Real-time monitoring of alcalase hydrolysis of egg white protein using near infrared spectroscopy technique combined with efficient modeling algorithm

The degree of hydrolysis is one of the most important indexes for process control and quality assessment in proteins enzymatic hydrolysis. This article proposed a simple and rapid near infrared spectroscopy method for real-time quantifying the degree of hydrolysis in alcalase hydrolysis process. Efficient variables selection algorithms were systemically studied in multivariate calibrations; the partial least squares coupled with uninformative variables elimination and ant colony optimization were proposed for modeling with results yielding Rp = 0.9525. Additionally, 10 independent samples with the relative error less than 10% further confirmed the stability and reliability of this method. This work demonstrated that the near infrared spectroscopy technique with a selected multivariate calibration has a high potential for in situ monitoring of alcalase hydrolysis process in protein industry.     

如何选择糖果用油脂

<正> 油脂为糖果食品提供独特的性质,它能决定食品的感观特性、加工特性、稳定性和营养特性。选用适当的专用油脂产品能为开发新食品,改进现有产品的味道、质量和方便性等提供一定的有利条件。本文将深入探讨油脂的功能特性,生产商从而能选择适当的专用油脂,生产出外观、质地、风味、营养等俱佳的糖果食品。     

Evaluation of Fatty Acid Profile of Wagyu Beef by ATR-FTIR Spectroscopy

Japanese black Wagyu beef has its characteristics of fatty well-marbled texture, flavor, and tenderness which are affected by fatty acid composition. The aim of this study was to develop an analytical method for evaluating the fatty acid profile of Wagyu beef by Fourier transform infrared (FTIR) spectroscopy. In the current study, attenuated total reflection–FTIR (ATR-FTIR) spectroscopy and gas chromatography (GC) were applied to the fat tissues, and the solvent-extracted fats which were sampled from subcutaneous, inter- and intramuscular fat tissues. Results of GC analysis showed that monounsaturated fatty acids (MUFA) content became larger in the order of intramuscular, intermuscular, and subcutaneous fats, and saturated fatty acids (SFA) became smaller in the same order. Subcutaneous fat could be discriminated from inter- and intramuscular fats on the basis of fatty acid composition by principal component analysis. The ATR-FTIR analysis revealed that the shift of the peak positions of alkene C–H stretching vibration at around 3,006 cm⁻¹ occurred depending on the unsaturation degree of fatty acids in beef fat. Partial least squares (PLS) regression analysis with leave-one-out cross-validation was applied to the combined regions of 2,800–3,050 and 1,000–1,500 cm⁻¹ for the fat tissues and the extracted fats. The correlation coefficients of the PLS validation models predicting the content of the MUFA and SFA for solvent-extracted fats were higher than those for fat tissues, and the coefficients (R ²) of determination more than 0.873 were obtained for solvent-extracted fats and 0.522 for fat tissues.     

基于衰减全反射傅里叶变换红外光谱的餐饮废油掺假检测

为了建立基于衰减全反射傅里叶变换红外光谱(ATR-FTIR)的餐饮废油掺假检测方法,以常见食用油和餐饮废油为原料,收集8个餐饮废油和25个食用油样品,制备30个掺假油样品,共63个油样进行红外光谱扫描。随机取48个油样作为校正集样品,15个油样作为验证集样品,建立餐饮废油定性分析模型,并对定性模型进行验证;从30个掺假油样品中,随机取20个油样作为校正集样品,10个油样作为验证集样品,建立餐饮废油定量分析模型,并对定量模型进行验证。结果表明:在红外光谱范围为1 550~650 cm-1条件下,采用原始光谱结合判别分析建立定性分析模型,其识别率可达100%;采用偏最小二乘法(PLS)建立定量分析模型,在掺假比例1%~10%时,模型预测值与实际掺假比例呈良好的线性关系,相关系数(R)为0.982 2,标准偏差(SD)为0.47。表明基于ATR-FTIR的餐饮废油掺假检测是可行的。     

Near-infrared reflectance spectroscopy for the prediction of chemical composition in walnut kernel

In the present work, 116 samples were collected and near-infrared reflectance spectroscopy prediction model for determination of moisture, protein, and fat contents of walnut meal were obtained and evaluated. All the samples were analyzed based on the chemical methods. Meanwhile, they were scanned to obtain their near-infrared reflectance spectrum in the wavelength range of 570–1840 nm. Several preprocess treatments including scattering pretreatments, mathematical pretreatments, and aggression methods were optimized to increase the accuracy of the calibration models according to the coefficient of determination for calibration (R_c²) and the cross-validation (one minus the variance ratio, 1-VR), and the standard error of calibration and cross-validation. The results showed modified partial least square loading was the better aggression method to predict the moisture, proteins, and fats in walnut kernel. The calibration equations obtained indicated that near-infrared reflectance spectroscopy had excellent predictive capacity for the three components with R_c² = 0.965, standard error of calibration = 0.052 for moisture, and R_c² = 0.967, standard error of calibration = 0.191 for proteins, and R_c² = 0.979, standard error of calibration = 0.171 for fats, respectively. The external validation further confirmed the robustness and reliability of the near-infrared reflectance spectroscopy prediction models with the correlation coefficient of actual and predicted values (R²) = 0.952, ratio of performance deviation = 4.14, the standard error of prediction =0.058 for moisture, and R² = 0.977, ratio of performance deviation = 5.55, standard error of prediction = 0.182 for proteins, and R² = 0.990, ratio of performance deviation = 8.64, standard error of prediction = 0.191 for fats, respectively. Near-infrared reflectance spectroscopy is a reliable technology to predict these constituents in walnuts.     

The influence of combined emulsifier 2 in 1 on physical and crystallization characteristics of edible fats

The aim of this research was to examine the physical and crystallization characteristics of two type of edible fats with the addition of combination of two kind of emulsifiers and with the addition of, so-called, combined emulsifier 2 in 1. NMR technique was used for measuring the solid fat content (SFC) of fats on different temperatures, as well as for crystallization rate under static conditions, by measuring the change of SFC in a function of time. Also, the possibility of applying of Gompertz’s mathematical method to define kinetics of crystallization was investigated. The hardness of fats was defined by penetration on texture analyser, while the rheological properties were determined using the rotational rheometer. The samples of both fats with emulsifier 2 in 1 added have a lower crystallization rate with less amounts of crystals formed, which indicates better spreadability comparing with samples that contain the combination of two emulsifiers. This is also shown by physical determination, since emulsifier 2 in 1 significantly reduced the values of hardness and work of shearing, as for the values of yield stress and tixotropy curve area. Emulsifier 2 in 1 would significantly facilitate the handling in confectionery industry because it can be used instead of the combination of two different type of emulsifiers, which are usually combined in order to give the necessary technological characteristics of confectionery products that contain the fat phase. Also, this emulsifier would improve the quality of those products since it showed better emulsifying properties than combination of two different emulsifiers.     

Production of stearate-rich butters by solvent fractionation of high stearic–high oleic sunflower oil

Cocoa butter equivalents (CBEs) are fats with a similar composition and melting profile as cocoa butter (CB), which are usually prepared by blending mid-palm fractions and stearate-rich tropical butters. In this regard, high stearic–high oleic sunflower oil contains disaturated triacylglycerols typically present in CBEs, albeit at a lower concentration than that required to produce a solid fat. Here we have assessed a means to fractionate this oil in order to produce solid fractions that can be used as stearic acid-rich butters appropriate for CBE formulations. Solvent fractionation of high stearic–high oleic sunflower oil was optimised in function of the oil/solvent ratio and temperature. Sunflower stearins with similar melting profiles as cocoa butter were obtained from oils of either 17% or 20% stearic acid in a single step. Different stearin products can be obtained by controlling the oil/solvent ratio and the temperature of fractionation. The use of these fractions as CBE components or confectionery fats is discussed in function of their melting profiles.     

Medium chain and behenic acid incorporated structured lipids from sal,mango and kokum fats by lipase acidolysis

Medium chain (MC) and behenic fatty acids were incorporated into kokum, sal and mango fats using 1,3-specific lipase catalysed acidolysis. The incorporation of fatty acids increased with increase in concentration of fatty acids and duration of reaction. The order of incorporation of fatty acids was C22:0 > C10:0 > C8:0, to the extent of 53%, 42.5%, 35.8%, respectively, after 16 h, using kokum as substrate. The same trend was observed with sal or mango fats as substrates though the percentages incorporated were different. The modified products with higher contents of MC were liquids with no solid fats, even at 0 °C, and which showed low cloud point due to an increase in triacylglycerols containing lower chain fatty acids. The modified products after incorporating both MC and C22:0 showed long melting ranges and were suitable for use in bakery, confectionery, etc. as vanaspati substitutes.     

Physical and Chemical Properties of Randomly Interesterified Blends of Corn Oil and Tallow

The sodium methylate-catalyzed random interesterification of corn oil-tallow blends was explored in order to develop plastic fats of varying physical properties. Lipase hydrolysis of the randomized fats showed that with 0.5% catalyst, interesterification was completed within 30 min at 80°C. Interesterification decreased the melting point and solid fat index of the randomized fats. The trans- fatty acid level and fatty acid profile of the rearranged fats did not show any change upon interesterification. The oxidative stability of the fats decreased after random interesterification, but addition of 0.01% citric acid and 0.01% butylated hydroxyanisole produced a fat blend of comparable stability to commercial margarine oils.     

The contribution of food groups to the nutrient intake and food pattern among pre-school children

A pre-school-based dietary survey, using 7-day records, was carried out in Sweden in the Stockholm area at 12 pre-schools; the survey included 109 of 131 participating children. The present study was designed to describe weekday and weekend food patterns, i.e. the frequency of consumption of food items and the contribution of energy and nutrient intake from different food groups, and to explore how foods are related in pre-school children's diet. At pre-school, all children except one ate vegetables and fruits about once a day, and all children consumed, on average, milk and cheese, meat products, bread and breakfast cereals and fats more than once a day. Milk and cheese products, bread and breakfast cereals and meat products were the primary source of energy and protein. The main source of dietary fibre was bread and breakfast cereals, potatoes and fruits. The “low-nutrient foods”, e.g. confectionery, buns, and soft drinks, contributed 20% of the energy during the weekdays and 33% during the weekend days. When all food groups (g/MJ) were analysed simultaneously in a Principal Components Analysis (PCA), 52% of the variation was explained. The food consumption data were described using four food clusters: milk and cheese products; bread and breakfast cereals; meat, potatoes and cooked cereals; confectionery, buns and soft drinks. In conclusion, the PCA seems to be a useful visual tool for elucidating how foods are related in the diet.     

Predicting condensed tannin concentrations in Lotus uliginosus Schkuhr using near-infrared reflectance spectroscopy

Near-infrared reflectance spectroscopy (NIRS) was used to develop equations to predict condensed tannins (CT) in greater lotus (Lotus uliginosus Schkuhr) with a precision satisfactory for the screening of genotypes in a plant breeding programme. NIRS equations were developed using both partial least squares and stepwise multiple linear regression techniques, and a wide range of mathematical treatments of the log 1/reflectance NIRS data. In general, equations developed using partial least squares regression techniques had 10–15% lower standard errors than those developed using stepwise multiple linear regression, during both calibration and prediction. Standard errors of calibration ranged from 10 to 17 g kg⁻¹, standard errors of prediction from 12 to 17 g kg⁻¹. These errors equate to coefficients of variation in the order of 20% The use of NIRS to predict CT in greater lotus will allow more rapid evaluation and selection of genotypes than could be achieved using butan-1-ol/HCl hydrolysis. © 1997 SCI.     

糙米中黄曲霉毒素B1的ATR-FTIR快速测定

拟建立基于衰减全反射-傅里叶变换红外光谱（attenuated total reflectance-Fourier transform infraredspectroscopy,ATR-FTIR）的糙米中微量黄曲霉毒素B1（aflatoxin B1,AFB1）的快速检测方法。首先将16 份糙米样品经辐射灭菌后接种产毒菌株并在适宜条件下（28 ℃、相对湿度85%）贮藏30 d,测定其AFB1含量。其次将受AFB1污染样品磨粉后与空白糙米样品按质量比例进行精确混合,获得AFB1含量在0～890.20 μg/kg内的糙米样品共计128 份。ATR-FTIR建模分析结果显示,依据AFB1含量高低将样品划分为4 类,临近算法判别分析模型的预测整体正确率达到83.3%。运用偏最小二乘回归分析建立的定量模型精度最优,预测相关系数、均方根误差和相对分析误差值分别为0.970、70.8 μg/kg和4.0。结果表明,ATR-FTIR技术用于糙米黄曲霉毒素污染程度的快速分析与筛选具有一定可行性,但需进一步研究来提升对低AFB1含量样品的预测精度。     

Comparative characterisation of dioxane-soluble lignins released by ball milling and by sheep digestion from forage grasses

Faecal soluble lignin (FSL), extracted from the faeces of sheep that received orchardgrass and timothy, were compared with 90% dioxane-soluble lignins released by ball milling (MHL) and by subsequent enzymatic hydrolysis (EHL) from the same grasses. FSL contained much less carbohydrate and esterified p-coumaric and ferulic acids than MHL and EHL. Although no considerable differences were found in the yields of vanillin and syringaldehyde produced by nitrobenzene oxidation, the molar ratio of syringaldehyde to vanillin was higher for FSL than for MHL and EHL. Such differences in chemical properties among the lignin preparations were confirmed by ¹³C-NMR spectroscopy. FSL had a lower molecular size compared with MHL and EHL. Results indicated that syringyl-rich lignin fragments with less phenolic acid esters, probably depolymerisation products of the grass lignins, were released by digestion in sheep from the forage grasses.     

Uses for dairy ingredients in confectionery

Milk products are important ingredients for the confectionery industry. Milk solids may be added to chocolate either in the form of chocolate crumb or through the addition of milk powder. Roller-dried powder is preferable to spray-dried powder but is increasingly difficult to obtain. Milk fat has an advantage over other fats in that it is compatible with cocoa butter. Whey and whey-derived products such as protein concentrates and lactose or whey syrups also have potential applications, particularly in toffee manufacture where there are no legal restrictions on composition and some of the properties of the milk products may be advantageous.     

氯仿-甲醇法和酸水解法测定禽蛋中脂肪的方法比较

目的 对比富含磷脂等结合态脂肪的蛋制品中脂肪含量测定的方法,弥补目前国标中规定的酸水解检测方法无法准确地测定富含磷脂等结合态脂肪样品的不足。方法 采用氯仿－甲醇提取法对比国标中规定的蛋制品脂肪测定方法-酸水解法,测定蛋制品中的脂肪含量, 考察了两种方法测定不同蛋制品的提取结果、提取时间、精密度和重复性。结果 采用氯仿－甲醇法对比酸水解法提取蛋制品中的脂肪含量,结果表明,氯仿-甲醇提取法可以有效的提取蛋制品的磷脂等结合态脂肪,对蛋制品脂肪的测定具有较高的精密度和较好的重复性,相对标准偏差在0.91%-1.62%之间,且测定周期短,测定次数少。结论 氯仿－甲醇法弥补了酸水解法水解磷脂的不足且测定快速、准确,适合测定蛋制品中的脂肪含量。     

A Fourier Transform Infrared Spectroscopy Method for Analysis of Palm Oil Adulterated with Lard in Pre-Fried French fries

Fourier transform infrared spectroscopy with attenuated total reflectance accessory was used to detect the presence of lard in French fries pre-fried in palm oil adulterated with lard. A Fourier transform infrared calibration model was obtained using partial least squares for prediction of lard in a blend mixture of lard and palm oil. The coefficient of determination (R²) of 0.9791 was obtained with 0.5% of detection limit. The error in calibration expressed with root mean square error of calibration was 0.979%. In addition, the error obtained during cross validation was 2.45%. A discriminant analysis test was able to distinguish between fries samples adulterated with lard and samples, which were pre-fried with palm oils. Fourier transform infrared spectroscopy is a fast and powerful technique for quantification of lard present in French fries.      

Structural features of the polysaccharide gum from Acacia glomerosa

Acacia glomerosa, Benth. (Vulgares Series) exudates a clear gum which produces gels easily. The physico-chemical data and sugar composition are very close to gum arabic from Acacia senegal, except that A. glomerosa gum contains a high nitrogen content. A series of degraded products was prepared by acid hydrolysis and Smith-degradation. The characterization of the degraded products by partial hydrolysis, sugar composition and by the application of uni- and bidimensional spectroscopy led to know interesting structural features of the polysaccharide isolated from A. glomerosa gum. This polysaccharide, as that from A. senegal gum, consists of 1,3-β- -galactopyranosyl backbone. There are side-chains of 1,3-β- -galactopyranosyl oligosaccharides attached to position six of the galactan main chain. Arabinose (furanosyl and pyranosyl) residues may be up to four units long because it was necessary to prepare four polysaccharides to remove them from the gum structure. Uronic acid residues were difficult to remove as has been observed in other Acacia gums.     

ATR-FTIR在小麦及其制品呕吐毒素污染水平快速测定中的应用

为快速测定小麦及其制品呕吐毒素（deoxynivalenol,DON）污染情况,搜集小麦、面粉及面粉制品共98?份,利用衰减全反射-傅里叶变换红外光谱（attenuated total reflectance-Fourier transform infrared spectroscopy,ATR-FTIR）获取样品在4 000～600 cm－1的光谱信息,对样品中的DON含量建立了基于偏最小二乘回归（partial least squares regression,PLSR）分析和逐步多元性回归（stepwise multiple linear regression,SMLR）分析方法的定量分析模型。结果显示,不同DON含量样品在1?740、1?648、1?549?cm－1和1?300～900?cm－1等波段处的吸收值存在显著差异。PLSR和SMLR均能较好预测样品中的DON含量,其中PLSR模型的预测集决定系数RP2、预测均方根误差（root mean squared error of prediction,RMSEP）和相对分析偏差（residual predictive deviation,RPD）值分别为0.86、0.438?mg/kg和2.6。SMLR结合9?个波长所建模型的RP2、RMSEP和RPD值分别为0.86、0.426?mg/kg和2.6。结果表明,ATR-FTIR用于小麦及其制品DON污染快速分析具有可行性。     

Trans fatty acid content in Malaysian supermarket foods: a field-to-laboratory approach in assessing food risk

The extent of industrial trans fatty acids (TFA) in the food supply is unknown in Malaysia, whilst TFA disclosure on food labels is not mandatory by Malaysian food standards. Supermarket foods such as dairy products, fats and oils, meat products, snack foods, soups, and confectionery are commonly cited to be major contributors of TFA in the diet. A consumer survey (n = 622) was used to develop a food listing of these ‘high risk’ foods. TFA content of high-risk foods were analysed by gas chromatography. Food samples (n = 158) were analysed and their total TFA content were compared with Malaysian Food Standards. A wide variation in TFA content within food categories was indicated. Of the foods containing TFA, many food labels did not cite TFA content or the use of partially hydrogenated vegetable oils (PHVO) as an ingredient. Hypothesised estimates of TFA intake from these supermarket foods in a sample day’s menu providing 2000 kcal projected a minimum intake of 0.5 g and a maximum intake of 5.2 g TFA. This study found there was no voluntary disclosure of TFA content on food labels or identifying PHVO as an ingredient. It appears that health education targeting consumers to minimise TFA consumption is required supported by mandatory PHVO disclosure on the food label.     

Highly efficient preparation of free all-trans-astaxanthin from Haematococcus pluvialis extract by a rapid biocatalytic method based on crude extracellular enzyme extract

A highly efficient, rapid, green and safe procedure for the preparation of free all-trans-astaxanthin from Haematococcus pluvialis algal extract, by a crude extracellular enzyme extract, was reported. The free all-trans-astaxanthin obtained by the biocatalysed method had fewer side products compared to the saponification procedure. Through single-factor experiments and a Box–Behnken design, it was possible to find the optimal biocatalytic conditions for the hydrolysis of 2 mg of H. pluvialis oil with 14.7 mg (protein content) of lyophilised crude extracellular enzyme extract obtained from Pseudomonas aeruginosa. The reaction was carried out in 30 min at pH 9.16 and 36 °C, in 5.5 mL total reaction volume, under nitrogen atmosphere and dark conditions. The hydrolysis ratio of the astaxanthin esters was 98.72%, and the production of free all-trans-astaxanthin was 82.83 μg per mg of H. pluvialis oil. The method herein reported was simpler than other enzymatic methods previously described and allowed saving of time and costs.