食醋中勾兑工业合成醋酸的调查分析

目的了解杭州地区市售食醋勾兑醋酸的现状,为今后质量监督执法和评价提供科学依据。方法对杭州地区流通领域的食醋进行了抽样检测分析,采用相关强制性国家标准进行判定。结果本次对杭州地区流通领域的61个食醋样品进行了勾兑合成醋酸检测分析,其中酿造食醋51个样品,配制食醋10个样品,根据GB1903—2008《食品添加剂冰乙酸(冰醋酸)》标准酿造醋酸比率(天然度)%≥95%判定,酿造食醋合格率为96.08%,配制食醋合格率为70.00%,配制食醋的掺假现象比酿造食醋严重。结论今后应进一步加强食醋勾兑合成醋酸的风险监测力度,确保食醋质量安全。     

SNIF-NMR和IRMS技术在葡萄酒质量评价中的初步研究

利用SNIF-NMR和IRMS技术测定葡萄酒中稳定性同位素D/H和18O/16O的比值。结果表明,通过测定乙醇分子中甲基位(D/H)Ⅰ和次甲基位点(D/H)Ⅱ的含量,可判断葡萄酒在酿造前是否进行了加糖操作,而通过测定葡萄酒水分中18O/16O的比值,可鉴别全汁葡萄酒和半汁葡萄酒。研究结果为中国葡萄酒的质量评价提供了一种新的技术手段。     

Rapid detection of fat adulteration in bakery products using Raman and near-infrared spectroscopies

Adulteration is frequently encountered in the food industry and can be identified using currently available techniques. Infrared and Raman spectroscopic procedures are the most attractive techniques regarding fats and oils. The objective of this study was to determine the adulteration of the fat source (margarine or butter) in bakery products using Raman and near-infrared (NIR) spectroscopies. Margarine and butter samples were purchased at local markets in Turkey and examined using Raman and NIR devices. A mixture (50 % margarine : 50 % butter) of fat samples was examined as well. The NIR and Raman spectral output data of all the fat samples were processed using principal component analysis (PCA). Good classification was obtained for margarine, butter and the 1:1 adulterated mixture. The chosen bakery product (cake) was produced using the same fat samples according to the method of the American Association of Cereal Chemists. Then, the fat fraction was extracted from the cakes with n-hexane. Extracted fat samples from the cakes were examined as before. PCA was applied to Raman and NIR spectral data to achieve the separation of fat sources in the cakes. PCA was also validated in each of the two stages. Significant decomposition was observed in the Raman study in contrast to the NIR study. A chemometric comparison was also applied to processed (baked) fat samples in cakes and purchased samples by PCA to assess the effects of heat treatment on sample spectra. Raman spectroscopy with multivariate analyses such as PCA can be used to detect the adulteration of the fat source in bakery products in a faster and more suitable way than the other methods.     

A PCR assay for detection of acetic acid-tolerant lactic acid bacteria in acidic food products

A PCR assay for the detection of acetic acid-tolerant lactic acid bacteria in the genera of Lactobacillus and Pediococcus was developed in this study. Primers targeting the bacterial 16S rRNA gene were newly designed and used in this PCR assay. To determine the specificity of the assay, 56 different bacterial strains (of 33 genera), 2 fungi, 3 animals, and 4 plants were tested. Results were positive for most tested bacterial members of 16S rRNA gene-based phylogenetic groups (classified in the Lactobacillus casei and Pediococcus group), including Lactobacillus fructivorans, Lactobacillus brevis, Lactobacillus buchneri, Lactobacillus plantarum, and Lactobacillus paracasei. For all other bacterial strains and eukaryote tested, results were negative. Bacterial DNA for PCR was prepared with a simple procedure with the use of Chelex 100 resin from culture after growth in deMan Rogosa Sharpe broth (pH 6.0). To test this PCR assay for the monitoring of the acetic acid-tolerant lactic acid bacteria, L. fructivorans was inoculated into several acidic food as an indicator. Before the PCR, the inoculation of 10 to 50 CFU of bacteria per g of food was followed by a 28-h enrichment culture step, and the PCR assay allowed the detection of bacterial cells. Including the enrichment culture step, the entire PCR detection process can be completed within 30 h.     

光学快速分析技术在食品掺假检测中的应用

光学快速分析技术作为一种快速无损的检测技术已在食品行业中得到应用。文章综述近红外光谱、拉曼光谱、高光谱成像等光学快速分析技术在食品掺假检测中的应用,包括乳制品掺假、食用油掺假、肉制品掺假和其他食品掺假等方面,同时提出现阶段光学快速分析技术所存在的问题,并简要展望该技术在食品掺假检测领域的前景。     

Application of immunological methods for the detection of species adulteration in dairy products

A number of enzyme‐linked immunosorbent assays (ELISAs) have been developed for the detection of milk adulteration in dairy products. Target antigens have been caseins, lactoglobulins, immunoglobulins and other whey proteins. Polyclonal and monoclonal antibodies have been used in a variety of formats including direct, indirect, competitive and sandwich ELISAs. ELISAs have been successfully applied to the detection of cows' milk adulteration of sheep, goat and buffalo milk. Goat milk adulteration of sheep milk has also been detected. A number of ELISAs have also been applied to cheese. It is recommended that ELISA should be used in combination with PCR to ensure compliance with current legislation.     

电子舌快速检测食用植物油掺伪

目的应用法国Alpha M.O.S公司生产的传感器型味觉电子舌系统对3组不同程度掺伪的食用植物油进行掺伪检测。方法选取6种不同类型植物油,用20%的乙醇浸泡后超声,静置隔夜,将油脂中的味觉信息提取出来,由电子舌自动进样系统采集原始数据,所得样品数据用主成分分析法、判别因子法进行分析。结果 2种方法均能较好地检测区分不同的食用植物油样品,大部分的指纹分辨指数高于95分。此方法可以区分不同榨取工艺或不同产地的同种类油脂,可鉴别的掺伪检测限为0.1%。结论本实验鉴别精确度远大于常规的油脂检测方法,且具有较高的灵敏度,能够快速有效地鉴别不同种类食用植物油并区分不同掺杂比例的油脂样品。     

基于三维荧光光谱的花生油掺伪快速检测研究

建立一种基于三维荧光光谱的花生油掺伪检测方法。以纯花生油和掺伪4种常见植物油的花生油为研究对象,将三维荧光光谱图处理转化为灰度图,利用Zernike图像矩直接提取三维荧光光谱灰度图的特征信息,得到的特征信息数据通过Xgboost算法和广义回归神经网络（GRNN）算法分别建立定性和定量掺伪判别模型并对其进行验证。结果表明：Xgboost算法可以有效地对掺伪的花生油进行鉴别,并准确解析其掺伪具体成分;GRNN算法可定量预测花生油掺伪含量,各检出限分别为掺伪大豆油0.2%、掺伪菜籽油1.5%、掺伪玉米油1.0%、掺伪葵花籽油0.5%。因此,该方法可对花生油掺伪进行定性和定量分析,具有快速、简便、灵敏度高等优点。     

Hydrogen production by fermentation using acetic acid and lactic acid

Microbial hydrogen production from sho-chu post-distillation slurry solution (slurry solution) containing large amounts of organic acids was investigated. The highest hydrogen producer, Clostridium diolis JPCC H-3, was isolated from natural environment and produced hydrogen at 6.03+/-0.15 ml from 5 ml slurry solution in 30 h. Interestingly, the concentration of acetic acid and lactic acid in the slurry solution decreased during hydrogen production. The substrates for hydrogen production by C. diolis JPCC H-3, in particular organic acids, were investigated in an artificial medium. No hydrogen was produced from acetic acid, propionic acid, succinic acid, or citric acid on their own. Hydrogen and butyric acid were produced from a mixture of acetic acid and lactic acid, showing that C. diolis. JPCC H-3 could produce hydrogen from acetic acid and lactic acid. Furthermore, calculation of the Gibbs free energy strongly suggests that this reaction would proceed. In this paper, we describe for the first time microbial hydrogen production from acetic acid and lactic acid by fermentation.     

Enhanced 2,3-butanediol production by addition of acetic acid in Paenibacillus polymyxa

By the addition of 150 mM acetate into a batch culture at an initial pH of 6.8, the production of 2,3-butanediol (BDL) by Paenibacillus polymyxa reached 248 mM, yielding 0.87 mol.mol(-1) glucose, where the ratio of acetate consumed to glucose consumed (A/C ratio) was calculated as 0.35 mol acetate mol(-1) glucose. Therefore, a fed-batch culture was carried out by feeding glucose and acetate at a ratio of 0.35 mol acetate mol(-1) glucose. In the fed-batch culture performed at pH 6.8, BDL production reached 637 mM, yielding 0.81 mol.mol(-1) glucose, although the A/C ratio was only 0.18 mol acetate mol(-1) glucose. By decreasing pH to 6.3 in the fed-batch culture, BDL production reached 566 mM, yielding 0.88 mol.mol(-1) glucose and the A/C ratio was 0.32 mol acetate mol(-1) glucose. The optical purity of BDL, which was expressed as enantiomeric excess, was retained at more than 98% of the (R, R)-stereoisomer at the end of culture, which was comparable to that without acetate addition.     

掺假羊乳及其制品中牛乳的检测技术研究进展

羊乳具有营养价值高、蛋白质组成更接近人乳、脂肪球直径小及致敏性低等优点,更利于人体消化吸收,受到消费者和乳品企业的青睐.近年来我国羊乳产业发展迅速且潜力巨大,但由于受羊乳产量和养殖规模的限制,羊乳价格昂贵,市场中存在羊乳及其制品掺假牛乳的现象,且掺假手段多样,难以辨别.为了保证消费者的健康和权益,保障羊乳市场良性发展,...     

肉类掺杂掺假的高光谱成像检测研究进展

肉类的掺杂掺假是国内外普遍关注的公共安全问题,对社会经济、健康、环境等方面具有潜在影响.近年来,不法商家为牟取暴利导致肉类掺杂掺假现象层出不穷、多种多样,针对此类问题研究行之有效的检测技术与方法以保障肉品真实性具有重要意义.高光谱成像技术以快速、非侵入、图谱合一等优势在食品农产品检测领域发展迅速,不仅可同时提取图像及光...     

Rapid detection and quantification of milk adulteration using infrared microspectroscopy and chemometrics analysis

The application of attenuated total reflectance mid-infrared microspectroscopy (MIR-microspectroscopy) was evaluated as a rapid method for detection and quantification of milk adulteration. Milk samples were purchased from local grocery stores (Columbus, OH, USA) and spiked at different concentrations of whey, hydrogen peroxide, synthetic urine, urea and synthetic milk. Samples were place on a 192-well microarray slide, air-dried and spectra were collected by using MIR-microspectroscopy. Pattern recognition analysis by Soft Independent Modeling of Class Analogy (SIMCA) showed tight and well-separated clusters allowing discrimination of control samples from adulterated milk. Partial Least Squares Regression (PLSR) showed standard error of prediction (SEP) ∼2.33, 0.06, 0.41, 0.30 and 0.014 g/L for estimation of levels of adulteration with whey, synthetic milk, synthetic urine, urea and hydrogen peroxide, respectively. Results showed that MIR-microspectroscopy can provide an alternative methodology to the dairy industry for screening potential fraudulent practice for economic adulteration of cow’s milk.     

Determining the level of dehydroascorbic acid in food products

Ascorbic acid stability was studied under conditions of dehydroascorbic acid assay. The minimum amounts of cysteine and volumes of reagents utilized were specified. Based on the data of 2,6-dibromoindophenol stability the method of indophenol-xylol extraction was proved to be unsatisfactory for the assay of dehydroascorbic acid.     

Natural origin of ascorbic acid: Validation by C NMR and IRMS

A new method for the extraction and purification of ascorbic acid from two tropical fruits (acerola and camu-camu) is presented. ¹³C nuclear magnetic resonance and isotopic ratio mass spectroscopy (¹³C/¹²C) were used to recognize ascorbic acid coming from either natural or industrial sources. A quantitative ¹³C NMR procedure was optimized to calculate isotopic relative abundances on each molecular site; data were treated by a multivariate method.     

Analysis of proteins responsive to acetic acid in Acetobacter: molecular mechanisms conferring acetic acid resistance in acetic acid bacteria

Acetic acid bacteria are used for industrial vinegar production because of their remarkable ability to oxidize ethanol and high resistance to acetic acid. Although several molecular machineries responsible for acetic acid resistance in acetic acid bacteria have been reported, the entire mechanism that confers acetic acid resistance has not been completely understood. One of the promising methods to elucidate the entire mechanism is global analysis of proteins responsive to acetic acid by two-dimensional gel electrophoresis. Recently, two proteins whose production was greatly enhanced by acetic acid in Acetobacter aceti were identified to be aconitase and a putative ABC-transporter, respectively; furthermore, overexpression or disruption of the genes encoding these proteins affected acetic acid resistance in A. aceti, indicating that these proteins are involved in acetic acid resistance. Overexpression of each gene increased acetic acid resistance in Acetobacter, which resulted in an improvement in the productivity of acetic acid fermentation. Taken together, the results of the proteomic analysis and those of previous studies indicate that acetic acid resistance in acetic acid bacteria is conferred by several mechanisms. These findings also provide a clue to breed a strain having high resistance to acetic acid for vinegar fermentation.     

Analysis of potential lard adulteration in chocolate and chocolate products using Fourier transform infrared spectroscopy

Fourier transform infrared (FTIR) spectroscopy, in combination with attenuated total reflectance (ATR) and partial least square (PLS) regression, was used to detect the presence of lard in chocolate formulation. The spectral bands associated with lard, cocoa butter and their blends (ranging from 0% to 15% of lard in cocoa butter) were recorded, interpreted and identified. A semi-quantitative approach is proposed to measure the percent of lard in blends on the basis of spectral data at the frequency region 4000–650 cm⁻¹, using the equation y = 0.9225x + 0.5539. The coefficient of determination (R²) was 0.9872 with a standard error (SE) of 1.305. In this paper, the potential of FTIR spectroscopy as a rapid analytical tool for the quantitative determination of adulterants especially lard, in chocolate, is demonstrated.     

肉制品中毛皮动物源性成分掺假检测阳性质粒分子的构建与评价

目的 建立一种肉制品中毛皮动物源性成分掺假快速检测技术。方法 构建狐狸、貉、水貂三种检测用阳性质粒分子,利用实时荧光定量PCR方法对其特异性、灵敏度和方法适用性等关键指标进行分析。结果 构建好的狐狸、貉、水貂阳性质粒分子特异性强、灵敏度高,检验灵敏度均可达到10-4 ng/μL,标准曲线扩增效率分别为94.451%、117.461%、114.709%,且相关系数(R2)均在0.995以上。在混合肉样品和市售肉制品中均可检测,三种成分的检测限均低至1%,具有较好的可行性及适用性。结论 本方法构建的三种阳性质粒分子可以满足实际工作中肉类掺假检测的需求。     

拨开乌云见青天方识庐山真面目——对食品添加剂醋酸现状的忧虑和呐喊

随着配制食醋标准的出台，调味品行业对醋酸的需求量也增加，但市场中也出现了大量低质量的食品添加剂醋酸。从市场、醋酸生产等方面分析了食品添加剂醋酸的现状，并针对现状提出意见和对策。