Maturity, Ripening, and Quality Relationships 61
There is limited information in regard to flavor retention of vegetables in
storage. Sugar content of carrots increased with harvest maturity, as did the
sucrose:reducing sugar ratio, and these differences were maintained during cold
storage (Fritz and Weichmann, 1979). In fresh-cut product, maturity of the raw
vegetable can have an effect on the subsequent flavor retention over its shelf life.
For example, fully colored, mature peppers maintained higher sugar content and
better flavor than immature green peppers after they were fresh-cut into slices
(López-Gálvez et al., 1997).
3.2.3 NUTRITIONAL QUALITY
Discussion regarding nutritional quality will focus on the vitamin and antioxidant
content of fruits and vegetables. While this is a relatively new area of research
investigation, results are interesting and are worthy of discussion and perhaps future
research initiatives.
Ascorbic acid (vitamin C) is a water-soluble vitamin of great importance to the
general nutritive quality of fruits and vegetables (Yahia et al., 2001). Ascorbic acid
contents of peppers, tomatoes, apricots, peaches, and papayas have been reported
to increase with more advanced maturity at harvest (Lee and Kader, 2000). In peppers
and tomatoes, it has been shown that ascorbic acid increases up to full coloration;
however, levels decline as the fruits are allowed to ripen beyond that stage (Soto-
Zamora et al., 2001; Yahia et al., 2001). Ascorbic acid levels generally decline with
harvest maturity for apples, mangoes, peas, and citrus (Lee and Kader, 2000). One
hypothesis put forward regarding the decline in ascorbic acid in citrus was that the
apparent content declines as the fruit increases in size, which suggests that the
increase in size dilutes the total ascorbic acid content. This is supported by the
observation that ascorbic acid per fruit remained constant with maturation of citrus
(Lee and Kader, 2000). Since ascorbic acid generally declines in storage (Lee and Kader,
2000), the content at harvest is an important determinant of the content on the retail
shelf. At all ripeness stages, the ascorbic acid content of fruit declined with increased
duration in storage (Soto-Zamora et al., 2001). Similar results were obtained when using
different maturities of mango in fresh-cut packages (Izumi et al., 2003).
Carotene is another important nutrient, at least partially due to its strong anti-
oxidant power (Giovanelli et al., 1999). It is a lipid-soluble nutrient and is found in
many fruits and vegetables, but it is probably highest in carrots (Salunkhe and Desai,
1984). The carotene content of carrots increased with harvest maturity, and this
difference was maintained during cold storage (Fritz and Weichmann, 1979). The
carotenoid (carotene and lycopene) content of tomatoes increased with the ripeness
of the fruit (Giovanelli et al., 1999). However, tomatoes harvested at the mature-
green stage developed a higher carotenoid (both carotene and lycopene) content than
those left to ripen on the vine (Giovanelli et al., 1999). This suggests that optimal
nutritional quality can be achieved in tomatoes if they are harvested at an early stage
of ripening (mature-green).
Antioxidant content is influenced by the maturity of the fruit. In the case of
peppers, the water-soluble antioxidant content increased with advancing ripeness