Search

The effects of packaging treatments, postharvest cooling delay and storage duration on color, texture, ascorbic acid content, weight loss and glucosinolate retention in crown-cut heads of broccoli were studied. Broccoli stored in shrink wrap film lost 3.7% of its original weight, whereas ice packaging resulted in 17.4% weight loss during storage. Long postharvest cooling delay and storage duration negatively affected broccoli color. Broccoli heads stored in shrink wrap packaging retained firmness longer than broccoli stored in ice. Ascorbic acid retention was improved in shrink wrapped broccoli, but retention decreased as postharvest cooling delay and storage duration lengthened. Shrink wrapped broccoli exhibited improved retention of the glucosinolate, glucoraphanin. During storage, “Gypsy” broccoli maintained better quality than “Everest” with respect to color, ascorbic acid retention and weight loss. However, “Everest” retained texture (firmness) better after 35 days of storage. Shrink wrap packaging and shorter postharvest cooling delays preserve broccoli quality and increase shelf life. PRACTICAL APPLICATIONS Broccoli has the potential to be a high value crop if the shrink wrap packaging technology can be disseminated to the broccoli growers. Typically, farmers use ice for cooling broccoli heads after harvest, which is an expensive and difficult practice. Without icing requirement, broccoli marketing will be easy and opens up significant potential for broccoli producers who can afford relatively inexpensive film wrapping machines (as compared with ice equipment) in conjunction with onsite cooling. Sometimes onsite cooling is not possible and delays may be involved before the harvested produce is cooled. The conclusions reached in this study shows that shrink wrap packaging can be used to improve quality, retain phytochemical content and prolong the shelf life of crown-cut broccoli.

Type of thermal process [high temperature, short time pasteurization (HTST) or ultra-high temperature pasteurization (UHT)] and homogenization sequence (before or after pasteurization) were examined for influence on the physicochemical properties of natural cream (20% milk fat) and creams formulated with 20% low-melt, fractionated butteroil emulsified with skim milk, or buttermilk and butter-derived aqueous phase. Homogenization sequence influenced physicochemical makeup of the creams. Creams homogenized before pasteurization contained more milk fat surface material, higher phospholipid levels, and less protein at the milk fat interface than creams homogenized after pasteurization. Phosphodiesterase I activity was higher (relative to protein on lipid globule surface) when cream was homogenized before pasteurization. Creams formulated with skim milk and modified milk fat had relatively more phospholipid adsorbed at the milk fat interface. Ultra-high-temperature-pasteurized natural and reformulated creams were higher in viscosity at all shear rates investigated compared with HTST-pasteurized creams. High-temperature, short time-pasteurized natural cream was more viscous than HTST-pasteurized reformulated creams at most shear rates investigated. High-temperature, short time-pasteurized creams had better emulsion stability than UHT-pasteurized creams. Cream formulated with buttermilk had creaming stability most comparable to natural cream, and cream formulated with skim milk and modified butteroil was least stable to creaming. Most creams feathered in a pH range of 5.00 to 5.20, indicating that they were moderately stable to slightly unstable emulsions. All processing sequences yielded creams within sensory specifications with the exception of treatments homogenized before UHT pasteurization and skim milk formulations homogenized after UHT pasteurization.

Emulsifying properties of milk-derived components influence the physical characteristics of reformulated creams. Fractionated butter oils with different melting ranges (low-melt: 10 to 25 degrees C; medium-melt: 25 to 35 degrees C) were recombined into fluid dairy systems using skim milk, or sweet buttermilk and butter-derived aqueous phase to manufacture 20% milk fat creams. Separation temperature (49 degrees C or 55 degrees C) in obtaining emulsifying components was examined for its effect on physical properties of pasteurized reformulated creams. Rate of creaming, viscosity, feathering, and sensory characteristics of reformulated and natural creams stored at 3.3 degrees C were evaluated over a 13-d period. Creaming rate of reformulated and natural creams was unaffected by formulation and was most influenced by duration of storage. Melting characteristics of butter oils influenced viscosity at some shear rates. With the exception of natural cream, all formulations were consistent in apparent viscosity during the 2-wk storage period. All creams feathered in a pH range of 4.70 to 5.20 and were classified as moderately stable to slightly unstable. All reformulated and natural creams met sensory quality specifications with the exception of creams formulated with skim milk and lower melting range butteroil. Creams formulated with buttermilk, butter-derived aqueous phase, and lower-melting range butter oil most closely mimicked natural creams with regard to sensory quality and viscosity.