Faculty of BioScience and Technology for Food, Agriculture and Environment, University of Teramo, Via Renato Balzarini 1, 64100 Teramo, Italy.
Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Via Campo Boario 37, 64100 Teramo, Italy.
Molecules. 2020 May 10;25(9):2249. doi: 10.3390/molecules25092249.
The aim of the study was to evaluate the proteolytic process in Caciocavallo cheese obtained from Friesian cows fed zinc, selenium, and iodine supplementation. Thirty-six Friesian cows, balanced for parity, milk production, and days in milk, were randomly assigned to four groups. The control group (CG) was fed with a conventional feeding strategy, while the three remaining groups received a diet enriched with three different trace elements, respectively zinc (ZG), selenium (SG), and iodine (IG). At the end of the experimental period, samples of milk were collected and used to produce Caciocavallo cheese from each experimental group. Cheese samples were then analyzed after 7 and 120 days from the cheese making in order to obtain information on chemical composition and extent of the proteolytic process, evaluated through the electrophoretic analysis of caseins and the determination of volatiles profile. Both milk and cheese samples were richer in the amount of the microelement respectively used for the integration of the cattle's diet. The zymographic approach was helpful in evaluating, in milk, the proteolytic function performed by endogenous metalloenzymes specifically able to degrade gelatin and casein; this evaluation did not highlight significant differences among the analyzed samples. In cheese, the electrophoretic analysis in reducing and denaturing condition showed the marked ability of β-casein to resist the proteolytic action during ripening, whereas the dietary selenium supplementation was shown to perform a protective action against the degradation of S1 and S2 isoforms of α-casein. The analysis of the volatile profile evidenced the presence of compounds associated with proteolysis of phenylalanine and leucine. This approach showed that selenium was able to negatively influence the biochemical processes that lead to the formation of 3-methyl butanol, although the identification of the specific mechanism needs further investigation.
本研究旨在评估经锌、硒和碘补充喂养的弗里斯奶牛所产卡苏奥洛干酪的蛋白水解过程。36 头弗里斯奶牛按胎次、产奶量和泌乳天数均衡分组，随机分为四组。对照组（CG）采用常规饲养策略，而其余三组则分别添加了三种不同微量元素的饲料，即锌（ZG）、硒（SG）和碘（IG）。在实验期末，收集牛奶样本并用于从每个实验组生产卡苏奥洛干酪。然后在奶酪制作后 7 天和 120 天分析奶酪样本，以获得有关化学组成和蛋白水解过程程度的信息，通过对酪蛋白的电泳分析和挥发性物质图谱的测定进行评估。牛奶和奶酪样本中分别含有更多用于牛饲料添加的微量元素。在牛奶中，胶凝和酪蛋白的内源性金属酶的蛋白水解功能通过胶凝和酪蛋白的电泳分析进行了评估，该评估没有显示出分析样本之间的显著差异。在奶酪中，在还原和变性条件下的电泳分析显示了 β-酪蛋白在成熟过程中抵抗蛋白水解作用的明显能力，而膳食硒补充则表现出对 S1 和 S2 同工型 α-酪蛋白降解的保护作用。挥发性物质图谱的分析证实了与苯丙氨酸和亮氨酸蛋白水解相关的化合物的存在。该方法表明，硒能够对导致 3-甲基丁醇形成的生化过程产生负面影响，尽管需要进一步研究来确定具体的机制。
