The potential of fruit purees as edible mass transfer barriers was studied. Water vapor and oxygen permeabilities (WVP and O 2 P) of peach puree films were evaluated at different relative humidities (RH) and temperatures (T). Peach puree was not a good water barrier. Peach and apricot films exhibited lower WVPs than pear and apple films. Calcium addition, RH increases and T decreases resulted in increased WVP values for peach puree edible films. WVPs of peach films were compared with other edible and synthetic films. Peach puree films were good oxygen barriers. RH increases resulted in exponential increases in O 2 P. Most edible and many synthetic polymers showed higher O 2 Ps at equivalent conditions.

Piece-size reduction, which is required in preparing lettuce for salads, shortens storage life of cut lettuce as compared to uncut head lettuce. Cellular fluids, released during cutting, are removed by rinsing with water, followed by centrifugation to remove added surface moisture. Extended centrifugation can cause desiccation of product, which may be beneficial under certain conditions. Other methods of water removal, such as blotting or forced air did not seem practical. During storage green pigmentation decreased in salad-cut lettuce. Optimum cold storage was obtained by packaging the cut-lettuce in pouches that had been slightly evacuated and contained a small amount of carbon monoxide.

Osmotic syrups can be reconcentrated and reused for osmotic water removal through at least five complete cycles without adversely affecting the fruit being concentrated, even though the properties of the osmotic medium do change. Syrup penetration rate into a fruit piece was faster with high fructose corn syrup (HFCS) than sucrose. Taste panel evaluation indicated that overall, sucrose was preferred as an osmotic medium over HFCS.

Numerous factors affect the storage stability of shredded Iceberg lettuce, with temperature being most important. Pouches of shredded lettuce stored at 2°C retained a marketable quality 2.5 times longer than those held at 10°C. Also, if the product was sealed in a gas impermeable container it lasted longer. In addition, a sharp blade exercising a slicing action was superior to either a sharp blade chopping or a duU blade slicing or chopping. Smaller shred size reduced storage life, as did the presence of any free moisture or cellular fluids on the lettuce surface. The higher the microbial load the shorter the storage life. Of the chemical dips tested none increased storage life significantly. Physical damaging of the shredded lettuce was detrimental to its storage stability.