麻竹笋腌制加工过程中风味物质的变化

为了研究麻竹笋腌制加工过程中风味物质的变化,以麻竹笋为原料,对其腌制过程中的挥发性成分、有机酸及氨基酸的含量变化进行分析。结果表明,在63 d的腌制过程中共检测到74种挥发性风味成分、8种有机酸及17种氨基酸。其中,苯酚类、酮类和烷烃类的相对含量随腌制时间的延长逐渐增加,醛类、烯烃类和其他类物质的相对含量则逐渐下降,醇类和酯类的相对含量先升高后降低。相对含量较高的挥发性成分有4-甲基苯酚、2-戊基呋喃、己醛、4-羟基苯甲醛、芳樟醇等。乳酸、乙酸和丙酸在腌制后含量升高,柠檬酸等其余5种有机酸在腌制后含量显著下降,大部分氨基酸在腌制后含量都有显著降低。该结果将为麻竹笋腌制过程中风味品质的评价和控制提供理论依据。     

Monitoring of the bacterial communities of bamboo shoots (Dendrocalamus latiflorus) during pickling process

The diversity and dynamics of the dominant bacterial communities arising during the pickling process of bamboo shoots (Dendrocalamus latiflorus) were investigated by nested polymerase chain reaction denaturing gradient gel electrophoresis combined with quantitative real‐time polymerase chain reaction. Results showed only several kinds of halophilic bacteria during early sampling time (0?3 days). After pickling for 7 days, Lactococcus lactis significantly increased (P < 0.05, quantities were 6.39 × 10⁵ copies μL^?1) and became the first dominant bacterium. After pickling for 14 days, Weissella sp. bands appeared and quickly became dominant on the 21st day (4.07 × 10⁶ copies μL^?1). As maturation progressed, Lc. lactis decreased in intensity whereas Weissella sp. increased in intensity. Finally, the quantities of Weissella sp. (2.50 × 10⁷ copies μL^?1) became higher than those of Lc. lactis (1.43 × 10⁷ copies μL^?1) after pickling for 56 days. The pickling process was initiated by Lc. lactis, followed by Lc. lactis and Weissella sp., and was finally succeeded by Weissella sp.     

基于Illumina MiSeq 高通量测序技术分析广西无盐发酵酸笋中细菌多样性

以10年老酸水泡制酸笋样品（BSFAF）、发酵6个月块状酸笋（MBSF）和丝状酸笋样品（FBSF）为研究对象,应用Illumina MiSeq高通量测序技术并通过生物信息统计与分析,探索广西无盐发酵酸笋样品中细菌菌群结构及多样性。结果表明：3组酸笋样品共得到148 656个有效的序列数（Tags）,聚类后总共得到1 116个分类操作单元(OTUs）。根据物种注释结果,在3组酸笋样品中共注释到12个门、23个纲、37个目、98个科和190个属。在门分类水平上,3组样品中厚壁菌门（Firmicutes）占绝对优势,其次是变形杆菌门（Proteobacteria）和放线菌门（Actinobacteria）;在属分类水平上,乳杆菌属（Lactobacillus）、乳球菌属（Lactococcus）和魏斯氏菌属（Weissella）是3组样品中的优势菌属。其中,丝状酸笋（FBSF）组的香农（Shannon）、辛普森（Simpson）及ACE指数均显著高于其他两组,且乳杆菌属（Lactobacillus）、乳球菌属（Lactococcus）和魏斯氏菌属（Weissella）的平均相对丰度总和最高,可达99.8%。因此,以泉水泡制发酵丝状竹笋生产酸笋可能更佳。     

Effects of genetic variability,parts and seasons on the sterol content and composition in bamboo shoots

Bamboo shoots are regarded as potential sources of sterols. The effects of genetic variability, parts and harvest seasons on the sterol content and composition in the bamboo shoots have been determined using a novel ultra-performance liquid chromatographic atmospheric pressure chemical ionisation mass spectrometer method. The results showed that the representative sterols in bamboo shoots were β-sitosterol, campesterol, stigmasterol, ergosterol, cholesterol and stigmastanol; exception stigmastanol, the significant differences were observed in the sterol content of different species (112.4–279.6 mg/100 g dry wt), different harvest seasons (195.3–279.6 mg/100 g dry wt) and different parts (253.6–321.8 mg/100 g dry wt); the sterol composition was similar in different species and different harvest seasons, however, it was significantly different between shoot bodies and shoot shell. The genetic variability, parts and harvest seasons could significantly affect the sterol composition in the bamboo shoots. The spring shoot shell of Phyllostachys pubescens contained the highest sterol content (321.8 mg/100 g dry wt).     

Effect of heat treatment on lignification of postharvest bamboo shoots (Phyllostachys praecox f. prevernalis.)

In order to evaluate the effects of heat treatment on the quality of postharvest bamboo shoots, the firmness, disease incidence, respiration and ethylene production, ACC synthase (ACS) and ACC oxidase (ACO) activities, lignin and cellulose contents, and the activities of phenylalanine ammonia-lyase (PAL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase (POD) were examined during storage at 20 °C after heat treatment at 45 °C for 5 h. Heat treatment inhibited disease incidence and respiration, retarded ethylene production, and decreased ACS and ACO activities in bamboo shoots. Furthermore, heat treatment significantly delayed the rise in the activities of PAL, CAD and POD, which were associated with the inhibition of the synthesis of lignin and the delayed tissue lignification. These findings suggest that heat treatment could be a potential tool to delay lignification and decrease disease incidence in bamboo shoots during storage at 20 °C.     

Accumulation of lignin and involvement of enzymes in bamboo shoot during storage

Fresh bamboo (Phyllostachys praecox f. prevernalis.) shoots were harvested, and the changes of firmness, electrical conductivity (EC), respiration rate, ethylene production, total sugars (TS), reducing sugars (RS), lignin and cellulose content and the activity of phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase POD were investigated during storage at 2 or 20°C for 30 or 12 days, respectively. EC increased quickly, with a more rapid rate at higher temperature, but it increased sharply after 24 days at 2°C. Respiration rate increased slowly at 20°C, while at low temperature (2°C) respiration rate and ethylene production significantly decreased. There was a quickly decrease in TS content at 20°C. Shoot firmness, lignin and cellulose increased and accelerated by higher storage temperature during storage at 2 or 20°C. Shoots firmness showed a positive correlation with accumulation of lignin and cellulose in the flesh. Among the enzymes associated with lignin synthesis, PAL and CAD activity showed a persistent rise over the whole 12 days, while POD activity increased rapidly within 6 days during storage at 20°C, followed by a slowly decrease. Accumulation of lignin in flesh tissue was also positively correlated to activity of PAL, CAD and POD. Our results suggest that the increase in firmness of bamboo shoots during storage is a consequence of tissue lignification, a process associated with increases in PAL, CAD and POD activity.     

Characterisation of volatile compounds in Maotai flavour liquor during fermentation and distillation

Volatile constituents in raw liquor and zaopei during fermentation and distillation were investigated by gas chromatography. Zaopei (steamed grains mixed with Daqu [FG1], stacking fermented grains [FG2], anaerobic fermented grains [FG3] and steamed grains [FG4]) presented changes in physicochemical properties. In all, 72 volatile compounds were identified in zaopei and raw liquor with similarity across 12 zaopei preparations. Principal component analysis and partial least squares discriminant analysis differentiated FG3 from other samples based on content of aroma compounds. FG3 had the highest level of aroma compounds, which increased from the fourth to sixth batches, and was characterised by the presence of 1, 2‐propanediol, acetic acid and linoleic acid, while the others were portrayed by phenylpropionate, ethyl laurate and 4‐ethyl guaiacol. The volatile compounds of raw liquor were dominated by ethyl acetate and ethyl lactate. Correlation analysis illustrated a lack of correlation of volatile compound content between the raw liquors and the zaopei distillation variants. © 2019 The Institute of Brewing & Distilling     

Quality and shelf life evaluation of pork nuggets incorporated with fermented bamboo shoot (Bambusa polymorpha) mince

Pork nuggets were processed by incorporating fermented bamboo shoot mince and their physico-chemical, microbiological and sensory characteristics were evaluated during 35 day storage at refrigeration temperature (4 ± 1 °C). Addition of fermented bamboo shoot significantly affects the pH, moisture, protein, fat, fiber, instrumental color values and texture profiles of nuggets, especially at 6% and 8% addition levels. Nuggets with 6% and 8% FBSM had significantly lower TBARS values at the end of the storage period (i.e. 0.39 and 0.33 mg malonaldehyde/kg respectively) compared to the control (0.84 mg malonaldehyde/kg). Bamboo shoot addition significantly improved the microbial and sensory qualities of the pork nuggets. Incorporation of fermented bamboo shoot at 8% level increased the shelf life of pork nuggets by at least two weeks i.e. from 21 days to 35 days at 4 ± 1 °C compared to the control.     

Disappearance of Maillard reaction products during ensilage and rumen fermentation in vitro

The disappearance of Maillard reaction products (MRPs) during ensilage and rumen fermentation was studied. MRPs were prepared by heating mixtures of D ‐glucose and glycine (GG) or D ‐xylose and glycine (XG); lyophilised powder (MW > 1000) was subjected to anaerobic incubation for 24 h with lucerne juice or buffered rumen fluid. Changes in MRPs were assessed by comparing gel filtration profiles before and after incubation, and the proportion of disappeared MRPs was calculated based on the area under the curve. A portion of MRPs, particularly high‐MW fractions, disappeared when incubated with lucerne juice, and the extent was greater (P < 0.01) in XG than in GG. The disappearance of GG was increased (P < 0.01) when ensilage was fortified with added glucose, while that of XG was unaffected with or without the fermentable substrate. Rumen fermentation had little impact on GG and XG, whereas a portion of MRPs disappeared when microbial activity was enhanced by adding lucerne hay to the media. Volatile fatty acid production was unaffected by MRPs in either ensilage or rumen fermentation. These results suggest that the effect on MRPs of anaerobic fermentation may be different between ensilage and rumen digestion. Significant amounts of MRPs would enter the intestine when ruminants are fed hay‐based diets rather than silage‐based diets. © 2000 Society of Chemical Industry     

基于核磁共振的代谢组学技术在肉品科学中的应用

核磁共振(nuclear magnetic resonance,NMR)波谱分析利用具有自旋性质的原子核在感应磁场中的能级跃迁分析物质的化学组成和空间结构,基于NMR代谢组学技术主要利用生物体液的核磁共振谱图所提供的生物体内全部小分子代谢物的丰富信息,通过对这些信息的多元统计分析,定性或者定量分析所有小分子代谢物。由于这种技术具有独特的优势,因而在肉品科学中的应用受到广泛的关注。本文介绍了NMR基本原理、NMR波谱解析和NMR代谢组学数据处理方法,综述了NMR代谢组学技术在肉品科学中的应用,为进一步阐明小分子代谢物对肉品质的影响机理提供了支持。     

Effect of essential oil active compounds on rumen microbial fermentation and nutrient flow in in vitro systems

Two experiments were conducted to determine the effects of several essential oil active compounds on rumen microbial fermentation. In the first experiment, 4 doses (5, 50, 500, and 5,000 mg/L) of 5 essential oil compounds were evaluated using in vitro 24-h batch culture of rumen fluid with a 60:40 forage:concentrate diet (18% crude protein; 30% neutral detergent fiber). Treatments were control (CON), eugenol (EUG), guaiacol, limonene, thymol (THY), and vanillin. After 24 h, the pH was determined, and samples were collected to analyze ammonia N and volatile fatty acids (VFA). The highest dose of all compounds decreased total VFA concentration and increased the final pH. Eugenol at 5 mg/L tended to reduce the proportion of acetate and the acetate to propionate ratio, at 50 and 500 mg/L tended to reduce ammonia N concentration, and at 500 mg/L reduced the proportion of propionate and branched-chain VFA concentration, without affecting total VFA concentration. All other treatments had minor effects or changes occurred only after total VFA concentration decreased. In the second experiment, 8 dual-flow continuous culture fermenters (1,320 mL) were used in 3 replicated periods (6 d of adaptation and 3 d of sampling) to study the effects of THY and EUG on rumen microbial fermentation. Fermenters were fed 95 g/d of DM of a 60:40 forage:concentrate diet (18% crude protein; 30% neutral detergent fiber). Treatments were CON, 10 mg/L of monensin (positive control), and 5, 50, or 500 mg/L of THY and EUG, and were randomly assigned to fermenters within periods. During the last 3 d of each period, samples were taken at 0, 2, 4, and 6 h after the morning feeding and analyzed for peptides, amino acids, and ammonia N concentrations, and total and individual VFA concentrations. Monensin changed the VFA profile as expected, but inhibited nutrient digestion. Eugenol and THY decreased total VFA concentration and changed the VFA profile, and only 5 mg/L of THY tended to reduce the proportion of acetate, increased the proportion of butyrate, and increased the large peptides N concentration without decreasing total VFA concentration. Most of these essential oil compounds demonstrated their antimicrobial activity by decreasing total VFA concentration at high doses. However, EUG in batch fermentation and 5 mg/L of THY in continuous culture modified the VFA profile without decreasing total VFA concentration, and EUG in batch fermentation decreased ammonia N concentration.     

Identification of the aroma compounds in stinky mandarin fish (Siniperca chuatsi) and comparison of volatiles during fermentation and storage

Identification of aroma compounds in Stinky Mandarin fish (Siniperca chuatsi) and comparison of volatiles during fermentation (with spices and salt) and storage were analysed by electronic nose (e‐nose) combining with gas chromatography–mass spectrometry (GC‐MS). Among the sixty‐one detected volatiles, thirteen aroma‐active compounds, especially linalool, were identified in stinky mandarin fish according to thresholds and concentrations. Totally, twenty‐four aroma compounds correlated well with the periods of fermentation and storage. Trimethylamine, indole, sulphur‐containing compounds, acetic acid, esters and phenols increased continually, while aldehydes decreased. According to these quality indicators, e‐nose data using principal component analysis showed a clear discrimination of the fermented fish and were in good agreement with the results of GC‐MS. In conclusion, fermentation favoured to retard spoilage and provided new aroma compounds. The technique employing an e‐nose in combination with GC‐MS could compare and identify the aroma and quality of stinky mandarin fish.     

菠萝皮渣糯米果酒发酵过程中主要成分变化研究

以菠萝皮渣和糯米为原料,进行糯米果酒发酵,并采用相关国标检测方法、液相色谱（LC）及气相色谱质谱联用（GC-MS）法,分析菠萝皮渣糯米果酒在发酵过程中可溶性固形物、酒精度、有机酸、挥发酸和香气成分等成分变化。结果表明：发酵过程中糖度迅速降低、酒精度升高后维持稳定,pH值在3.50～3.80之间,呈先降后升趋势,酸度先降低直至陈酿后期轻微升高。有机酸含量在发酵过程中总体呈下降趋势,草酸、酒石酸含量逐渐降低,柠檬酸、苹果酸、丙酮酸、乳酸含量先降后升,琥珀酸和乙酸呈上升趋势。果酒中挥发酸含量不断下降,第60天甲酸、乙酸含量分别为0.30 mg/L和0.26 mg/L。菠萝皮渣糯米果酒中共检测出88种香气成分,其中41种酯类、22种醇类、10种酸类和15种其他类,发酵过程中乳酸乙酯、乙酸异戊酯、2-甲基丁酸乙酯、正己酸乙酯、辛酸乙酯、乙酸苯乙酯、癸酸乙酯、月桂酸乙酯和十六酸乙酯含量较高,相对含量在0.27%～20.57%。     

利用NMR研究赤藓糖醇对糙米面包贮藏期间保水性的影响

利用低场核磁共振（nuclear magnetic resonance,NMR）及成像技术,研究赤藓糖醇和蔗糖对糙米面包贮藏期间保水性的影响。通过检测面包1H NMR弛豫时间、峰面积、核磁共振成像（magnetic resonance imaging,MRI）以及水分活度,得出贮藏期间面包结合水（弛豫时间T21）相对稳定,不易流动水（弛豫时间T22）和自由水（弛豫时间T23）逐渐减少,与蔗糖面包相比,添加赤藓糖醇的面包具有高水分含量和低水分活度的特点,MRI同样体现出添加赤藓糖醇的面包具有良好的保水性。     

Effect of natural and controlled fermentation on flatus‐producing compounds of beans (Phaseolus vulgaris)

Fermentation of grain legumes is an efficient method to reduce the concentration of α‐galactosidic compounds that are known to be flatulence producers. Soluble dietary fibre has also been implicated in flatulence production; however, little information exists about the effectiveness of fermentation in diminishing the effects of these compounds. The objective of this work was to study the effect of natural fermentation (NF) and controlled fermentation (CF) on the content of α‐galactosides and dietary fibre in dry beans (Phaseolus vulgaris) for 24, 48, 72 and 96 h. After 48 h, the pH during NF dropped from 6.15 to 4.00 and the nominal acidity increased six times; for CF, however, although the decrease in pH was similar to that for NF, the nominal acidity increased only three times after 48 h. Insoluble fibre content did not change the pH significantly after 96 h for NF and CF. Soluble fibre suffered an apparent removal after 48 h of NF and underwent a sharp reduction of 66% after 96 h of CF. The concentration of stachyose (the main α‐galactoside in raw beans) diminished notably after 48 h and 96 h NF (72% and 95% respectively), whereas with CF only 11% was removed after 96 h. NF of P vulgaris seems to be more effective than CF in reducing the flatulence‐producer factors (α‐galactosides and soluble dietary fibre). Copyright © 2003 Society of Chemical Industry     

发酵果蔬的功能及应用现状

随着消费者对健康饮食的日益重视,具有保健作用的发酵果蔬汁相关产品引起了研究者的广泛关注。果蔬是微生物生长的理想基质,果蔬汁发酵后会产生丰富的营养物质和多种功能活性,因此实现了果蔬高值化利用,使得未来发酵果蔬汁系列产品有着广阔的应用市场。本文综述了果蔬汁的常见发酵方式,发酵后的生物活性成分、功能活性以及发酵对果蔬汁的品质改善作用,对发酵果蔬汁行业的发展具有一定的指导意义。