Monitoring the microbial populations and temperatures of fresh broccoli from harvest to retail display.

Microbial populations and the temperature of fresh broccoli were monitored at several steps of a supply chain by sampling 33 distinct lots of locally grown produce over two seasons during harvest, storage, wholesale handling, and retail display. Imported broccoli was also sampled, but only at retail display. Microbiological analyses were conducted on the florets of 201 local and 60 imported broccoli samples to determine populations of total aerobic bacteria (aerobic colony count), fecal coliforms, Escherichia coli, and Listeria monocytogenes. All the samples had mean aerobic colony counts ranging between 4 and 6 log CFU/g, but L. monocytogenes was not detected (limit of detection =100 CFU/g). Fecal coliforms and E. coli (limit of detection =20 most probable number per 100 g) were found in 22 of 126 samples of local broccoli collected at various steps of the production and distribution system during the first season. None was found in 75 samples collected in the second season. Fecal coliforms and E. coli were found in 2 of 60 imported broccoli samples. Broccoli temperatures were relatively well controlled throughout the production and distribution system. No clear change in produce microbial populations was evident between harvest and retail display, during both sampling seasons. However, a large experimental variability was found, possibly associated with the high variability of the initial levels of microbial populations on broccoli at harvest.

Temperatures and ages of packs of beef displayed at stores in Canada.

The surface temperatures and ages of 1703 retail packs of chilled, raw beef in cut or ground forms on display in a case at each of 41 Canadian retail stores were determined. For each case, data were collected from packs at pre-selected positions in the case. Data for a position were not collected if a pack of beef was not present there. Data were collected at a different time on each of 3 days, with each store being visited within l h after opening and l h before closing and between 12:00 and 14:00 h, without regard to the operation of the case defrosting cycle. The median temperatures of pack surfaces were <4 °C, between 4 and 7 °C, and >7 °C at 24, 16 and one stores, respectively. The maximum temperatures were <4 °C, between 4 and 7 °C and >7 °C at 3, 18, and 20 stores, respectively. The median ages were 0 day, 1 day, and 2 or 3 days at 19, 17 and 5 stores, respectively. The maximum ages were ⩽2 days, between 2 and 4 days, and >4 days at 21, 14 and six stores, respectively. Temperatures were generally lower at the backs than at the fronts of cases, on upper than on bottom shelves, and within than on the tops of stacks of packs. Temperatures were apparently not affected by the positions of packs along the lengths of cases, and did not differ at different times of day.

Temperatures and ages of boxed beef packed and distributed in Canada.

Boxes of beef were examined when product was packed and when boxes were loaded out of five packing plants, when boxes were loaded into and loaded out of seven refrigerated warehouses, and when boxes were received and opened at 21 retail stores. At each stage of handling at each facility, the boxes to be examined were selected at random. For each selected box, the temperature of product at the centre of the box was measured, and the date of packing and the plant of origin were noted. When cuts were packed, the minimum, median and maximum temperatures were about 2, 6 and 18 °C, respectively. Temperatures were successively lower when boxes were loaded out of packing plants, into warehouses and out of warehouses. When loaded out of warehouses, the minimum, median and maximum temperatures were about -2, 1 and 8 °C, respectively. The ranges of temperatures were similar, but the median temperatures were about 2 or 1.5 °C, respectively, when boxes were received at or were opened at retail stores. At packing plants and warehouses, the temperatures of manufacturing and ground beef were lower than those of cuts, but at the retail store the temperatures of all types of product were similar. When boxes were opened at retail stores, the minimum, median and maximum ages of cuts were about 2, 20 and 130 days, respectively; and the corresponding ages for manufacturing and ground beef were 2, 7 and 56 days, respectively. The data indicate that boxed beef is generally cooled to and maintained at temperatures within the range sought by the meat industry. However, cooling to chiller temperatures of product that is packed while warm can take several days; and some product is held for times that are excessive in view of the temperatures of boxed beef.