which molecular weight was less than 20 kDa were partially degraded. The cross section of muscle fibers of Alaska pollock fillet became irregular, muscle fibers contracted obviously, and the intercellular space first became larger and then smaller. The fishy components of Alaska pollock fillet decreased, and the contents of esters and alcohols increased. During the salting process of Alaska pollock fillets, the TBA value and nitrite of Alaska pollock fillet were within safe limits, the lipid oxidation was mainly polyunsaturated fatty acid oxidation, some macromolecular proteins were gradually degraded, the total amount of free amino acids increased in the middle and later stages of salting, the muscle fiber shrinked, the fishy smell decreased, and the overall flavor of fish meat was improved.

Xanthohumol (XN), as an abundant chalcone in hops, has received increasing attention due to its pharmacologic effects. However, poor solubility and bioaccessibility in aqueous solutions have limited its application. This work reported a novel carrier to improve the solubility and bioaccessibility of XN by using heat-stable, serpin-like protein Z (PZ) derived from barley malt. In this study, the solubility of XN was increased by 145-fold (vs. free XN in water) using 200 mu M PZ as the carrier. Fluorescence results demonstrated that XN interacted with PZ via static quenching process, with binding constant (K (a)) of 5.70 x 10 (4) L/mol at 298 K. PZ as a serine protease inhibitor exhibited excellent in vitro digestive stability that could inhibit trypsin with a low half inhibitory concentration (IC50) of 3.90 +/- 0.03 mg/L and showed only 26.54 +/- 0.70% degree of hydrolysis after gastrointestinal digestion. Furthermore, the retention ratio of XN was 50.28 +/- 1.80% after gastrointestinal digestion, which is 8-fold higher than XN alone, suggesting that PZ remarkably enhanced the bioaccessibility of XN. Molecular dynamics simulation analysis revealed that XN was bound within the hydrophobic pocket of PZ, near the Glu338 residue of PZ, whereas the external active loop of PZ was involved in binding with trypsin. This helped to elucidate the roles of PZ in improving the bioaccessibility of XN that PZ encapsulated XN in its hydrophobic cavity, without influencing its inhibition on trypsin. These findings suggest that PZ may be developed as carriers that protect XN or other hydrophobic bioactive molecules in the gastrointestinal tract.

BACKGROUND Bitter flavors and antioxidant activities are critical characteristics and indicators, respectively, of beer quality. To gain a better understanding of dry-hopped beer's bitterness, this work comprehensively evaluated the perceived bitterness intensity and bitterness attributes from aspects of beer aroma and non-volatile bitter compounds using sensory analysis under two conditions: (i) with and (ii) without nose clips. To quantify bitter and volatile compounds, the work conducted chromatographic analyses: high-performance liquid chromatography (HPLC), ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) and gas chromatography-mass spectrometry (GC-MS). Simultaneously, this work assessed the antioxidant activity of commercially dry-hopped beers. RESULTS First, dry-hopped beer in this study contained abundant non-volatile bitter compounds (hop bitter acids, polyphenols and flavonoids), and aroma was validated using HPLC, UPLC-MS and GC-MS methods. Moreover, the bitter-tasting perception test findings demonstrated that many dry-hopped beers had a higher bitterness intensity when evaluated without a nose clip, whereas this phenomenon was adverse in several ale beers. Additionally, the 'lingering' and 'harsh' characteristics were diminished when beer aroma was blocked out (with nose clip) for dry-hopped beer. Meanwhile, most dry-hopped beers had greater antioxidant activity than ale beers (P < 0.05). CONCLUSION This work revealed the bitterness complexity of dry-hopped beer; besides non-volatile bitter compounds, beer aroma had an impact on the perceived bitterness intensity and attributes, and dry-hopped beer had a relatively intense antioxidant capacity. This study facilitated the development of a detailed knowledge about the assessment of bitter-tasting perceptions in dry-hopped beers and provided a basis for the development of functional beer benefiting human health. (c) 2022 Society of Chemical Industry.

循环凝胶用水生产的鲢鱼丸经油炸后表面经常会产生孔洞和皱缩,影响鱼丸美观,降低鱼丸品质.为优化生产工艺、提高循环凝胶用水生产的油炸鱼丸品质,本研究基于工厂油炸鱼丸生产参数,模拟油炸鲢鱼鱼丸的生产过程,探究循环凝胶用水对鱼丸表面性状的影响.本研究对比了实验室模拟和工厂制作油炸鱼丸的循环凝胶用水pH、蛋白质含量和等电点指标,结合SDS-PAGE和Nano-HPLC-MS/MS技术对凝胶用水中的蛋白质组成进行鉴定.此外,通过向纯净水中添加蛋清和降低pH来验证不同蛋白含量和pH的凝胶用水对鱼丸表面性状的影响.结果表明,随着生产批次的增加,实验室模拟和工厂连续制作油炸鱼丸凝胶用水的pH都不断下降,蛋白质含量逐渐增加,等电点均维持在4.55～4.65,凝胶用水循环利用次数越多,生产出来的油炸鱼丸表面孔洞越多,皱缩越严重,且凝胶用水中沉积的蛋白质主要是卵白蛋白.增加凝胶用水中的蛋清含量、降低凝胶用水pH均会导致油炸鱼丸表面性状劣化,蛋清的添加会造成鱼丸更严重的表面性状劣化.油炸鱼丸表面性状劣化的主要原因是循环凝胶用水中蛋白质含量的增加和pH的降低,蛋白质主要是来自于鱼丸制作配料蛋清中的卵白蛋白.

Hyperphophorylation of tau protein is typical pathological features of Alzheimer's disease. Chicoric acid (CA) has been reported to inhibit formation of β amyloid peptide, it's hard to transport through blood brain barrier (BBB) and its role in inhibiting tau phosphorylation is unknown. In this study, we employed ferritin as a nanocage to encapsulate CA (Ft-CA), and stability, cell survival and BBB permeability of CA were improved by ferritin encapsulation, suggesting ferritin to be an effective vector for bioactive molecules. Meanwhile, both CA and Ft-CA were proved to inhibit tau phosphorylation in SH-SY5Y cells, and effects of Ft-CA are more obvious than CA. Roles of CA were proposed to regulate glucose metabolism by increasing GluT1 and promote glycosylation of tau protein. Meanwhile, CA was proved to inhibit phosphorylation of AMPK, which may further inhibit tau phosphorylation. These findings may provide a novel strategy to prevent neurodegenerative diseases by using dietary polyphenols.

Humulus lupulus L. is an essential source of aroma compounds, hop bitter acids, and xanthohumol derivatives mainly exploited as flavourings in beer brewing and with demonstrated potential for the treatment of certain diseases. To acquire a comprehensive understanding of the biosynthesis of these compounds, the primary enzymes involved in the three major pathways of hops' phytochemical composition are herein critically summarized. Hops' phytochemical components impart bitterness, aroma, and antioxidant activity to beers. The biosynthesis pathways have been extensively studied and enzymes play essential roles in the processes. Here, we introduced the enzymes involved in the biosynthesis of hop bitter acids, monoterpenes and xanthohumol derivatives, including the branched-chain aminotransferase (BCAT), branched-chain keto-acid dehydrogenase (BCKDH), carboxyl CoA ligase (CCL), valerophenone synthase (VPS), prenyltransferase (PT), 1-deoxyxylulose-5-phosphate synthase (DXS), 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (HDR), Geranyl diphosphate synthase (GPPS), monoterpene synthase enzymes (MTS), cinnamate 4-hydroxylase (C4H), chalcone synthase (CHS_H1), chalcone isomerase (CHI)-like proteins (CHIL), and O-methyltransferase (OMT1). Furthermore, research advancements of each enzyme in terms of reaction conditions, substrate recognition, enzyme structures, and use in engineered microbes are described in depth. Hence, an extensive review of the key enzymes involved in the phytochemical compounds of hops will provide fundamentals for their applications in beer production.

Monoterpenes are important flavor and fragrance compounds in food. In beer, the monoterpenes mainly come from hops added during boiling process. Biotransformations of monoterpene which occurred during fermentation conferred beer with various kinds of aroma profiles, which can be mainly attributed to the contribution of enzymes in yeast. However, there are few reports on the identification and characterization of these enzymes in yeast. Illustrating the structure and functions of key enzymes related to transformations will broaden their potential applications in beer or other foodstuffs. Monoterpenoids including terpene hydrocarbons (limonene, myrcene, and pinene) and terpene alcohol (linalool, geraniol, nerol, and citronellol) gave the beer flower-like or fruit-like aroma. The biotransformation of monoterpenes and monoterpene alcohols in bacteria and yeast, and potential enzymes related to the transformation of them are reviewed here. Enzymes primarily are dehydrogenases including linalool dehydrogenase/isomerase, geraniol/geranial dehydrogenase, nerol dehydrogenase and citronellol dehydrogenase. Most of them are substrate-specific or substrate-specific after modifications by biotechnology methods, and part of them have been expressed in E. coli, while the purification and catalytic rate is very low. Efforts should be made to acquire abundant enzymes, and to fabricate enzyme-expressing yeast, which can be further applied in beer fermentation system.highlightsMonoterpenoids contributed to the flavor of food, especially beer.Transformation of monoterpenoids occurred during fermentation.Various kinds of enzymes are involved in the transformation of monoterpenoids in bacteria, yeast, etc.Crystal structures of these enzymes have been partially resolved.Few enzymes are further applied in food system to obtain abundant flavor.

In order to solve the problems of long drying time and low drying sufficiency, the drying experiment was examined to verify the drying efficiency at different variable-temperature modes using the hop variety ‘Tuopu No.1’ obtained from Gansu Province A modified oven was taken as the baking media with a single-layer curing barn. The moisture content of the hop cones and the RH values of the hop layers at different drying temperatures were measured. Two optimal variable-temperature drying modes were selected, that was, in the drying process of hops, the temperature was set from 30 to 50 ℃(30~50 ℃) and from 30 to 60 ℃ and then down to 40 ℃(30~60~40 ℃). Baking with these two drying modes, the moisture content of hops could be reduced by 54.48% and 49.82% within 7 h, respectively. The drying efficiency was furtherly verified in the hop bakery of the workshop and the drying curves were analyzed. The linear models could give a good fit to the drying curves of the drying mode of 30~50 ℃(R2>0.96), while Weibull distribution models(β<1) fitted well to the drying mode of 30~60~40 ℃. It was proved that the two drying models belong to constant rate drying and falling rate drying, respectively. It was further verified that the drying efficiency was higher under the drying mode of 30~50 ℃. Hops drying at 30~60~40 ℃ had higher essential oil content, which was about 43% higher than that at 30~50 ℃. The above results indicated that the hops should be dried with a low temperature(30 ℃) in early stage and followed a high temperature(50 ℃) in late stage; In order to obtain more essential oil content in the final hops, the drying temperature could be reduced to some extent(40 ℃).

In this study, the evaluation of bitterness qualities and characteristic metabolite profiles in Krausen during beer fermentation were investigated using a UHPLC-Q/TOF-MS-based metabolomics approach and sensory evaluation analysis. Through sensory evaluation, Krausen was perceived as an extremely lingering bitterness character and exhibited impact on the bitter taste of beer and residue samples. Non-targeted metabolomics was employed to identify the potential bitter markers in Krausen through a differentiating approach across the metabolic profiles of Krausen, B1 (beer with Krausen removed), B2 (beer with Krausen retained), R1 (residue with Krausen removed), and R2 (residue with Krausen retained). Multivariate statistical analysis demonstrated that 41 of the screened key markers clustered towards the Krausen region were more or less hop bitter acid and its derivative. Subsequently, hop bitter acid and polyphenols were afterwards confirmed by quantification analysis. Both untargeted metabolomics and quantification results confirmed that isohumulones and humulinones contributed most towards the bitter profile of Krausen, while polyphenols may be not key compounds contributing to the bitter taste formation in Krausen. This study identified key bitter components of Krausen and may provided guidance for further research on taste quality of beer during fermentation.

单萜化合物是酒花和啤酒中香气化合物的重要组成部分,具有典型的酒花香气特征,在自然界中以游离态和糖苷结合态两种形式存在.本文重点阐述了酒花中单萜化合物的生物合成途径、控制其合成的关键酶和基因以及酒花中单萜醇化合物相互转化关键酶的研究进展.此外,本文还综述了酒花与啤酒中单萜化合物的变化及其影响因素,糖苷结合态单萜化合物的结构、含量及其分析方法,并对单萜化合物在啤酒中的研究前景进行展望.

Beijing Advanced Innovation Center for Foo Food Science & Nutritional Engineering, Ch No. 17 Qinghua East Road, Beijing 100083 Tel: +86-10-62736344 Key Laboratory of Functional Dairy, Co-co Beijing Municipality, College of Food Sci Agricultural University, Beijing, China Beijing Higher Institution Engineering Rese Food Science & Nutritional Engineering, Chi † Electronic supplementary informa 10.1039/c8ra05092a Cite this: RSC Adv., 2018, 8, 36034

RSV metabolites R3G and R4G protected HepG2 cell from insulin resistance by improving glucose uptake and glycogen synthesis, along with inhibiting ROS generation and modulating the RS-1/AMPK signaling pathway.

The production of smoked sturgeon fillets was studied and the production parameters smoking temperature, smoking time and drying time, ranging from 70–100℃, 15–60 min and 15–60 min, respectively, were optimized. Microbiological and physicochemical characteristics and flavor compounds of the product were analyzed. The results indicated that smoked sturgeon fillets produced by smoking at 85℃ for 22 min and drying for 22 min had the highest sensory score. Microbiological and physicochemical (moisture content, crude protein, crude fat, salt content, pH, total volatile basic nitrogen, benzopyrene and lfavor compounds) studies showed that the total viable count and coliform count of raw ifsh ifllets were reduced and no pathogenic bacteria were detected after smoking, accompanied by a decrease in moisture content and an increase in crude protein and crude fat contents. The smoked product contained only 0.24 μg/kg benzopyrene. In addition, the number of lfavor compounds identiifed in fresh ifsh was increased from 9 to 60 after smoking, especially the relative content of phenolic compounds was increased from 0.89% to 12.90% and one phenolic compound was detected in fresh ifsh versus nine phenolic compounds in smoked ifsh.

研究了液熏鲟鱼片的加工工艺及其对品质的影响,以期为液熏鲟鱼片产品开发提供理论指导.从烟熏液种类、烟熏液质量分数、液熏时间和干燥时间4个方面对烟熏鲟鱼片的工艺进行了优化.结果表明,山楂核烟熏香味料Ⅱ号,烟熏液质量分数5％,液熏3h,85℃干燥2h处理条件下液熏鲟鱼片具有浓郁而宜人的烟熏风味.进一步从微生物、含水率、粗蛋白、脂肪、盐分、有效酸度(pH值)、挥发性盐基氮(TVB-N)、苯并芘和挥发性风味成分方面评价鱼片液熏干燥后品质的变化,结果表明鲟鱼片总菌数由液熏前2×103 CFU/g减少为液熏后5×102 CFU/g,酚类物质相对含量由液熏前0.89％升高到液熏后8.62％.鲟鱼片液熏干燥后含水率减少而粗蛋白、粗脂肪含量升高,产品中未检出致病菌,苯并芘含量(质量比)仅为0.22 μg/kg.以上研究结果表明经本试验优化工艺制得的液熏鲟鱼片产品微生物及苯并芘含量符合相关标准,且风味良好,适宜进行大规模生产和推广.

<span id="ChDivSummary" name="ChDivSummary" class="abstract-text">为了解受群体感应信号肽介导的产细菌素乳杆菌作为发酵剂的潜力,以前期研究获得的1株Lactobacillus paraplantarum L-ZS9菌株为研究对象,L.plantarum L-Y9为对照,将L.paraplantarum L-ZS9+AIP（信号肽）、L.paraplantarum L-ZS9和L.plantarum L-Y9分别复配商用木糖葡萄球菌制备发酵香肠,测定不同发酵剂条件下各组香肠的微生物指标、理化指标和感官指标。结果表明:L-ZS9+AIP组效果最佳,与L-Y9组有显著差异（P&lt;0.05）,但与L-ZS9组差异并不明显（P&gt;0.05）。L-ZS9作为发酵剂能够更迅速启动发酵,较好地抑制肠杆菌的生长,及丙二醛（MDA）的增加,同时提高发酵香肠的感官品质。</span>

Chondroitin sulfates (CSs) were extracted from sturgeon skull and backbone, and their chemical composition, anticoagulant, anti-platelet and thrombolysis activities were evaluated. The average molecular weights of CS from sturgeon skull and backbone were 38.5kDa and 49.2kDa, respectively. Disaccharide analysis indicated that the sturgeon backbone CS was primarily composed of disaccharide monosulfated in position four of the GalNAc (37.8%) and disaccharide monosulfated in position six of the GalNAc (59.6%) while sturgeon skull CS was primarily composed of nonsulfated disaccharide (74.2%). Sturgeon backbone CS showed stronger antithrombotic effect than sturgeon skull CS. Sturgeon backbone CS could significantly prolong activated partial thromboplastin time (APTT) and thrombin time (TT), inhibited ADP-induced platelet aggregation and dissolved platelet plasma clots in vitro. The results suggested that sturgeon backbone CS can be explored as a functional food with antithrombotic function.

The aim of this research was to correlate the postmortem changes of sarcoplasmic proteins with instrumental color and various biochemical parameters relating to color attributes. Two-dimensional electrophoresis was used to investigate sarcoplasmic protein changes in cardiac muscle during refrigerated storage. Eleven differentially abundant protein spots were identified between storage time at day 1 and day 5 ( P < 0.05). The functional category of proteins consisted of metabolic enzymes, binding proteins, chaperone proteins, and antioxidant proteins. These proteins demonstrated positive correlation with a* -value (creatine kinase M-type and malate dehydrogenase), metmyoglobin-reducing activity (aconitate hydratase, creatine kinase, and thioredoxin-dependent peroxide reductase), tissue oxygen consumption rate (creatine kinase and malate dehydrogenase), and mitochondrial respiration control ratio (thioredoxin-dependent peroxide reductase and mitochondrial superoxide dismutase). The protein patterns were likely to have impact on postmortem metabolism, thereby protecting muscle against discoloration.

To increase the viable bacteria count of freeze-dried powder of staphylococcus,and to further prepare high quality meat starter powder of staphylococcus.Staphylococcus sciuri SL4obtained in previous study was taken as object due to its excellent fermentation capacity to optimize its cell collection conditions,cryoprotectant formula and initial cell concentration.The results showed that the optimal centrifuge speed and time were 6 000r/min and 10min, the cryoprotectant formulation consisted of 100g/L nonfat milk powder,23.56g/L glycerin,50g/L mannitol and 51.68g/L trehalose,the initial cell concentration was 109 CFU/mL.The survival rate of Staphylococcus sciuri SL4after vacuum freeze-drying could reach 95% under the optimized conditions.