Improvement of microbiological safety and shelf-life of pulse spreads through sous vide and high pressure processing
Latvia University of Agriculture, Faculty of Food Technology, Department of Food Technology, 22 Rigas Street, LV3004, Jelgava, Latvia
Microbiological quality of sous vide treated (80 °C/15 min) and high pressure processed (700 MPa/10 min/20 C) cowpea (Vigna unguiculata (L.) Walp. cv. Fradel) and maple pea (Pisum sativum var. arvense L. cv. Bruno) spreads in flexible vacuum packaging during 62-day storage at 5 ± 1 °C were assessed. Pulse spreads, made from cooked pulses with salt, citric acid, oil, and seasoning, were filled in PA/PE or PET/ALU/PA/PP flexible film pouches, packaged in vacuum (20 mbar) and hermetically sealed. Microbiological testing was performed by determining total plate count, yeast and mould count on days 0, 15, 29, 42, 50, 57, and 62, and the presence of B. cereus, C. perfringens and E. coli before processing and after 62-day storage. The results showed that total plate count increased significantly after 62-day storage in both sous vide (P = 0.011) and high pressure processed (P = 0.017) spreads; the observed over one-log increase was without significant differences between pulse spreads and packaging materials (P < 0.05). The admissible level of total plate count (Nmax < 3.69 log CFU g-1) in pulse spreads was not exceeded. The presence of yeasts and moulds, C. perfringens and E. coli in pulse spreads was not confirmed, whereas B. cereus accounted to <102 CFU g-1 after 62-day storage. The suggested shelf-life of processed pulse spreads is 62 days; except for sous vide treated spreads with seasoning in both packaging materials- 57 days. Both processing methods are suitable to ensure the production of high quality pulse spreads with adequately long shelf-life.