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Title: RAPID METHODS TO ASSESS SPOILAGE OF BEEF

Author
item VENKITANARAYANAN - UNIV OF CONN
item FAUSTMAN CAMERON - UNIV OF CONN
item Berry, Bradford

Submitted to: Food Preservation 2000 Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/14/1994
Publication Date: N/A
Citation: N/A

Interpretive Summary: Frequently, spoilage bacteria can reach very high levels on meat products before being detected by sight or smell. Determination of bacteria by traditional methods, while precise, takes too long to assist in making judgements regarding present or future use of meat products. This study involved the comparison of four potential rapid indices of meat spoilage on both irradiated and non-irradiated beef. With irradiated beef (no bacteria present) it was determined that acid phosphatase enzyme activity was present in the meat itself to prevent this from being a suitable indicator of spoilage. However, fluorescein diacetate hydrolysis (three hours to complete) and resazurin reduction time (< 1 hr to show a color change with spoiled beef) were shown to be rapid indicators of spoilage bacteria numbers.

Technical Abstract: The growth of spoilage bacteria results in abbreviated shelf-life of muscle foods. Current methods for determining bacterial load require 48 hrs for results; thus there is a need for rapid methods to predict the bacterial population and shelf-life of meat. Preliminary experiments suggested that acid phosphatase (AP), fluorescein diacetate hydrolysis (FDA), resazurin reduction time (RR) and color ("a" value) of meat could be used as indices of meat spoilage. However, it was unclear whether these measures were inherently present in meat, or contributed by the associated bacterial flora. Thus, AP activity, FDA, RR and "a" value were monitored in irradiated and non-irradiated beef. For non- irradiated beef, RR steadily decreased as aerobic plate count (APC) increased; an RR value of 4.20 hr was required when APC reached a log value of 7.5. With irradiated beef, the RR did not change with storage. Both irradiated and non-irradiated samples demonstrated FDA activity, however, the activity in non-irradiated beef increased during storage. While irradiated samples were devoid of any bacteria, a slightly higher AP activity than that in non-irradiated beef was observed suggesting that meat contains inherent AP. No difference in "a" values was observed between irradiated and non-irradiated samples. This study indicated that RR and FDA could be used effectively to indicate spoilage of meat