The composition and some qualitative aspects of ground beef offered for sale in Corvallis, Oregon were studied. Samples were purchased from six retail markets twice weekly throughout a six week test period. Three stores were independently owned and operated and three were chain stores. Differences in moisture, fat and protein levels of ground beef samples among the six stores and between chain and independently owned stores were statistically significant. Differences in composition between sampling days (Tuesday versus Friday) and between replicate weeks were generally not significant. Ground beef from chain stores was generally characterized by higher moisture and protein levels and lower fat levels. Thirty-two percent of all samples (50 percent of the independent stores and 14 percent of the chain stores) exceeded the legal limit of 30 percent fat. Moisture:protein ratios ranged from 2.53 to 4.24 while the average value was 3.59. About 28 percent of all samples had ratios in excess of 3.70. Differences in moisture:protein ratios between chain and independent stores were not significant. Although differences in extract-release volume (ERV) of ground beef obtained from the various stores were significant, differences between sampling days, replicate weeks and chain versus independent stores were not. Resazurin reduction times of ground beef among individual stores, between sampling days, replicate weeks and chain versus independent stores were not significantly different. The correlation between ERV and resazurin reduction time was low (r = 0.21) suggesting a poor relationship between these two procedures for assessing microbial contamination in ground beef. Differences in nonprotein nitrogen (NPN) levels of samples among stores and between sampling days were statistically significant. Only minor differences in NPN levels between store types and replicate weeks were observed. Soluble protein levels appeared to be a reflection of total protein. Iodine numbers of ground beef fat ranged from 43.7 to 53.6 and were significantly higher in ground beef purchased from chain stores. Price per pound of ground beef and price per pound of protein were significantly different among the six stores. The price per pound of meat was significantly higher in the chain stores than in the independent stores. However, price per pound of protein and price per pound of soluble protein were essentially the same for the two types of stores. Recommendations for quality control of ground beef sold at the retail level are discussed. / Graduation date: 1968

Graduation date: 1970