14A-32 |
Non starter lactic acid bacteria and calcium lactate crystal formation in Cheddar cheese |
S. AGARWAL1, S. Clark1, B. G. Swanson1, and G. Ü. Yüksel2. (1) Dept. of Food Science & Human Nutrition, Washington State Univ., 106 FSHN Bldg., PO Box 646376, Pullman, WA 99164-6376, (2) Dept. of Food Science & Toxicology, Univ. of Idaho, 205 Agricultural Biotechnology Lab., PO Box 442201, Moscow, ID 83844-2201 Calcium lactate crystals (CLC) continue to be a problem and expense for Cheddar cheese manufacturers. This research was designed to investigate the source of non-starter lactic acid bacteria (NSLAB), and study the role of NSLAB in CLC formation. A sanitized cheese manufacturing facility was swabbed for the presence of NSLAB and the microbial population of raw materials and finished product were analyzed to locate the sources of contamination. Changes in microbial population during production on the equipment surface and in cheese were analyzed. Changes in microbial counts in cheese samples were studied during ripening. In pilot plant experiments, filled vats were inoculated with Lactococcus lactis starter culture (108cfu/ml) and with or without cheese plant isolates, Lactobacillus curvatus or Pediococci acidilactici, as adjunct cultures (102cfu/ml). Cheeses were aged at 7.2oC or 10oC for 6 months. Locations with greatest residual NSLAB contamination (102-4cfu/ml) included raw milk silo, ultafiltration unit, Cheddaring belt and cheese tower. The population of L. curvatus in cheese reached 107 in just 14 days while P. acidilactici reached 106 in 30 days. Higher NSLAB counts were observed in the first month in cheese aged at 10oC compared to cheese aged at 7.2oC. Total lactic acid bacteria count decreased faster in cheeses aged at 10oC compared to cheeses aged at 7.2oC after 1 month. In cheeses without adjunct culture or with P. acidilactici, crystals were not observed on cheese surfaces within 6 months, but crystals were observed at the end of 2 months in cheeses containing L. curvatus. The research shows that even low levels of contamination with certain NSLAB can cause formation of CLC. Additionally, high aging temperatures increase the occurrence CLC in maturing Cheddar cheese.
Session 14A, Dairy Foods: General developments in dairy technology I
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