Packaging Lab, Instituto de Agroquímica y Tecnología de Alimentos, IATA-CSIC, Av. Agustín Escardino 7, 46980 Paterna, Spain.
Packaging Lab, Instituto de Agroquímica y Tecnología de Alimentos, IATA-CSIC, Av. Agustín Escardino 7, 46980 Paterna, Spain.
Int J Food Microbiol. 2021 Feb 2;339:109007. doi: 10.1016/j.ijfoodmicro.2020.109007. Epub 2020 Dec 2.
Cast films obtained from polyvinyl alcohol (PVOH) blended with casein hydrolysates (HCas) in a weight ratio of 1:1 were employed to carry nisin-producing L. lactis and phytic acid in order to broaden the antimicrobial spectrum of L. lactis to Gram-positive and Gram-negative spoilage and pathogen bacteria. For this purpose, the effect of the antimicrobial activity of various film formulations and combinations of films on the growth of E. coli at 37 °C for 24 h was studied. The film system that showed antimicrobial activity against Gram-negative bacteria consisted of phytic acid and L. lactis incorporated in separate films. When the active agents were in the same film the viability of L. lactis decreased considerably and it did not exert antimicrobial activity against the bacterium. Therefore, the combination of L. lactis and phytic acid in separate films was chosen as the reliable system, and the effect of its activity on the growth of Gram-negative bacteria (E. coli, Salmonella enterica, and Pseudomonas fluorescens) and Gram-positive bacteria (Listeria monocytogenes) in liquid culture medium was tested at refrigeration temperature (4 °C), and with simulated breaks in the cold chain (14 °C and 24 °C). The survival of L. lactis in coexistence with these bacteria was also studied. The film system exerted an antimicrobial effect against the Gram-negative bacteria tested, and the activity depended on the bacteria and the temperature assayed. With regard to the antimicrobial activity against L. monocytogenes, phytic acid improved the antimicrobial capacity of L.lactis. The survival of L. lactis was maintained at 7-8 log (CFU/mL) culture in liquid medium throughout the storage period. The films developed were intended to be used as coatings in the design of a double-sided active bag for a non-fermented dairy product. The bags were filled with homemade preservative-free pastry cream, and the microbiological shelf life and evolution of pH of the packaged ready-to-eat food stored at 4 °C was studied for 20 days. The results showed a reduction in the growth of spoilage bacteria and therefore an increase in the shelf life of the packaged product. The films developed could be applied in the design of packages for perishable dairy foods in order to increase their microbiological shelf life.
采用聚乙烯醇（PVA）与水解酪蛋白（HCas）以 1:1 的重量比混合制成的铸膜液来负载产粘菌素乳杆菌和植酸，以拓宽乳杆菌的抗菌谱，使其能够抑制革兰氏阳性和革兰氏阴性腐败和病原菌。为此，研究了不同膜配方和膜组合对 37°C 下大肠杆菌生长 24 小时的抗菌活性的影响。含有植酸和分别包埋的乳杆菌的膜系统显示出对革兰氏阴性菌的抗菌活性。当活性物质在同一片膜中时，乳杆菌的存活率会大大降低，并且对细菌没有抗菌活性。因此，选择将乳杆菌和植酸分别包埋在两片膜中的组合作为可靠的系统，并测试其在冷藏温度（4°C）和模拟冷链中断（14°C 和 24°C）条件下对液体培养基中革兰氏阴性菌（大肠杆菌、肠炎沙门氏菌和荧光假单胞菌）和革兰氏阳性菌（单核细胞增生李斯特菌）的生长的活性。还研究了这些细菌共存时乳杆菌的存活情况。该膜系统对所测试的革兰氏阴性菌表现出抗菌作用，其活性取决于细菌和测试温度。关于对抗单核细胞增生李斯特菌的抗菌活性，植酸提高了乳杆菌的抗菌能力。在整个储存期内，液体培养基中乳杆菌的存活保持在 7-8 个对数（CFU/mL）培养物。所开发的薄膜旨在用作非发酵乳制品双面活性袋设计的涂层。袋子中装满了自制的无防腐剂糕点奶油，并研究了在 4°C 下储存的包装即食食品的微生物保质期和 pH 值变化，为期 20 天。结果表明，腐败菌的生长减少，因此包装产品的保质期延长。所开发的薄膜可应用于易腐乳制品包装的设计，以延长其微生物保质期。
