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582 Part 5: Fruits, Vegetables, and Cereals2003). The quality of MPR F & V can be increased by following
Good Manufacturing Practices, the main points of which are:
minimizing handling frequency, providing continued control of
temperature, the relative humidity (% RH), modified atmosphere
and controlled atmosphere (MA/CA storage etc.). The product
is always transferred from truck to refrigerated storage imme-
diately to minimize degradative and oxidative reactions. The
products are replaced on a first-in/first-out basis, and the inven-
tory on a weekly basis. Currently MPR include the following
items: ready-to-eat fruits and vegetables, ready-to-cook fruits
and vegetables, ready-to-cook mixed meals, and fresh ready-to-
use herbs and sprouts.Quality of MPRConsumers expect fresh-cut products to be of optimum matu-
rity, without defects, and in fresh condition. The most important
physicochemical quality parameters targeted for preservation
include good appearance, nutrients, and excellent sensory at-
tributes such as texture, firmness, and taste. Minimally processed
products are vulnerable to discoloration because of damaged
cells and tissues that become dehydrated. Cutting and slicing of
carrots with a very sharp blade reduces the amount of damaged
cells and dehydration, when compared with those sliced with
a regular culinary knife. To overcome the problem with dehy-
dration, fresh-cut produce can be treated with calcium chloride
and kept in a high humidity atmosphere. Enzymatic browning
is a serious problem with minimally processed produce. During
the processing of produce, several types of oxidative reactions
may occur, leading to the formation of oxidized products. These
reactions cause browning reactions resulting in the loss of nu-
tritional value by the destruction of vitamins and essential fatty
acids. In lipid-rich vegetables, oxidative processes lead to the de-
velopment of rancid off-flavors and sometimes to toxic oxidative
products (Dziezak 1986). There are a number of chemicals used
to stabilize MPR produce including: (a) free radical scavengers
such as tocopherols; (b) reducing agents and oxygen scavengers
such as ascorbic acid and erythorbic acid; (c) chelating agents
such as citric acid, and (d) other secondary antioxidants such as
carotenoids. Ascorbic acid is commonly used either alone, or in
combination with other organic acids. Temperature is the most
important factor that influences the general quality of MPR pro-
duce. When temperature increases from 0◦Cto10◦C, respiration
rate increases substantially, with Q 10 (fold increase in respira-
tionbya10◦C increase in temperature) ranging from 3.4 to 8.3
among various fresh-cut products. With the increase in respira-
tion rate, deterioration rate also increases at a comparable rate;
therefore, low temperature storage is essential for maintaining
good quality (Watada et al. 1996). MA within MPR container
or bags is useful in keeping the quality of the produce (Gorny
1997). Gas mixtures suitable for MA storage have been the same
as those recommended for the whole commodity (Saltveit 1997).
CA system is used to simulate the MA with similar gas com-
position. A mixture of 10% O 2 +10% CO 2 has been shown
to retard chlorophyll degradation in parsley and broccoli florets
(Yamauchi and Watada 1993, 1998). An atmosphere of 3% O 2
+10% CO 2 was beneficial for fresh-cut iceberg lettuce, slightlybeneficial for romaine lettuce, and not beneficial for butterhead
lettuce (Lopez-Galvez et al. 1996). The oxygen level can be
allowed to drop to the level of respiratory quotient breakpoint.
The O 2 level could be dropped to 0.25% for zucchini slices
(Izumi et al. 1996), and 0.8% for spinach (Ko et al. 1996). Other
technologies that involve inactivation of ethylene action using
1-Methylcyclopropene (Lurie and Paliyath 2008), or controlling
gas movements using edible coating technologies (Fallik 2008)
are also being employed increasingly.FURTHER READING
Arthey D, Ashwurst PR. 2001.Fruit Processing: Nutrition, Products
and Quality Management. Aspen Publishers, Gaithersburg, MD,
p. 312.
Enachescu DM. 1995.Fruit and Vegetable Processing.FAOAgri-
cultural Services Bulletin 119. FAO, Rome, p. 382.
Jongen WMF. 2002.Fruit and Vegetable Processing: Improving
Quality (Electronic Resource). CRC Press, Boca Raton, FL.
Paliyath G et al. 2008.Postharvest Biology and Technology of Fruits,
Vegetables and Flowers. Wiley-Blackwell, Iowa, p. 482.
Salunkhe DK, Kadam SS. 1998.Handbook of Vegetable Science and
Technology: Production, Composition, Storage and Processing.
Marcel Dekker, New York, p. 721.REFERENCES
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