食品新鲜度指示卡的研究进展

食品的新鲜度会影响消费者的饮食安全,用指示卡来判断食品的新鲜度具有客观性、科学性,因此,食品新鲜度指示卡的研究和应用具有非常重要的价值。详细阐述了用于标示食品新鲜度的主要化合物、食品新鲜度指示卡的类型及发展趋势。     

浅述肉类新鲜度的检测方法

主要叙述了肉类新鲜度的各种检测方法,从感官检测,理化检测,微生物检测三个方面进行了阐述。     

Model of vegetable freshness perception using luminance cues

Freshness perception is a quality discrimination process that influences our consumer choice and eating behavior, especially of highly perishable products such as vegetables. Previous research used photographic stimuli to investigate the relationship between luminance distribution and freshness perception for a cabbage leaf (C. Arce-Lopera, Masuda, Kimura, et al., 2013) and a strawberry (Carlos Arce-Lopera, Masuda, Kimura, Wada, & Okajima, 2012). In this study, the luminance and chromatic information of the freshness degradation process of four different vegetables (cabbage, strawberry, carrot and spinach) was recorded in a temperature, humidity and light controlled environment. However, instead of a camera, a 2D luminance and chromaticity analyzer (TOPCON UA1000) was chosen as the measurement equipment. Then, using a color management system to guarantee the exact reproduction of the recorded luminance and chromatic data of the real objects, a color and a grayscale version of the stimuli was created. Subsequently, those pictures were randomly presented to subjects who had to rate their perceived freshness using a visual analog scale. The achromatic results did not differ from the chromatic ones suggesting that luminance information is sufficient to enable an accurate estimation of vegetable freshness. Additionally, the original images were digitally manipulated only by modifying their luminance distribution and keeping their color information intact. When the resulting images were presented, using the same psychophysical experimental setting, the results showed that the perceived freshness also changed concordantly with the changes on the asymmetry of the luminance distribution. Finally, a model for vegetable freshness perception that utilizes only luminance cues is presented.     

Web仓储系统中数据时新性标准及其重要意义

Web仓储是使用物化视图方法有效利用Web信息的重要技术。Web仓储系统进行刷新的目标是追求最大的系统时新性,不同的数据时新性标准,决定着不同的系统刷新方案。文章提出了一种基于“状态-效果”的系统时新性标准。分析和实验都表明,所介绍的标准和传统的基于“状态”的标准有着本质不同,它不仅倾向于用户查询结果的最佳化,视图刷新方案也有较强的可操作性,特别适合于复杂多变的Web环境。     

白鲢鱼片在0 ℃贮藏条件下鲜度和品质的变化

以白鲢鱼为研究对象,以菌落总数、挥发性盐基氮（total volatile basic nitrogen,TVB-N）值、pH值、色差值、三甲胺（trimethylamine,TMA）值、2-硫代巴比妥酸（2-thiobarbituric acid,TBA）值为指标,结合电子鼻、质构和感官评价,探究0 ℃条件下鲢鱼片新鲜度变化规律。结果表明,在0 ℃条件下贮藏的鲢鱼片TVB-N值、TMA值、菌落总数值均随贮藏时间的延长而呈增长趋势;pH值先降低后增高;感官评分、硬度和弹性呈降低趋势;电子鼻可以对不同贮藏时间的鲢鱼片进行有效区分;色差值和TBA值对白鲢鱼鱼片品质的判断不具有参考价值。理化指标之间具有相关性,TVB-N值和TMA值与菌落总数值呈显著正相关（RTVB-N值=0.964、RTMA值=0.951）。0 ℃贮藏条件下鲢鱼片的货架期为12 d。     

稻谷新陈度的研究(三)--稻谷在储藏过程中α-淀粉酶活性的变化及其与各储藏品质指标间的关系

对国内不同储藏区域、储藏时间的74个商品稻谷样品的发芽率、脂肪酸值、粘度、还原糖、非还原糖和降落值进行了测定。探索了稻谷在储藏过程中降落数值与储藏时间以及各指标之间的相关性。结果表明：降落数值与储藏时间之间以及降落数值与各储藏品质指标之间均存在一定的相关性。     

温度对水蜜桃保鲜的影响研究

温度是影响水蜜桃保鲜效果的重要因素，低温贮藏常常引起水蜜桃冷害的出现，冷害程度取决于果实的成熟程度和类型。本重点研究了国内外关于温度对水蜜桃保鲜的影响，简单介绍了水蜜桃的采后生理特性、果实性状和常见致病茵，并对水蜜桃保鲜研究的发展趋势进行了讨论。     

基于圆锥形仿生气体室的鸡肉新鲜度电子鼻检测技术

为了快捷、无损检测鸡肉新鲜度,建立了基于圆锥形仿生气体采集室的电子鼻系统。根据鸡肉产生的气味,合理选用了气敏传感器阵列。借鉴嗅觉灵敏的犬类鼻道结构,优化设计了仿生气体采集室。采用RBF神经网络作为模式识别方法。经理化试验结果表明,系统检测鸡肉新鲜度准确率高达98.75%,因此所设计的仿生电子鼻检测鸡肉新鲜度是可行的。     

Application of Electronic Nose for Measuring Total Volatile Basic Nitrogen and Total Viable Counts in Packaged Pork During Refrigerated Storage

The objective of this study was to predict the total viable counts (TVC) and total volatile basic nitrogen (TVB‐N) in pork using an electronic nose (E‐nose), and to assess the freshness of chilled pork during storage using different packaging methods, including pallet packaging (PP), vacuum packaging (VP), and modified atmosphere packaging (MAP, 40% O₂/40% CO₂/20% N₂). Principal component analysis (PCA) was used to analyze the E‐nose signals, and the results showed that the relationships between the freshness of chilled pork and E‐nose signals could be distinguished in the loadings plots, and the freshness of chilled pork could be distributed along 2 first principal components. Multiple linear regression (MLR) was used to correlate TVC and TVB‐N to E‐nose signals. High F and R² values were obtained in the MLR output of TVB‐N (F = 32.1, 21.6, and 24.2 for PP [R² = 0.93], VP [R² = 0.94], and MAP [R² = 0.95], respectively) and TVC (F = 34.2, 46.4, and 7.8 for PP [R² = 0.98], VP [R² = 0.89], and MAP [R² = 0.85], respectively). The results of this study suggest that it is possible to use the E‐nose technology to predict TVB‐N and TVC for assessing the freshness of chilled pork during storage.     

生物保鲜剂处理结合气调包装对冷鲜滩羊肉贮藏品质的影响

目的 研究生物保鲜剂结合气调包装在4±1℃下对冷鲜滩羊肉贮藏品质的影响,探究复合保鲜技术的可行性。方法 以冷鲜滩羊肉的菌落总数为指标,通过响应面优化实验得到二次多项回归模型Y菌落总数和响应面回归方差分析表,并通过验证实验验证复合保鲜剂的合适配比。结果 复合保鲜剂最佳质量配比为：壳聚糖：1.5%、茶多酚：1.2%、Nisin：0.04%;联合保鲜使得样品在0、4、8、12、16、20、24 d在4℃±1℃下的菌数总数、pH、硫代巴比妥酸(thiobarbituric acid reactive substances,TBARS)、挥发性盐基氮(total volatile basic nitrogen,TVB-N)、色泽、蒸煮损失率、硬度、弹性、黏聚性、回复性均随着贮藏时间的延长有不同程度的增加。4±1℃条件下,贮藏后期菌落总数变化速率高于贮藏初期(P<0.05),且实验组的pH、TBARS、TVB-N、蒸煮损失率均高于对照组。贮藏至第16 d时实验组相比对照组菌落总数值相差2.01 lg(CFU/g)、pH相差0.69、TBARS相差0.56 mg/kg、TVB-N相差0.92 mg/100 g、蒸煮损失率相差1.7%,同时实验组肉贮藏期间a*优于对照组,肉的硬度、弹性、回复性均下降缓慢。结论 生物保鲜剂联合气调包装(75% O2+20% CO2+5% N2)可以维持冷鲜滩羊肉贮藏期间的良好品质且根据冷鲜肉微生物标准可以延长货架期约4~6 d。