Specialty salad greens: Postharvest physiology and shelf-life

A mixture of fresh young specialty leafy greens, known as the "California Salad", is an increasingly popular salad item. We evaluated the physiological behaviour and shelf-life of 17 different commercially grown cool-season specialty greens. These included green and red-leaf lettuces (Lactuca sativa), spinach (Spinacia oleracea) and chards (Beta vulgaris), and several members of the Brassicaceae (e.g., arugula, tat-soi, mizuna, red mustard, and kale). Average respiration rates (2 to 5 days after harvest) of lettuces and chards were similar, averaging 4.5+/-0.7 and 21.3+/-3.5 mu l CO2/g-h at 0 degrees and 10 degrees C, respectively. Respiration rates of the specialty crucifers averaged 60% higher. Ethylene production rates for the range of young specialty greens averaged 0.4 and 1.2 nl/g-h at 0 degrees C and 10 degrees, respectively. Decay and loss of green color were the most common postharvest defects, wheras in commercial handling, weight loss is another contributor to postharvest losses. Shelf-life of all the greens was best maintained at 0 degrees C. An average 90% of product volume was still marketable after 21 days at 0 degrees C. Less than 70% of the product was marketable after 7 days at 10 degrees C. At 5 degrees C, 89% and 69% of the product volume was marketable after 7 and 14 days, respectively.