Effects of high-pressure treatment on shelf life and quality of fresh lactic curd cheese

Abstract

High-pressure processing (HPP) was investigated for controlling spoilage and extending the shelf life of fresh lactic curd cheese. Fresh lactic curd cheeses manufactured from pasteurised bovine milk using Lactococcus starters and flavourings were vacuum packed and subjected to pressures at the levels of 300 and 600 MPa for 5 min, up to a temperature of 22°C, then stored at 4°C. The number of spoilage yeasts and moulds were enumerated immediately after treatment and at time intervals of three, five and eight weeks of storage. The growth of yeasts and moulds was effectively controlled for up to eight weeks in samples pressurised at 300 and 600 MPa. The firmness and adhesiveness of the samples, analysed with a TA-XT2 Texture Analyser, gradually increased during storage, but no significant differences (p>0.01) in textural properties were detected between pressure-treated and untreated samples. An untrained taste panel (n=12) also found no significant differences (p>0.01) in the sensory characteristics of the pressure-treated and untreated samples in a ranking test. Cheeses pressurised at 600 MPa developed TCA-soluble peptides at a significantly lower rate (p<0.01) than the untreated controls during storage up to eight weeks. High-pressure treatment was an effective process to control yeasts and moulds spoilage and extend the shelf-life of fresh lactic curd cheese without adverse effects on the sensory and textural attributes of the products