提高大豆渣膳食纤维中可溶性成分的方法研究

以大豆渣为原料,采用微生物发酵、微射流均质机高压均质处理和高温蒸煮的方法来提高大豆膳食纤维中可溶性成分含量,研究不同发酵时间、不同处理压力和蒸煮温度以及蒸煮时间对提高豆渣可溶性膳食纤维（SDF）含量的影响。结果表明：利用发酵法可提高可溶性膳食纤维的含量达15%之多,并且在发酵的前6天,SDF含量增长很快,6 d后SDF的含量变化较少;而高压均质处理法提高可溶性膳食纤维含量的幅度在10%～28%之间,并随着处理压力的升高而增大;高温蒸煮法能提高可溶性膳食纤维的含量20%,121℃,20 min为较理想的蒸煮条件。     

Simplified method for determination of total dietary fiber in foods

A simplified method, based on the same principles as the AOAC enzymatic-gravimetric method for determining total dietary fiber (TDF) (43.A14-43.A20), has been tested on 12 food samples which had been used in other collaborative studies. TDF values obtained in our laboratory for these 2 methods were in good agreement (y = 0.96x + 0.39; r = 0.999). The simplified method uses a single incubation period and only 1 enzyme (amyloglucosidase), and thus yields smaller blank and ash corrections but a higher protein correction.     

Urea enzymatic dialysis procedure for determination of total dietary fiber

A method that uses urea and enzymes for determination of total dietary fiber (TDF) in foods has been developed and compared with the AOAC enzymatic-gravimetric method (43.A14-43.A20). In the evaluation, results for crude protein and ash contamination were higher by the AOAC method, particularly for samples that form gels during ethanol precipitation. The new urea enzymatic dialysis (UED) method quantitatively recovered, with less variation, more of the purified and semipurified dietary fiber products. TDF recoveries for carboxymethylcellulose and locust bean gum were 98% (SD 3.3) and 95% (SD 6.1) by the AOAC method and 99% (SD 1.0) and 100% (SD 0.6) by the UED method, respectively. The UED method was the more effective in removing starch. For kale samples, starch recovery was 3.5 and 0.2% from TDF residues obtained using the AOAC and UED methods, respectively. Differences were not significant among replicate values for determination of TDF in foods by the UED method (P greater than 0.01). Preliminary studies suggest that the new method can separately determine soluble and insoluble dietary fiber. The data indicate that the UED method is more precise and accurate than the AOAC method.     

Determination of total dietary fiber in Japanese foods.

Total dietary fiber was determined in Japanese foods by the Prosky-AOAC method. To accomplish the analyses of unsuitable samples, we introduced a few minor modifications to the versions for (i) seaweed and fruits, (ii) cereals, and (iii) fish and meats. These modified methods were used together with the standard method to obtain results with reasonably good relative standard deviation for 231 foods and 21 groups of mixed foods. In this study, dietary fiber was defined so as not to exclude the nondigestible polysaccharide portions of animal foods. A method was proposed which could estimate more accurately the fiber components of animal foods by measuring the "nondigestible protein" of the fiber sample of the fiber sample by the Biuret colorimetric method, instead of the Kjeldahl method, to avoid deducting the values for aminopolysaccharides. In Japanese diets, the amount of fiber obtained from animals foods was less than 5% of the total intake of dietary fiber.     

Near-infrared analysis of soluble and insoluble dietary fiber fractions of cereal food products

The use of near-infrared (NIR) reflectance spectroscopy for the rapid and accurate measurement of soluble and insoluble dietary fiber was explored in a diverse group of cereal products. Ground samples were analyzed for soluble and insoluble dietary fiber (AOAC Method 991.43) and scanned (NIRSystems 6500 monochromator) to obtain NIR spectra. Modified PLS models were developed to predict insoluble and soluble dietary fiber using data sets expanded to include products with high fat and high sugar contents. The models predicted insoluble dietary fiber accurately with an SECV of 1.54% and an R(2) of 0.98 (AOAC determined range of 0-48.77%) and soluble dietary fiber less accurately with an SECV of 1.15% and an R(2) of 0.82 (AOAC determined range of 0-13.84%). Prediction of independent validation samples by the soluble fiber model resulted in a bias that may be related to the way the reference method treats samples with different soluble fiber constituents. The insoluble fiber model can be used to rapidly monitor insoluble dietary fiber in cereal products for nutrition labeling.     

Rapid determination of total cholesterol in homogenized milk

A rapid method that is amenable to automation has been developed for the determination of total cholesterol in homogenized milk. The milk sample is saponified in ethanolic KOH in the presence of an internal standard, cholestane. Cholesterol and the internal standard are then isolated by solid-phase extraction on a nonpolar adsorbent and eluted with organic solvent. The evaporated extract is derivatized and analyzed by capillary gas chromatography. Average recovery of cholesterol acetate added to milk prior to saponification was 95%. The average relative standard deviation for repeated analyses was 2%. The limit of detection for this method is 2 mg/100 g. Twenty samples can be analyzed by one analyst in a normal work day if the gas chromatograph is equipped with an autosampler. This method has been compared with a modified AOAC method for the determination of total cholesterol. At a confidence level of 95%, no difference was observed between the 2 methods.     

Improved method for measurement of dietary fiber as non-starch polysaccharides in plant foods

A method is described that allows rapid estimation of total, soluble, and insoluble dietary fiber as the non-starch polysaccharides (NSP) in plant foods. It is a modification of an earlier, more complex procedure. Starch is completely removed enzymatically, and NSP is measured as the sum of its constituent sugars released by acid hydrolysis. The sugars may, in turn, be measured by gas chromatography (GC), giving values for individual monosaccharides, or more rapidly by colorimetry. Both GC and colorimetry are suitable for routine measurement of total, soluble, and insoluble dietary fiber in cereals, fruits, and vegetables. Values obtained are not affected by food processing so the dietary fiber content of various processed foods and mixed diets can be calculated simply from knowing the amount in the raw materials. The additional information obtained by GC analysis is valuable in the interpretation of physiological studies and in epidemiology where disease is related to type and amount of dietary fiber.     

Inconsistent differences between neutral detergent fiber and total dietary fiber values of fruits and vegetables

A large number of fruits and vegetables were analyzed to determine levels of neutral detergent fiber (NDF) and total dietary fiber (TDF). The results showed that the TDF method is more precise than the NDF method. Further, the NDF values are significantly higher than the TDF values for apples and for miscellaneous fruits and vegetables, and significantly lower for stonefruit. For berryfruit, the differences between the NDF and TDF data are not significant. Also, a significant interaction between sample and method (except for berryfruit) indicated that, within groups, the (TDF-NDF) values vary so much that a "group difference" does not exist; consequently, figures from one method cannot be estimated from results of the other.     

Determination of total dietary fiber in foods and food products: collaborative study

A collaborative study was conducted to determine the total dietary fiber (TDF) content of food and food products, using a combination of enzymatic and gravimetric procedures. The method was basically the same as published earlier (J. Assoc. Off. Anal. Chem. (1984) 67, 1044-1052), with changes in the concentration of alcohol and buffers, time of incubation, sample preparation, and some explanatory notes, all with the intent of decreasing the coefficient of variation (CV) of the method. Duplicate blind samples of soy isolate, white wheat flour, rye bread, potatoes, rice, wheat bran, oats, corn bran, and whole wheat flour were analyzed by 9 collaborators. TDF was calculated as the weight of the residue minus the weight of protein and ash. CV values of the data from all laboratories for 7 of the samples ranged from 1.56 to 9.80%. The rice and soy isolate samples had CV values of 53.71% and 66.25%, respectively; however, each sample contained only about 1% TDF. The enzymatic-gravimetric method for determining TDF has been adopted official first action.     

Near-infrared diffuse reflectance spectroscopy for the analysis of poultry manures

The objective was to evaluate near-infrared diffuse reflectance spectroscopy (NIRS) for determining the composition of poultry manures. Poultry manure samples were obtained from a commercial testing laboratory along with conventionally determined analyte values for total N, NH(4)(+)-N, organic N (computed as total minus NH(4)(+)-N), minerals, and moisture. Samples were blended in a food blender and scanned in polyethylene bags on a FOSS-NIRSystems model 6500 scanning monochromator. Initial results indicated that changes had occurred in NH(4)(+)-N contents from the time of analysis, and samples were reanalyzed for NH(4)(+)-N. Using the new analyses, NIRS was able to accurately determine NH(4)(+)-N, organic N, total N, and moisture in 128 poultry manures. Results were more accurate when determinations were made on an "as is" as opposed to dry matter basis. Finally, results indicated that NIRS was not suitable for the determination of minerals (P, K, Ca, etc.) in poultry manures.     

Determination of total dietary fiber of intact cereal food products by near-infrared reflectance

Near-infrared reflectance spectra of cereal food products were acquired with a commercial dual-diode-array (Si, InGaAs) spectrometer customized to allow rapid acquisition of scans of intact breakfast cereals, snack foods, whole grains, and milled products. Substantial gains in the performance of multivariate calibration models generated from these data were obtained by a computational strategy that systematically analyzed the performance of various spectral windows. The calibration model based on 137 cereal food products determined the total dietary fiber (TDF) content of a test set of 45 intact diverse cereal food products with root-mean-squared error of cross-validation of between 1.8 and 2.0% TDF, relative to the laborious enzymatic-gravimetric reference method. The calibration performance is adequate to estimate TDF over the range of values found in diverse types of cereal food products (0.7-50.1%). The method requires no sample preparation and is relatively unaffected by specimen moisture content.     

Comparative contents of dietary fiber, total phenolics, and minerals in persimmons and apples

Dietary fibers, major phenolics, main minerals, and trace elements in persimmons and apples were analyzed and compared in order to choose a preferable fruit for an antiatherosclerotic diet. Fluorometry and atomic absorption spectrometry following microwave digestion were optimized for the determination of major phenolics and minerals. Total, soluble, and insoluble dietary fibers, total phenols, epicatechin, gallic and p-coumaric acids, and concentrations of Na, K, Mg, Ca, Fe, and Mn in whole persimmons, their pulps, and peels were significantly higher than in whole apples, pulps, and peels (P < 0.01-0.0025). Conversely, the contents of Cu and Zn were higher in apples than in persimmons. In persimmons and apples all of the above components were higher in their peels than in whole fruits and pulps. The relatively high contents of dietary fibers, total and major phenolics, main minerals, and trace elements make persimmon preferable for an antiatherosclerotic diet.     

Near-infrared reflectance model for the rapid prediction of total fat in cereal foods

AOAC method 996.01, used in cereal foods to determine total fat as defined by the U.S. Nutrition Labeling and Education Act (NLEA), is laborious and time-consuming and utilizes hazardous chemicals. Near-infrared (NIR) reflectance spectroscopy, a rapid and environmentally benign technique, was investigated as a potential method for the prediction of total fat using AOAC method 996.01 as the reference method. Near-infrared reflectance spectra (1104-2494 nm) of ground cereal products (n = 72) were obtained using a dispersive spectrometer, and total fat was determined according to AOAC method 996.01. Using multivariate analysis, a modified partial least-squares model was developed for total fat prediction. The model had a SECV of 1.12% (range = 0.5-43.2%) and a multiple coefficient of determination of 0.99. The model was tested with independent validation samples (n = 36); all samples were predicted within NLEA accuracy guidelines. The results indicate that NIR reflectance spectroscopy is an accurate means of determining the total fat content of diverse cereal products for nutrition labeling.     

Near-infrared imaging spectroscopy based on sugar absorption band for melons.

A method for visualizing the sugar content in the flesh of melons was developed. This method was based on the sugar absorption band in the near-infrared (NIR) region to avoid bias caused by the color information of a sample. NIR spectroscopic analysis revealed that each of the two second-derivative absorbances at 874 and 902 nm had a high correlation with the sugar content of melons. A high-resolution cooled charged couple device camera with band-pass filters, which included the above two wavelengths, was used to capture the spectral absorption image of a half-cut melon. A color distribution map of the sugar content on the surface of the melon was constructed by applying the NIR spectroscopy theory to each pixel of the acquired images.     

Near-infrared reflectance spectroscopy for predicting amino acids content in intact processed animal proteins

Near-infrared calibrations were developed for the instantaneous prediction of amino acids composition of processed animal proteins (PAPs). Two sample presentation modes were compared (ground vs intact) for demonstrating the viability of the analysis in the intact form, avoiding the need for milling. Modified partial least-squares (MPLS) equations for the prediction of amino acids in PAPs were developed using the same set of samples (N = 92 PAPs) analyzed in ground and intact form and in three cups differing in the optical window size. The standard error for cross validation (SECV) and the coefficient of determination (1-VR) values yielded with the calibrations developed using the samples analyzed in the intact form showed similar or even better accuracy than those obtained with finely ground samples. The excellent predictive ability (1-VR > 0.90; CV < 3.0%) obtained for the prediction of amino acids in intact processed animal proteins opens an enormous expectative for the on-line implementation of NIRS technology in the processing and marketing of these important protein feed ingredients, alleviating the costs and time associated with the routine quality controls.     

红茶感官品质及成分近红外光谱快速检测模型建立

以在发酵过程中小叶种工夫红茶为研究对象,分别建立了基于近红外光谱检测技术的感官品质评分和理化品质指标(茶黄素、茶红素、茶褐素、儿茶素和酚氨比)的定量分析模型。在模型建立过程中,探讨了特征变量优选方法对预测模型的影响。首先,对获取的近红外光谱数据进行标准正态变量变换法(standard normal Z transformation,SNV)预处理,进而采用联合区间偏最小二乘回归(synergy interval PLS,Si-PLS)、随机蛙跳算法(shuffled frog leaping algorithm,SFLA)、竞争性自适应权重取样法(competitiveadaptivereweightedsampling,CARS)和连续投影(successive projections algorithm,SPA),筛选出各品质指标的最优特征波长变量;最后基于优选波长分别建立各发酵品质指标的偏最小二乘法(partial least squares regression,PLS)线性预测模型和支持向量机(support vector regression,SVR)非线性预测模型。模型结果比较表明,Si、CARS、SFLA和SPA等变量筛选方法可有效压缩变量,以及进一步提高模型精度。非线性模型的预测均方根误差值(root-mean-square error of prediction,RMSEP)均明显小于PLS模型,相关性系数(correlation coefficient,R)和相对分析误差(relative percent deviation,RPD)均高于PLS模型。对于红茶发酵品质的检测上,非线性模型性能优于线性模型。感官品质、茶褐素和儿茶素的最优变量SVR预测模型的RPD值分别为3.923、3.234和5.462,酚氨比和茶红素模型的RPD值分别为2.815和2.223。除茶黄素的评价模型外(RPD为1.77),基于最优特征波长的各品质指标SVR模型的RPD值均大于2,表明模型具有极好的预测性能。研究结果为实现工夫红茶发酵品质的近红外光谱快速检测的实际应用奠定理论基础。     

Phenotypic divergence in vegetable amaranth for total antioxidant capacity,antioxidant profile,dietary fiber,nutritional and agronomic traits

A lot of variations in vegetable amaranth germplasm have been observed in Bangladesh. It has been used as a cheap source of antioxidants, nutrients, protein, and dietary fiber. But no efforts had not been taken to know the status of antioxidant content, polyphenol, flavonoid, antioxidant vitamins and minerals, dietary fiber, nutritional and agronomic traits. In this study, Forty-three vegetable amaranth genotypes were evaluated to determine the status of total antioxidant content, polyphenol, flavonoid, antioxidant vitamins and minerals, dietary fiber, nutritional and agronomic traits and the magnitude of genetic diversity based on the contribution of those traits for meaningful grouping and proper utilization in future breeding program. The experiment was carried out in an open experimental field at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Bangladesh in a randomized complete block design with three replications. Multivariate (Principal component and cluster) analysis was done using numerical taxonomic techniques of Sneath, & Sokal. Four principal components contributed 98.61% of the variation. Biological yield and total antioxidant content was strongly associated with their related all agronomic traits. Total flavonoid content had a higher contribution to total antioxidant capacity compared to vitamin and mineral antioxidants. Contribution of antioxidant profile and agronomic traits was the highest in diversity of vegetable amaranth. Both high and low yielding genotypes had a high antioxidant profile. Therefore, high yielding genotypes (From cluster VI) could be used directly as high antioxidant profile varieties and low yielding genotypes as a source of donor parents in hybridization program. Cluster analysis grouped the genotypes into six clusters. The diverse genotypes in different clusters were identified. Genotypes with desirable genes of one cluster hybridized with promising genotypes of other diverge clusters could facilitate the accumulation of favorable genes in hybrids.

Abbreviations: PCA: principal component analysis; PC: principal component; dw: dry weight; TFC: total flavonoid content; TAC: total antioxidant capacity; TPC: total polyphenol content; K: potassium; Ca: calcium; Mg: magnesium; Fe: iron; Mn: manganese; Cu: copper; Zn: zinc     

Determination of insoluble, soluble, and total dietary fiber in foods and food products: interlaboratory study

A collaborative study was conducted to determine the insoluble dietary fiber (IDF), soluble dietary fiber (SDF), and total dietary fiber (TDF) content of food and food products by using a combination of enzymatic and gravimetric procedures. The method was basically the same as that developed for TDF only, which was adopted official final action by AOAC, except for changing the concentration of buffer and base and substituting hydrochloric acid for phosphoric acid. These changes were made to improve the robustness of the method. Duplicate blind samples of soy isolate, white wheat flour, rye bread, potatoes, rice, corn bran, oats, Fabulous Fiber, wheat bran, and a high fiber cereal were analyzed by 13 collaborators. Dietary fiber values (IDF, SDF, and TDF) were calculated as the weight of residue minus the weight of protein and ash. The coefficients of variation (CVs) of both the independent TDF determination and the sum of IDF and SDF were better than 15 and 18%, respectively, with the exception of rice and soy isolate. These 2 foods, however, contained only about 1% TDF. The CVs of the IDF were equally good, except for Fabulous Fiber, for which filtration problems occurred. The CVs for the SDF were somewhat high, but these products had very low SDF content. There was excellent agreement between the TDF determined independently and the TDF determined by summing the IDF and SDF. The method for separate determination of IDF and SDF requires further study. The modifications (changes in concentration of buffer and base and the use of hydrochloric acid instead of phosphoric acid) to the official final action method for TDF have been adopted.     

Determination of total gossypol in cottonseed and cottonseed meals by derivative UV spectrophotometry

A new method for the determination of total gossypol in cottonseed and cottonseed meals has been developed. The method involves oxalic acid hydrolysis of the bound gossypol in a methyl ethyl ketone-water azeotrope, partitioning the liberated gossypol into chloroform, and quantification by 2nd derivative UV spectrophotometry. The 2nd derivative transformation and measurement of the conventional analytical band around 300 nm permits direct quantification of all compounds containing naphthalene nuclei; chromogenic reaction is not required. The method was tested at concentration levels of total gossypol normally expected for cottonseed and cottonseed meal. Precision and accuracy data suggested an overall relative standard deviation of 4.0% and an overall recovery of 89.5%. Although results for cottonseed and solvent-extracted cottonseed meal analyses were comparable to those obtained by use of American Oil Chemists' Society methods, results were lower for screw-pressed meals. The lower results were attributed to the partial conversion of gossypol, during the cooking process of these meals, to compounds that differ in composition and structure from gossypol and which react with aniline to give false readings.