Authors
Title
Abstract
The objective of the research study was to assess the oxidative changes in dry-fermented meat products with the addition of probiotic bacteria of Lactobacillus and Bifidobacterium genere during four-month refrigeration storage. Four experimental variants of the products were prepared: control sample without any probiotic strain added (K) and three samples with the addition of probiotic strains of Lactobacillus acidophilus Bauer (W1), Bifidobacterium bifidum (W2), Lactobacillus acidophilus Bauer, and Bifidobacterium bifidum in a 1: 1 mixture (W3). The meat was cured during a period of 72 hrs with use of a dry method and with a 3% curing mixture (sodium chloride, sodium nitrite, sodium nitrate) added. Next, 0.05% sodium ascorbate, 1.2% glucose, and probiotic bacteria, amounting to 2 × 106 cfu/g of meat, were added. After ripening at a temperature of 16˚C for 21 days, the products were vacuum-packed and stored at a temperature of 4 ˚C for 4 months. In the samples, the following parameters of adipose and muscle tissues were determined: active acidity (pH value), acid value, peroxide value, p-anisidine value, TBARS index, and colour parameters in the CIE L*a*b* system. It was found that in all the samples the acidity was on a similar level during the storage period. The lowest pH values were found in the W3 sample (after ripening– 5.41; after two months of storage – 5.20; after four months – 5.80). A statistically significant (p < 0.05) increase was found in the acid value of all the samples during their storage. Almost a threefold increase in the content of free fatty acids (39.31 mg KOH/g of fat) was reported in the K control sample after 4-month storage compared to the value after 2 month storage (12.95 mg KOH/g of fat). The increase in all other samples was lower. The W2 sample was characterized by the lowest peroxide value (0.25 mEq/kg of fat) after 2-month storage; this value increased to 0.80 mEq/kg of fat after four months of cold storage. The TBARS value remained at a low level in all the samples during the first two months of storage. After that, it significantly (p<0.05) increased to 2.35 mg MDA/kg of product in the control sample after four month storage; however, in the W1, W2, and W3 samples with probiotic bacteria, it increased to 1.81, 0.97, and 1.16 mg MDA/kg of product, respectively. A spectrophotometric assessment of the colour parameters of the product did not show significant differences (p < 0.05) among the L*, a*, b* parameters of all the samples during the refrigeration storage period. It was proved that the probiotic bacteria, added to dry-fermented pork necks during the production process, affected the inhibition of oxidative changes in those products during ripening and four-month storage.
Keywords
dry-fermented pork necks, probiotics, fat oxidation, storage