On the Volatile Bases and the Volatile Fatty Acids in Pork during the Storage at LOW Temperatures.

In order to determine available methods for assesing the freshness of pork during low temperature storage, the amounts of volatile basic nitrogens (VBNs) and volatile fatty acids (VFAs) of pork in cold storage (chill storage at 7℃) were measured by distillation method and gas chromatogrophy. The pH values, the amounts of total nitrogen (TN), soluble nitrogen (SN), non protein nitrogen (NPN) and changes of external appearance during storage were also examined. Used materials in experiments were two heads of LH strain swine (LH-1, LH-2), but the LH-2 was observed in the watery state (watery pork) from the inspection of slaughter stage. The experimental results were summarized as follows: 1. The amounts of VBNs in chilled park were increased with the storage days, and VBN values of LH-1 of 6-hour after slaughter was 5.18mg.%, but it had increased to 8.54mg.% in 9 days. The deteriolation of LH-2 was more rapid than that of LH-1, because of watery condition. 2. When the chilled pork indicated incipient putrefaction, the ratio of SN/TN was 0.12 and that of NPN/TN was 0.09. 3. VBNs in chilled pork were consited of almost ammonium nitrogen, and trimethylamine was found only small in amounts in the putrid pork. The level of ammonia was increased with the deteriolation. When the quantity of ammonia was more than 0.60 mM in chilled pork, it seemed at the state of incipient putrefaction. 4. Changes in amount of VFA of chilled pork were increased with the storage days. When the chilled pork indicated incipient putrefaction, the VFA values increased to 0.117 meq (LH-1) and to 0.118 meq (LH-2), though those of 6-hour after slaughter were 0.034 meq (LH-1) and 0.056 meq (LH-2). 5. From the chilled pork of LH-1, four VFAs (acetic, formic, n-butyric and propionic) were identified by the gas chromatogram. 6. From the results of this experiment, it seems that measuring of the amounts of acetic acid and ammonia in chilled pork are useful for determining the freshness of chiled pork. (Received Jue 30, 1975)