Biopreservation of paneer using partially purified crude extract (cell-free supernatant) of lactic acid bacteria: Comparative efficacy of Lactobacillus delbrueckii subsp. Bulgaricus and Lactobacillus plantarum during refrigerated storage

Abstract:

The efficacy of partially purified cell-free supernatant (CFS) of two lactic acid bacteria (LAB) as natural biopreservatives for paneer was evaluated during refrigerated storage (4 ± 1 °C). Paneer was surface-treated with CFS at 5.0, 7.5 and 10.0 per cent of Lactobacillus delbrueckii subsp. Bulgaricus (T₁-T₃) and Lactobacillus plantarum (T₄-T₆) and compared with an untreated control (T₀). Samples were analysed every three days for total plate count (TPC), pH, titratable acidity (TA) and sensory quality; coliforms and yeast and mould were absent throughout. In the control and lower doses, TPC rose from about 5.48 to over 6.18 log₁₀ cfu g⁻¹ and sensory scores fell below the limit of acceptability by the ninth day. Only the 10.0 per cent treatments (T₃ and T₆) remained acceptable up to the twelfth day, extending shelf life by about three days, recording significantly lower TPC (5.941 log₁₀ cfu g⁻¹), higher pH (4.85-4.88) and lower TA (≈ 0.58 per cent lactic acid) than the control (6.216 log₁₀ cfu g⁻¹, pH 4.67, 1.157 per cent lactic acid) on day 9. The two organisms behaved comparably, L. Bulgaricus giving marginally lower counts and L. plantarum marginally better late-storage flavour and overall acceptability. Thus, partially purified LAB CFS, particularly at 10.0 per cent, is an effective clean-label biopreservative for paneer.