灭菌对罐装绿茶水品质的影响

本文在分析高温灭菌前后绿茶水中主要品质成分及感官品质变化的基础上,进一步探讨了L－抗坏血酸对茶汤中儿茶素、氨基酸组分及色泽的保护效果。结果表明：经高温灭菌后,绿茶水中茶多酚氨基酸含量下降,咖啡碱则相对稳定,茶汤色泽黄变,香味熟钝;低级原料茶汤品质劣变程度较轻。添加L－抗坏酸对儿茶素、氨基酸组分没有明显的保护作用,但能达到护色效果。     

冷藏和冰藏条件下大菱鲆品质变化与蛋白质氧化相关性

为探明大菱鲆在贮藏过程中肌肉品质变化与蛋白质氧化的关系,研究了4℃冷藏和0℃冰藏条件下大菱鲆鱼肉蛋白质氧化指标和品质指标随贮藏时间的变化,并进行了相关性分析。结果显示,随着贮藏时间的延长,2组样品的持水性、表面疏水性以及羰基与二硫键含量呈上升趋势,而感官评分、质构指标和总巯基含量均呈下降趋势。综合各项指标变化,冷藏和冰藏过程中大菱鲆鱼肉品质劣化程度随蛋白质氧化逐渐增加,且冷藏组品质劣化和蛋白质氧化的速度明显快于冰藏组;在相同贮藏条件下,大菱鲆鱼肉蛋白质氧化程度越高,其品质越差。通过相关性分析发现,在冷藏和冰藏条件下大菱鲆鱼肉蛋白质氧化指标与品质指标之间存在良好的相关性,贮藏过程中大菱鲆鱼肉品质变化与蛋白质氧化密切相关。     

不同保鲜剂对碧螺春茶保鲜效果影响的研究

以苏州碧螺春茶为原料,设计了16种不同保鲜剂,经过一定条件贮藏老化后,考察了它们对于碧螺春茶的保鲜效果,结果表明：处理9(硅胶和抗坏血酸钠系列)及处理11(焦亚硫酸钠和抗坏血酸钠系列)保鲜效果最好,处理1(铁粉和氯化钠系列)、处理6(铁粉、氯化亚铁、碳酸氢钠、反丁烯二酸和沸石系列)、处理12(细孔硅胶)、处理14(活性干燥剂)保鲜效果较好,并对感观品质各特点与生化成分含量的相关性做了分析研究。     

基于乙醇含量的双孢菇采后品质劣变程度预测模型

呼吸作用是果蔬采收后最基本的生理过程,在很大程度上决定着果蔬的品质变化,不彻底的氧化而产生的乙醛、乙醇等还原性物质将会对菇体细胞的正常代谢造成影响。通过研究不同温度下双孢菇贮藏期间乙醇含量(Q)的变化规律及其与感官评价结果之间的相关关系,以此为基础建立了双孢菇品质劣变预测模型。研究结果表明:双孢菇在不同温度贮藏期间乙醇含量与感官评价结果显著相关(皮尔逊相关系数r分别是0.964 6、0.907 6、0.992 9、0.980 8)。根据双孢蘑菇乙醇含量随时间变化的数据,通过曲线拟合结合Arrhenius方程确定基于乙醇含量值的双孢菇品质劣变程度预测模型为Q=Q0exp[1.5×109exp(-6 743T)t]。将Q值的预测值和实测值进行比较,平均误差小于10%,验证了基于乙醇含量建立的预测模型可预测双孢菇品质劣变程度。     

热处理联合不同包装对鲜切马铃薯贮藏品质的影响

为解决鲜切马铃薯贮藏品质劣变快、货架期短的问题,本研究探讨45℃热处理3 min联合真空包装和30%CO2+70%N2气调包装对鲜切马铃薯贮藏品质的影响。结果表明：热处理联合气调包装可延缓鲜切马铃薯呼吸速率的上升,显著抑制丙二醛（malondialdehyde,MDA）含量上升及苯丙氨酸解氨酶（phenylalanine ammonia-lyase,PAL）、过氧化物酶（peroxidase,POD）、多酚氧化酶（polyphenol oxidase,PPO）活力（P<0.05）,有效维持总酚、抗坏血酸（ascorbic acid,AsA）、可溶性固形物含量（soluble solids content,SSC）和淀粉含量,抑制细菌菌落总数的增长,保持马铃薯原有挥发性风味和感官品质。综上,热处理联合气调包装可以使鲜切马铃薯保持较好的感官和营养品质,抑制微生物生长以及褐变酶活性,从而延长鲜切马铃薯货架期。     

海芦笋营养价值及其采后品质变化

以评价海芦笋的可食性及延缓其采后品质劣变为目标;测定了海芦笋的营养成分及微量有害元素;以感官质量、抗坏血酸、粗纤维和β-胡萝卜素含量为指标,研究海芦笋在20、4℃及真空预冷后4℃贮藏过程中的品质变化.结果表明,海芦笋含有较丰富的营养成分,而微量有害元素的含量都在国家标准限量范围内,符合食品卫生标准;海芦笋在20℃条件下只能贮藏8d左右.而低温贮藏能有效地延缓海芦笋采后品质劣变;经真空预冷后再冷藏,海芦笋的货架期可延长至30d以上.     

北京油鸡肉4 ℃贮藏过程中的品质及风味变化

北京油鸡是我国珍贵地方品种,为了解其鸡胸肉在4 ℃真空包装冷藏过程中的风味及品质变化规律,测定 其在贮藏过程中的挥发性盐基氮含量、菌落总数、感官评分、硫代巴比妥酸反应物值、总脂肪酸、肌苷酸及其他三 磷酸腺苷代谢物含量的变化,并利用电子鼻技术测定其在贮藏过程中的挥发性风味整体变化,与感官评分建立回归 方程。结果表明：综合各项理化、微生物及感官指标,真空包装北京油鸡鸡胸肉在4 ℃冷藏过程中的贮藏期为6 d; 脂肪氧化、不饱和脂肪酸和鲜味核苷酸的含量影响其贮藏过程中风味的劣变,并且利用电子鼻检测技术可以有效预 测其品质变化。     

5种精制食用油在煎炸薯条过程中的品质变化

以大豆油、菜籽油、棕榈液油、棉籽油和煎炸调和油为研究对象,以薯条为煎炸原料,通过研究5种精制食用油在高温煎炸过程中理化指标的变化,从而反映出不同精制食用油在煎炸过程中品质的变化。结果表明:色泽可以作为一个最直观的指标反映食用油的煎炸程度;用酸值来评价煎炸油的品质具有滞后性和多变性;过氧化值的高低并不能完全反映油脂的煎炸程度,仅可作为判断食用油煎炸品质的参考指标;羰基值随着煎炸时间的延长整体呈线性正相关趋势,说明羰基值是一个判断煎炸油热劣变程度的灵敏指标;5种精制食用油一旦经过煎炸,氧化诱导时间迅速缩短,与油脂的煎炸程度没有很好的相关性,因此氧化诱导时间不能作为评价油脂煎炸品质的可靠指标;极性组分的含量是评价煎炸油热劣变程度的可靠手段之一。在煎炸过程中,棕榈液油的煎炸稳定性明显高于其他4种食用油。     

不同贮藏方式对鲜切大白菜食用品质的影响

为探究不同贮藏方式对于鲜切大白菜食用品质的影响,研究采用不同包装及贮藏温度对鲜切大白菜进行处理,通过测定其感官品质、抗坏血酸、可溶性蛋白质、可溶性固形物及亚硝酸盐含量的变化,探究不同贮藏方式对鲜切大白菜食用品质的影响。结果表明：两种冷藏（4±1℃）条件下（即冷藏与冷藏PE）鲜切白菜的感官品质均显著优于两种室温（18±2℃）条件（即室温与室温PE）（P≤0．05）,且两种冷藏条件下可明显延缓抗坏血酸、可溶性蛋白质、可溶性固形物含量的下降,抑制亚硝酸盐含量的升高。其中,以冷藏PE贮藏方式对保持鲜切白菜的食用品质效果最佳。     

冻融次数对藏羊肉品质特性的影响

为研究反复冻融次数对冷藏藏羊肉品质特性的影响。本文以欧拉藏羊肉为研究对象,经反复冻融0、1、3、5次后置于4 ℃条件下冷藏1、3、5、7 d,测定其营养品质、食用品质、质构以及脂质氧化程度。研究结果显示,随着冻融次数的增加,藏羊肉营养品质明显降低,表现为水分含量和蛋白质含量显著下降（P < 0.05）;藏羊肉食用品质整体呈显著下降变化,尤其在冻融循环5次后,肉色稳定性及保水性均呈显著下降变化（P < 0.05）,嫩度略有下降但变化不大,且肌肉硬度及咀嚼性整体呈下降变化,黏度、弹性和胶着性均呈上升变化;过氧化值（POV）和硫代巴比妥酸值（TBARS）均在冻融循环5次后达到最大值（P < 0.05）,说明脂肪氧化程度随冻融次数增加而加重;同时,冷藏时间的延长也会进一步加剧肌肉品质的劣变,且冻融循环次数越多劣变越严重。可见,冻融循环次数的增多对肌肉品质有较大影响,在肉类实际生产加工和运输过程中应尽量避免反复冻融现象的发生。     

Multispectral Imaging for Plant Food Quality Analysis and Visualization

The multispectral imaging technique is considered a reformation of hyperspectral imaging. It can be employed to noninvasively and rapidly evaluate food quality. Even though several imaging or sensor‐based techniques have been conducted for the quality assessment of various food products, the rise of multispectral imaging has been more promising. This paper presents a comprehensive review of the use of the multispectral sensor in the quality assessment of plant foods (such as cereals, legumes, tubers, fruits, and vegetables). Different quality parameters (such as physicochemical and microbiological aspects) of plant‐based foods that were determined and visualized by the combination of modeling methods and feature wavelength selection approaches are summarized. Based on the literature, the most frequently used wavelength selection methods are the successive projection algorithm (SPA) and the regression coefficient (RC). The most effective models developed for analyzing plant food products are the partial least squares regression (PLSR), least square support vector machine (LS‐SVM), support vector machine (SVM), partial least squares discriminant analysis (PLSDA), and multiple linear regression (MLR). This article concludes with a discussion of challenges, potential uses, and future trends of this flourishing technique that is now also being applied to plant foods.     

POSTMORTEM BIOCHEMICAL AND TEXTURAL CHANGES IN THE ADDUCTOR MUSCLE OF CATARINA SCALLOP STORED AT 0C

Postmortem characteristics of the adductor muscle of the Catarina scallop were evaluated for biochemical, chemical and textural changes during a 15‐day storage period in ice (0C). K‐value, pH, nitrogen of trimethylamine (TMA‐N), nitrogen of total volatile bases (TVB‐N), water‐holding capacity (WHC), color and texture changes were monitored. K value increased linearly from an initial value of 20.5 to 68.5% at day 15. Spoilage indicators TVB‐N and TMA‐N (mg/100 g) increased from 13.5 and 2.6 to 21.4 and 3.4, respectively. However, they remained below critical limits, suggesting low microbial activity. In contrast, texture, pH, WHC, and color were not affected. Overall results indicated that the quality of iced Catarina scallop adductor muscle packed in ice was maintained over a period of 15 days.     

国内水飞蓟资源利用现状与展望

从产业化的角度，本着资源高效综合利用的原则，对水飞蓟植物资源引种国内后种籽的主要化学成分及利用价值进行了概述，对其利用现状及存在问题进行了分析，针对目前利用中存在的问题从技术角度提出了几点建议，并对共发展趋势进行了预测和展望。     

A RESEARCH NOTE: STUDY ON THE QUALITY OF PACHARÁN BY SENSORY EVALUATION

Pachardn is a traditional drink of Navarra, Spain. This spirit is an alcoholic drink which ranges from intense pink to red in color and whose base is sloe (Primus spinosa, L.) flavored with, the essential oils of aniseed and sugar. Sensory analysis was performed using samples from twenty-one different brands of commercial pachardn. Statistical techniques employed were formations of a linear correlation matrix, followed by factor analysis and multiple linear regression. Factor analysis permitted reduction of the sensory variables examined (color, aroma quality, flavor quality, sweetness, acidity and overall impression) to two factor variables (“flavor and aroma” and “color”). The position of the brands with respect to these two factors indicate the necessary changes to improve pachardn quality. The factors “flavor and aroma” had the chief direct effect on Overall Impression.     

运用数理统计与模糊数学方法改进绿豆糕的产品品质

本文首先考虑从市售绿豆糕中优选出在现行生产状况下的最佳产品,以此产品的工艺配方作为我们研究改进的起点,再运用正交试验法进行探索性改进实验,得出更优的工艺与配方,并应用模糊数学方法综合评判绿豆糕产品的感官质量,然后运用回归分析方法对主要因素进行分析,从而控制产品的质量.     

基于多元统计方法进行水牛乳掺水定量鉴别

采用常规方法测定不同掺水体积比例的水牛乳掺伪样的7 个主要品质指标,并基于这些指标参数采用单因素方差分析、主成分分析和多元逐步线性回归法,对不同掺水量的水牛乳进行定量鉴别,旨在寻求一种能有效监控水牛乳掺水的快速定量鉴别方法。利用单因素方差分析不同掺伪样的7 个重要理化指标的差异性,分析结果表明,水牛乳掺水的最低检出限为7%。主成分分析中,第1主成分贡献率达到85.464%,已包含样本的大部分信息,主成分1得分与掺水量存在显著的线性关系。通过多元逐步线性回归法建立了4 个定量模型方程,其相关系数R2分别为0.965、0.982、0.986、0.989,平均绝对误差分别为－0.23%、－2.40%、0.23%、1.28%,可实现水牛乳掺水的定量鉴别。     

Prediction of storage quality of fresh‐cut green peppers using artificial neural network

To extend the shelf‐life of fresh‐cut fruits and vegetables, it is essential to develop models that can accurately predict their storage quality. In view of this, an artificial neural network (ANN) model based on back propagation (BP) algorithm was developed to predict the storage quality (degree of yellowness, water loss, textural firmness and vitamin C content) of fresh‐cut green peppers. The prediction accuracy of ANN was compared with that of multiple linear regression‐based models. The root mean square error (RMSE), mean absolute error (MAE), sum of squared residuals (SSR) and standard error of prediction (SEP) were used as comparison parameters. The results showed that the accuracy and goodness of fit of the storage quality parameters predicted by ANN were better than those predicted by multiple linear regression‐based models. The RMSE, MAE, SSR and SEP values obtained from the former were much lower than those obtained from the latter.     

BIOCHEMICAL PROPERTIES OF ACTOMYOSIN AND EXPRESSIBLE MOISTURE OF FROZEN STORED ADDUCTOR MUSCLES OF PATAGONIAN SCALLOP (ZYGOCHLAMYS PATAGONICA)

The biochemical properties of actomyosin and the expressible moisture of frozen stored adductor muscles of scallop (Zygochlamys patagonica) were investigated. After freezing (zero time of storage) both the enzymatic activity and the reduced viscosity of actomyosin remained unchanged with respect to those corresponding to actomyosin from unfrozen muscles. Both parameters significantly decreased (P < 0.01) at 4 months of frozen storage and thereafter gradually decreased. No significant differences (P > 0.01) were observed in the relative percentages of myosin, actin, and in the myosin/actin ratio up to 4 months of storage. Thereafter myosin significantly decreased (P < 0.01) up to the end of storage. The decrease in the biochemical properties of actomyosin was accompanied by a loss in the water holding capacity of the muscles.     

NEW METHOD OF PREDICTING THE BIOCHEMICAL OXYGEN DEMAND OF BREWERY WASTE

The designing of plants for brewery waste water treatment is seriously hampered by the fact that published figures for the biochemical oxygen demand (B.O.D.) of brewery waste are so discordant that no generally applicable averages can be extracted from them. Even in an operating brewery it is a costly and time-consuming affair to procure representative figures by direct measurements, owing to the intricacy of the sampling problems and the inaccuracy of the analytical methods. In an effort to meet this need it is suggested that an objective and sufficiently exact basis for planning treatment plants and for costing treatment is obtainable by estimating the volume and B.O.D. of brewery waste by calculation. It is demonstrated by reference to a practical example how such calculations may be made by keeping account of all materials going into or leaving the brewery.     

ORAL PERCEPTION OF GRITTINESS: EFFECT OF PARTICLE SIZE AND CONCENTRATION OF THE DISPERSED PARTICLES AND THE DISPERSION MEDIUM

The perceptibility of grittiness and the threshold value of grittiness were examined in five disperse model systems: aqueous suspensions, low and high viscous suspensions, and soft and hard gels. Fourteen types of microcrystalline cellulose were used having different particle sizes (between 6–79 μm) and physical properties (shape, degree of polymerization, and state at the material stage). In each system, the proportion of people who perceived grittiness increased with increasing particle size and decreased with increasing particle concentration demonstrating that perception of grittiness depended on both particle size and concentration. The proportion of people who perceived grittiness was found by multiple regression analysis to have a high correlation with the logarithm of (particle size × concentration). Each system gave an approximate regression equation representing this relation. The value of particle size × concentration at the grittiness threshold was defined as the point where 50% of people perceived grittiness. These values were calculated to be 6.0 (aqueous suspension). 19.7 (low viscosity), 26.7 (high viscosity suspension), 30.7 (soft), and 42.1 (hard gel). The factor contributing most to grittiness was concentration, followed by dispersion medium and particle size. The proportion of people who perceived grittiness was also expressed by a multiple regression equation which included these three factors. The obtained results suggest the possibility of predicting and controlling grittiness in foods.