248 Produce Degradation: Reaction Pathways and their Prevention
8.9.4 WAXING
Waxing of certain fruits and vegetables reduces their rate of respiration and enhances
product gloss, improving merchandising and marketing (Salunkhe et al., 1991). For
example, waxing of cassava tubers extends the market life of the roots for up to
1 month by reducing the rate of gas transfer between the tissues and the atmosphere
(Salunkhe et al., 1991; Kadam and Salunkhe, 1998). Waxing is applied by foaming,
dipping, or brushing. Waxing emulsions may contain some fungicide to protect the
produce from fungal attack. They also reduce losses due to transpiration and respi-
ration. In some fruits, for example citrus, dyes are added to the waxes to enhance
the merchandising quality and prolong shelf life by partially covering lenticels and
stomata, thus reducing water and water-soluble nutrient losses due to transpiration
and respiration (Salunkhe et al., 1991).
8.9.5 COATING WITH EDIBLE FILMS
Preservation of fruits and vegetables by using edible films is becoming more popular
nowadays, although information on the nutrient retention of preserved fruits and
vegetables preserved by edible films is not widely available. Edible films can act as
barriers to prevent losses of flavor, texture, and nutrients (McCarthy and Matthews,
1994). For example, a casein-based film with a small amount of ascorbic acid added
for increased protection against browning kept a sample of small pieces of sliced
and peeled apples fresh for six d, while unfilmed apple pieces shriveled and turned
brown within 2 h. Likewise, avocados treated by edible films remained fresh for 6 d
without blackening (McCarthy and Matthews, 1994). Another edible film made of
vegetable oil, cellulose, and an emulsifier is used in fruits and vegetables as an
antioxidant atmospheric barrier. In a laboratory experiment with mature green toma-
toes, only 40% of the tomatoes treated with the film ripened after 14 d of storage,
compared with 100% ripening for the untreated tomatoes. Similar experiments with
oranges and carambolas showed excellent results. This emulsified edible film has
proved to be an invaluable aid to the fresh and minimally processed fruits and
vegetable industry in preventing spoilage and retaining nutrients (Sanchez, 1990).
With the increasing trend toward buying foods that are ready to use and easily stored,
edible films have a potential benefit to consumers, restaurants, and others in the food
industry who want to purchase fresh and minimally processed fruits and vegetables
(USDA, 1989).
8.10 NUTRITIONAL IMPLICATIONS
OF PRODUCE PROCESSINGThe aim of produce processing is to improve the storage life and extend the avail-
ability of perishable foods over a longer period of time. The food processing tech-
niques used, however, may limit the availability of some essential nutrients. Maxi-
mizing nutrient retention during thermal processing of produce has been a
considerable challenge for the food industry. The losses of nutrients as a result of
processing have been divided into three categories: intentional, accidental, and