EFFECTS OF WHEY, WHEY-DERIVED LACTIC-ACID AND SODIUM LACTATE ON THE SURFACE MICROBIAL COUNTS OF RAINBOW-TROUT PACKED IN VACUUM POUCHES

The effects of pasteurized sour cream whey, whey-derived lactic acid a nd sodium lactate on the microbial surface flora of vacuum-packed rain bow trout (Oncorhynchus mykiss) were examined. The commercial culture used in sour cream production consisted of Lactococcus lactis subspeci es cremoris, L. lactis ssp. lactis, L. lactis ssp. diacetilactis and L euconostoc mesenteroides ssp. cremoris After being dipped into test so lutions for 2 min (whey, 20 g/L lactic acid or 20 g/L lactate) the fis h were vacuum-packed and stored at 0 degrees C. The enumeration of the aerobic, anaerobic and psychotrophic bacteria of the skin was perform ed by a plate count after 1, 4, 7 and 10 days' storage. The study was conducted during both spring and autumn. Dipping of fish into whey or lactic acid solution (20 g/L) decreased the microbial growth slightly, whereas 20 g/L sodium lactate solution did not show any anti-microbia l effect. Compared to non treated control fish, mesophilic and psychot rophic counts were significantly lower in lactic acid-treated autumn r ainbow trout samples after 7 and 10 days of storage. (C) 1998 Academic Press.