Mileriene Justina, Serniene Loreta, Henriques Marta, Gomes David, Pereira Carlos, Kondrotiene Kristina, Kasetiene Neringa, Lauciene Lina, Sekmokiene Dalia, Malakauskas Mindaugas
Department of Food Safety and Quality, Veterinary Academy, Lithuanian University of Health Sciences, Tilžės str. 18, LT-47181 Kaunas, Lithuania.
Department of Food Safety and Quality, Veterinary Academy, Lithuanian University of Health Sciences, Tilžės str. 18, LT-47181 Kaunas, Lithuania.
J Dairy Sci. 2021 Feb;104(2):1504-1517. doi: 10.3168/jds.2020-18732. Epub 2020 Dec 11.
Fresh unripened curd cheese has long been a well-known Eastern European artisanal dairy product; however, due to possible cross-contamination from manual production steps, high moisture content (50-60%), and metabolic activity of present lactic acid bacteria, the shelf life of curd cheese is short (10-20 d). Therefore, the aim of this study was to improve the shelf life of Eastern European acid-curd cheese by applying an antimicrobial protein-based (5%, wt/wt) edible coating. The bioactive edible coating was produced from liquid whey protein concentrate (a cheese production byproduct) and fortified with 0.3% (wt/wt, solution basis) Chinese cinnamon bark (Cinnamomum cassia) CO extract. The effect of coating on the cheese was evaluated within package-free (group 1) and additionally vacuum packaged (group 2) conditions to represent types of cheeses sold by small and big scale manufacturers. The cheese samples were examined over 31 d of storage for changes of microbiological (total bacterial count, lactic acid bacteria, yeasts and molds, coliforms, enterobacteria, Staphylococcus spp.), physicochemical (pH, lactic acid, protein, fat, moisture, color change, rheological, and sensory properties). The controlled experiment revealed that in group 1, applied coating affected appearance and color by preserving moisture and decreasing growth of yeasts and molds during prolonged package-free cheese storage. In group 2, coating did not affect moisture, color, or texture, but had a strong antimicrobial effect, decreasing the counts of yeasts and molds by 0.79 to 1.55 log cfu/g during 31 d of storage. In both groups, coating had no effect on pH, lactic acid, protein, and fat contents. Evaluated sensory properties (appearance, odor, taste, texture, and overall acceptability) of all samples were similar, indicating no effect of the coating on the flavor of curd cheese. The edible coating based on liquid whey protein concentrate with the incorporation of cinnamon extract was demonstrated to efficiently extend the shelf life of perishable fresh curd cheese, enhance its functional value, and contribute to a more sustainable production process.
新鲜的未成熟凝乳奶酪一直是东欧著名的手工乳制品；然而，由于手工生产步骤可能导致交叉污染、高水分含量（50-60%）以及现存乳酸菌的代谢活性，凝乳奶酪的保质期较短（10-20天）。因此，本研究的目的是通过应用基于抗菌蛋白（5%，重量/重量）的可食用涂层来延长东欧酸凝乳奶酪的保质期。这种生物活性可食用涂层由液体乳清蛋白浓缩物（一种奶酪生产副产品）制成，并用0.3%（重量/重量，基于溶液）的中国肉桂（桂皮）CO提取物进行强化。在无包装（第1组）和另外真空包装（第2组）的条件下评估涂层对奶酪的影响，以代表小规模和大规模制造商销售的奶酪类型。在储存31天的过程中，对奶酪样品进行微生物（总细菌数、乳酸菌、酵母和霉菌、大肠菌群、肠杆菌、葡萄球菌属）、理化（pH值、乳酸、蛋白质、脂肪、水分、颜色变化、流变学和感官特性）变化的检测。对照实验表明，在第1组中，应用的涂层通过在无包装的奶酪长时间储存期间保持水分并减少酵母和霉菌的生长，从而影响外观和颜色。在第2组中，涂层对水分、颜色或质地没有影响，但具有很强的抗菌作用，在储存31天期间，酵母和霉菌的数量减少了0.79至1.55 log cfu/g。在两组中，涂层对pH值、乳酸、蛋白质和脂肪含量均无影响。所有样品的感官特性（外观、气味、味道、质地和总体可接受性）评估结果相似，表明涂层对凝乳奶酪的风味没有影响。基于液体乳清蛋白浓缩物并加入肉桂提取物的可食用涂层被证明能有效延长易腐新鲜凝乳奶酪的保质期，提高其功能价值，并有助于实现更可持续的生产过程。
