Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Engineering and Technology Research Center of Food Additives, Beijing Higher Institution Engineering Research Center of Food Additives and Ingredients, Beijing Technology & Business University, Beijing 100048, China.
School of Food and Biological Engineering, Shanxi University of Science & Technology, Xi'an 710021, China.
Molecules. 2019 Apr 26;24(9):1650. doi: 10.3390/molecules24091650.
It is well known that the flavor of skim milk is inferior to whole milk due to the lack of fat. With the popularity of low-fat dairy products, improving the flavor of skim milk is a main focus for food scientists. During the production of skim milk, preheating treatments have a significant effect for the flavor of skim milk. In this study, to explore the optimal processing conditions, milk was preheated at 30 °C, 40 °C, 50 °C, 60 °C for 30 min prior to defatting. When the optimal temperature was determined, milk was then preheated at the optimal temperature for 10 min, 20 min, 30 min, 40 min and 50 min, respectively, to obtain the best preheating time. Distinctions between skim milk samples with different processing conditions were studied by sensory evaluation, e-tongue and HS-SPME-GC-MS analysis. Principle components analysis (PCA) and cluster analysis (CA) were selected to associate with e-tongue results and compare the similarities and differences among the skim milks. Sensory and e-tongue results matched and both showed that a preheating temperature of 50 °C and 30 min time might be the optimal combination of processing conditions. Thirteen volatiles, including ketones, acids, aldehydes, alcohols, alkanes and sulfur compounds, were analyzed to evaluate flavor of the skim milks produced by different preheating treatments. Combined with previous studies, the results indicated that most volatile compounds were decreased by reducing the fat concentration and the typical compound 2-heptanone was not detected in our skim milk samples.
众所周知，由于缺乏脂肪，脱脂牛奶的味道不如全脂牛奶。随着低脂乳制品的普及，改善脱脂牛奶的风味是食品科学家关注的主要焦点。在脱脂牛奶的生产过程中，预热处理对脱脂牛奶的风味有显著影响。在这项研究中，为了探索最佳的加工条件，在脱脂前将牛奶分别在 30°C、40°C、50°C、60°C 下预热 30 分钟。当确定最佳温度时，牛奶在最佳温度下分别预热 10 分钟、20 分钟、30 分钟、40 分钟和 50 分钟，以获得最佳预热时间。通过感官评价、电子舌和 HS-SPME-GC-MS 分析研究了不同加工条件下的脱脂牛奶样品之间的差异。选择主成分分析 (PCA) 和聚类分析 (CA) 将电子舌结果与感官评价结果相关联，并比较脱脂牛奶之间的相似性和差异。感官评价和电子舌结果相匹配，两者都表明预热温度 50°C 和 30 分钟的时间可能是最佳的加工条件组合。分析了包括酮类、酸类、醛类、醇类、烷烃和硫化合物在内的 13 种挥发性化合物，以评估不同预热处理生产的脱脂牛奶的风味。结合以往的研究结果表明，大多数挥发性化合物随着脂肪浓度的降低而减少，并且在我们的脱脂牛奶样品中未检测到典型化合物 2-庚酮。
