酶促挤压对藜麦理化性质的影响

为探究耐高温α-淀粉酶在藜麦挤压过程中对其理化性质、酚类物质和抗氧化能力的影响,作者采用了5种不同质量分数的酶溶液对藜麦进行挤压处理。结果表明,相比于传统挤压处理的样品,经酶促挤压处理的样品中水溶性指数上升、吸水性指数下降、峰值黏度下降、粒径减小;同时酶促挤压可显著提高样品中的总酚、黄酮质量分数以及抗氧化活性。作者用高效液相色谱法研究了样品处理前后酚酸的变化,结果表明高温α-淀粉酶可显著提高样品中芦丁、咖啡酸、没食子酸的质量分数。综上所述,耐高温α-淀粉酶的加入改善了传统挤压对藜麦理化特性及酚类物质的影响,该研究结果为藜麦深加工提供了参考。     

Determination of Antioxidant Properties of Fruit Juice by Partial Least Squares and Principal Component Regression

The multivariate calibration methods—principal component regression and partial least squares—were employed for the prediction of antioxidant capacities of fruit juices. High-performance liquid chromatography and spectrophotometric approaches were used to determine the antioxidant capacities of fruit juices. The importance of calibration design was investigated by calculating the prediction and validation errors. The influences of using independent validation sets were emphasized. Calibration design is shown to have major effect on principal component regression and partial least squares errors. The models developed on the basis of the mean-centered data were able to predict the total antioxidant activity with a precision comparable to that of the reference [2,2-azino-di-(3-ethylbenzothialozine-sulfonic acid)] method. The partial least squares model seems preferable because of its predictive and describing abilities and good interpretability of the contribution of compounds to the antioxidant capacity. The contribution of individual phenolic compounds to the antioxidant capacity was identified by high-performance liquid chromatography.     

Partial Least Squares Analysis of the Relationship Between Chemical Composition and Phenolic Compounds in Blueberry Cultivars

Blueberries (Vaccinium spp.), one of the most widely consumed fruits worldwide, are rich in nutrients and exhibit antioxidant activity. In this study, the partial least squares and principal component analyses were used and the chemical composition and mineral and phenolic compound contents of blueberry cultivars suited to northern China were determined. Blueberries growing in northern China contain a rich variety of biologically active compounds at high concentrations and have high nutritive mineral values. In general, the chemical composition data of the blueberry cultivars examined were similar to those obtained by the US Department of Agriculture (USDA). However, the mineral content data showed iron and potassium concentrations that were slightly higher than those found by the USDA. In addition, the iron concentrations were lower than those found in the literature for Brazilian cultivars. The zinc, magnesium, and vitamin C in blueberries may promote the growth and accumulation of total phenols and anthocyanins, while total acid, iron, and potassium have opposite effects. Total phenols correlated positively with anthocyanins. Differences in protein, total carbohydrate, potassium, and sodium between cultivars could affect total phenol and anthocyanin contents. Adjusting the total acid concentration and reducing the sugar and mineral contents may affect anthocyanin content in blueberries. These changes may improve the nutritional value and fruit quality of blueberries.     

基于PLSR分析樱桃酒呈味物质与感官属性之间的相关性

以6种不同厂家生产的樱桃酒为研究对象,进行感官评价并利用高效液相色谱法鉴定出樱桃酒样品的33种特征呈味物质,并进行了主成分分析和聚类分析。结果显示,相同产地的樱桃酒聚集在一起成一类,不同产地的樱桃酒明显区分开来。通过偏最小二乘法对不同产地樱桃酒中特征呈味物质与感官属性之间的相关性进行研究,结果发现甜味与葡萄糖、蔗糖、果糖呈现出显著正相关;涩味与丝氨酸、苯丙氨酸呈显著正相关;苦味与咖啡酸、谷氨、丝氨酸、甘氨酸、苏氨酸、丙氨酸、缬氨酸、蛋氨酸、苯丙氨酸、异亮氨酸、亮氨酸、赖氨酸呈现显著正相关。     

香气活度值法结合PLSR用于梨酒特征香气物质筛选与鉴定

采用固相微萃取-气相色谱-质谱对市售3种梨酒香气物质进行分离鉴定,共检出43种挥发性成分,其中醇类16种、酯类15种、醛类4种、酮类2种、酚类1种、酸类3种和其他化合物2种。结合香气活度值(odor activity value,OAV)和偏最小二乘回归(partial least squares regression,PLSR)确定梨酒特征香气物质并推断其对梨酒香气的贡献程度。OAV结果表明:梨酒特征香气物质主要为异丁醇、1-辛醇、1-壬醇、苯乙醇、丁酸乙酯、3-甲基丁酸乙酯、乙酸异戊酯、己酸乙酯、辛酸乙酯、β-大马士酮、丁香酚。建立6个感官属性(发酵香、酸香、果香、花香、甜香、清香)与43种香气物质的PLSR模型表明,苯甲醇、正丁醇、丁二酸二乙酯的OAV小于1,但对梨酒的香气有贡献,经OAV确定的梨酒特征香气物质与发酵香和甜香属性具有很好的相关性,而在清香、酸香、果香和花香上的相关性不明显。     

Physiochemical Properties and Probiotic Survivability of Symbiotic Corn‐Based Yogurt‐Like Product

Corn is a major grain produced in northern China. Corn‐based functional food products are very limited. In this study, a symbiotic corn‐based yogurt‐like product was developed. Corn milk was prepared through grinding, extrusion and milling, and hydration processes. Corn extrudate was prepared under the optimized conditions of corn flour particle size <180 μm, moisture content of 15% and extrusion temperature at 130 °C. The corn milk was prepared from 8% corn extrudate suspension and then milled twice with 0.1% glyceryl monostearate and 0.1% sucrose ester as emulsifiers. The corn milk was mixed with sugar (5%), glucose (2%), soy protein isolate (0.75%), inulin (1%), polymerized whey protein (0.3%) and xanthan gum (0.09%) as thickening agents. The mixture was fermented at 35 °C for 6 h using a probiotic starter culture containing L. plantarum. Chemical composition (%) of the symbiotic corn‐based yogurt‐like product was: total solids (17.13 ± 0.31), protein (1.12 ± 0.03), fat (0.30 ± 0.05), carbohydrates (15.14 ± 0.19), and ash (0.16 ± 0.02), respectively. pH value of this symbiotic product decreased from 4.50 ± 0.03 to 3.88 ± 0.13 and the population of L. plantarum declined from 7.8 ± 0.09 to 7.1 ± 0.14 log CFU/mL during storage at 4 °C. SDS‐PAGE analysis showed that there were no changes in protein profile during storage. Texture and consistency were also stable during the period of this study. It can be concluded that a set‐type corn‐based symbiotic yogurt‐like product with good texture and stability was successfully developed that would be a good alternative to the dairy yogurt.     

The Effect of Cooking Water Composition on Textural and Cooking Properties of Spaghetti

The effect of cooking water on both textural and cooking properties of spaghetti was investigated for spaghetti samples, which differ in protein content. The samples were analysed after cooking in deionised, laboratory tap water, deionised water with 2.5% salt and deionised water with 5.0% salt. Brands A, B, and C were usual durum wheat spaghetti and brand D was spaghetti enriched with bran. Regardless of the cooking water used, brand D had higher hardness and lower adhesiveness than other spaghetti samples and required longer cooking time to achieve optimum cooking. It was found that samples cooked deionised water had lower hardness and adhesiveness values as compared to samples cooked in salty water. It can be concluded that a certain amount of salt in the cooking water improves textural characteristics of cooked pasta.     

基于主成分分析和偏最小二乘法的蒸煮大豆食味品质评价

通过建立主成分分析结合偏最小二乘法(PLS)评价蒸煮大豆食味品质。以黑龙江45个大豆品种的理化指标、浸泡后的吸水率和膨胀率为自变量,以蒸煮后的硬度、咀嚼性和感官评分为因变量,应用偏最小二乘法判别模型中各变量的相关系数和变量投影重要性,筛选影响蒸煮大豆食味品质的主要因素并进行主成分分析。结果表明:通过PLS筛选出大豆钙含量、伴大豆球蛋白(7S球蛋白)、可溶性糖含量和膨胀率对蒸煮后大豆质构特性有主要影响。主成分分析检测得到4个主成分,累计贡献率达73.374%,可较好地反映蒸煮大豆食味品质信息。根据各主成分的贡献率得出蒸煮大豆的硬度、咀嚼性及7S球蛋白、11S/7S、钙含量等为蒸煮大豆食味品质的主要影响因子。利用主成分综合得分模型对不同品种的蒸煮大豆食味品质进行综合评分,筛选出5种适宜蒸煮加工的大豆品种,即:黑农85、合丰55、JD149、绥农42和东农251。     

Trout‐Skin Gelatin‐Based Edible Films Containing Phenolic Antioxidants: Effect on Physical Properties and Oxidative Stability of Cod‐Liver Oil Model Food

Abstract: Trout‐skin (Oncorhynchus mykiss) gelatin‐based films containing antioxidants (epigallocatechin gallate (EGCG), 50 and 250 ppm w/w) and green tea powder (1% and 20% w/w of gelatin) were tested for tensile strength, elastic modulus, and elongation, and oxygen and water vapor transmission rates, in vitro antioxidant activity using the DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) assay and effect on stabilizing cod‐liver oil held under mild thermal abuse conditions. Cod‐liver oil overlaid with films was stored at 40 °C for 20 d and analyzed for peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). Antioxidant activity was retained in films containing green tea powder, but was reduced (P < 0.05) in EGCG films (20 d, 23 °C). Water vapor transmission rate of the films incorporated with antioxidants did not change significantly (P > 0.05), but the oxygen transmission rate for films with 50 ppm EGCG and 20% green tea powder was significant (P < 0.05). Other physical properties varied with antioxidant incorporation. The TBARS and PV of control oil increased from 0.05 ± 0.01 to 4.71 ± 0.30 g MDA/kg oil and from 3.6 ± 0.2 to 178.3 ± 24.5 millieq peroxides/kg oil, respectively, after 20 d. For cod‐liver oil covered with control or antioxidant‐containing films, TBARS remained below 0.37 g MDA/kg oil and PV below 7 millieq peroxides/kg oil. Incorporation of antioxidants to the films did not reduce oil oxidation (P > 0.05) at the levels tested and this was confirmed by activation energy calculations. The rate of oil oxidation was more dependent upon the inherent oxygen barrier property of the films than the presence of antioxidants. Practical Application: This research has the potential to enhance the utilization of fish skins, a valuable food processing by‐product, as edible films with natural antioxidants to extend the shelf life of foods. The film physical properties and barrier to oxygen and water are investigated.     

Gluten‐Free Precooked Rice‐Yellow Pea Pasta: Effect of Extrusion‐Cooking Conditions on Phenolic Acids Composition,Selected Properties and Microstructure

Rice/yellow pea flour blend (2/1 ratio) was used to produce gluten‐free precooked pasta using a single‐screw modified extrusion‐cooker TS‐45. The effect of moisture content (28%, 30%, and 32%) and screw speed (60, 80, and 100 rpm) on some quality parameters was assessed. The phenolic acids profile and selected pasta properties were tested, like pasting properties, water absorption capacity, cooking loss, texture characteristics, microstructure, and sensory overall acceptability. Results indicated that dough moisture content influenced all tested quality parameters of precooked pasta except firmness. Screw speed showed an effect only on some quality parameters. The extrusion‐cooking process at 30% of dough moisture with 80 rpm is appropriate to obtain rice‐yellow pea precooked pasta with high content of phenolics and adequate quality. These pasta products exhibited firm texture, low stickiness, and regular and compact interne structure confirmed by high score in sensory overall acceptability.     

玉米挤压工艺条件的优化及其理化特性的研究

以玉米籽粒为原料,以膨化度为指标,在单因素试验基础上,采用响应面分析法研究挤压工艺条件对玉米籽粒膨化特性的影响,并分析其主要理化特性.结果表明,回归方程能较好地预测玉米膨化度随挤压工艺参数变化的规律,玉米挤压膨化的最佳工艺条件为物料粒度60目,物料含水量24.5％,挤压温度164℃,转速400r/min,膨化度3.42％.玉米经挤压后还原糖、可溶性膳食纤维、吸水性指数、水溶性指数、糊化度分别提高361.54％、134.38％、80.20％、186.4％和794.12％,淀粉、不溶性膳食纤维分别降低26.03％和36.67％,蛋白质含量基本不变,玉米的理化特性得到有效改善.     

基于挥发性成分定量预测风味茶油掺浸出茶油的偏最小二乘回归模型的建立

为解决在压榨风味茶油掺浸出茶油的定量预测问题,本文设计高/低两个掺伪梯度,基于挥发性成分,运用Python语言构建定量预测压榨风味（原香和浓香）茶油掺浸出茶油的偏最小二乘回归（PLSR）模型。研究结果表明,高掺伪梯度下压榨原/浓香茶油样本的定量鉴别PLSR模型的平均R2值均达到了0.998,平均RMSE值为1.127/1.166,大部分样本的相对误差集中在0~0.1之间;低掺伪梯度下压榨原/浓香茶油样本的定量鉴别PLSR模型的平均R2值达到了0.956/0.999,平均RMSE值为0.592/0.094,大部分样本的相对误差集中在0~0.15/0~0.02之间。本文所构建的PLSR模型定量鉴别压榨风味茶油掺浸出茶油的准确率较高,压榨浓香茶油掺浸出茶油的定量鉴别效果要好于压榨原香茶油。     

PGPR菌剂对植烟土壤理化性状及phoD基因群落结构的影响

为探明PGPR菌剂对土壤磷素循环的微生物调控机制,以凉山州会理市的植烟田为研究对象,采集烤烟成熟期耕层土壤,通过化学分析和高通量测序技术,对细菌型、放线菌型和真菌型3种PGPR菌剂处理土壤的理化性质、磷酸酶活性及phoD基因群落组成进行了分析。结果表明,与常规施肥相比,施用3种PGPR菌剂均能显著提高土壤有机碳、全氮、有效磷和速效钾含量,放线菌型PGPR菌剂能显著提升土壤的磷酸酶活性。PGPR菌剂能提高植烟土壤phoD基因群落的多样性,门水平优势菌群为放线菌门（Actinobacteria）、变形菌门（Proteobacteria）和蓝菌门（Cyanobacteria）等,属水平优势菌属为链霉菌属（Streptomyces）、无枝酸菌属（Amycolatopsis）和慢生根瘤菌属（Bradyrhizobium）等。冗余分析显示,速效钾、pH、速效磷等环境因子是影响植烟土壤phoD基因群落结构的主要因子。综上所述,PGPR菌剂能显著改善植烟土壤养分状况,提高土壤磷酸酶活性,改变烤烟耕层phoD基因群落结构。     

The Effect of Wheat and Maize Flours Properties on the Expansion Mechanism During Extrusion Cooking

The expansion mechanism in the extrusion cooking process was investigated during maize and wheat flours processing in a twin-screw extruder. An experimental study of extrusion process was carried out at constant moisture and specific mechanical energy. The expansion phenomenon which consists in a growth phase followed by a shrinkage phase was observed through an image processing method and analyzed by use of classical expansion indices: sectional, longitudinal and volumetric expansion indices. It was found that the maximum expansion is obtained with maize flour and that the difference in composition between maize and wheat flours has an impact on the expansion mechanism. Image analysis method enabled to obtain an instantaneous measurement of the growth and shrinkage parameters and appeared as useful tool to characterise expansion in function of extrusion conditions. A model based on the bubble growth in a viscous medium was proposed to analyze this expansion phenomenon. It enabled to study the evolution of expansion rates in function of the characteristic times of the problem: the bubble formation characteristic time and the maximum expansion time in both radial and longitudinal directions.     

挤压组织化对芝麻蛋白理化性质及结构的影响

以亚临界芝麻蛋白粉为主要原料,利用双螺杆挤压技术研究挤压组织化处理对蛋白原料理化性质及结构的影响,探讨组织化蛋白形成机理。结果表明,挤压组织化对蛋白原料理化性质及结构都造成了一定的影响。挤压后蛋白原料持水性增加了14.16%,吸油性减少了14.52%,蛋白消化率增加了11.18%,游离巯基含量减少了11.55%,氨基酸各组分含量均有一定损失,挤压组织化过程中没有新的肽键生成,有大量的二硫键生成,挤压得到的组织化蛋白结构主要是由二硫键和非共价键共同作用维持。挤压组织化并未完全破坏蛋白质二级结构,只有部分不稳定的α-螺旋和无规则卷曲向相对稳定的β-折叠和β-转角转化,蛋白原料由无序变为有序,并产生了大量的纤维结构,本文为后续深入开展组织化蛋白形成机理研究、开发组织化芝麻蛋白产品提供理论基础。     

Gluten‐Free Snacks Using Plantain–Chickpea and Maize Blend: Chemical Composition,Starch Digestibility,and Predicted Glycemic Index

An increase in celiac consumers has caused an increasing interest to develop good quality gluten‐free food products with high nutritional value. Snack foods are consumed worldwide and have become a normal part of the eating habits of the celiac population making them a target to improve their nutritive value. Extrusion and deep‐frying of unripe plantain, chickpea, and maize flours blends produced gluten‐free snacks with high dietary fiber contents (13.7–18.2 g/100 g) and low predicted glycemic index (28 to 35). The gluten‐free snacks presented lower fat content (12.7 to 13.6 g/100 g) than those reported in similar commercial snacks. The snack with the highest unripe plantain flour showed higher slowly digestible starch (11.6 and 13.4 g/100 g) than its counterpart with the highest chickpea flour level (6 g/100 g). The overall acceptability of the gluten‐free snacks was similar to that chili‐flavored commercial snack. It was possible to develop gluten‐free snacks with high dietary fiber content and low predicted glycemic index with the blend of the 3 flours, and these gluten‐free snacks may also be useful as an alternative to reduce excess weight and obesity problems in the general population and celiac community.