Flavor and Color of Fruits as Affected by Processing

Abstract

Flavor and color are critical factors in the evaluation of fruit products. Color and other appearance defects may cause a consumer to reject a product before tasting it, or more subtly, the appearance of a product may change flavor perception. If appearance is acceptable, flavor is the primary sensory characteristic used in judging the quality of fruit products. Thus, any fruit processor must be aware of the role of color and flavor in product quality and the controlling factors in maintaining these characteristics.Although processors may have little or no control over a fruit crop before it is harvested, several factors contribute to product yield and quality. Cultivar, weather conditions, spraying schedules, and cultural techniques are all important. The time between picking and the first step in the processing plant is known as the postharvest period. Since most postharvest changes in quality of fruit for processing are undesirable, this is an area of concern. As a general rule, once quality is lost during a process it can never be recaptured. Prudent postharvest management of the raw product can payoff in final product yield and quality.Postharvest quality changes in fruits are the result of normal metabolic processes and physiological responses to stress. When viewed from a IThis chapter prepared for first edition by the late A. Lome Shewfelt Commercial Fruit Processing, 2nd Edition

The Effects of Thermal and Nonthermal Processing Methods on Apple Cider Quality and Consumer Acceptability

“…In addition, the pasteurized cider was measured in the green region (– a ), while the other samples were measured in the red region (+ a ). Shewfelt (1986) found that thermal treatments quickly degrade anthocyanins, which are found in apples and could have caused the shift of the pasteurized cider sample from the red region (+ a ) to the green region (– a ). The samples were all significantly different for b ‐values, but there were no noticeable trends.…”

“…Thermal processing also can greatly affect the cider color due to changes in the large polyphenol and pigment concentration. For instance, of the pigments found in apples, chlorophyll is degraded to pheophytins, carotenoids are converted to expoxids and anthocyanins are quickly degraded (Shewfelt 1986).…”

The Effect of Different Chemical Agents on the Prevention of Enzymatic Browning in Banana

“…This type of browning discoloration not only reduces the shelf life of several processed foods, but also negatively impacts the quality of frozen fruits and vegetables [1,2]. Because of enzymatic browning almost half of tropical fruits are discarded because of the quality defects [3].…”

Violet-red discolouration of canned Palmyra palm during processing

“…Nevertheless, Wu and Fang (1993) investigated the addition of citric acid mixed with 0.2 % polyphosphate in a sugar solution concentration of 30 o Brix to canned lychee and found that it could perk up instead of hinder the pink discolouration in the canned product. Shewfelt (1975); Cheng and Hwang (1986) and Somseang (2007) found that lychee flesh immersed in 0.2 % bisulfite solution successfully inhibited the activity of polyphenol oxidase and therefore prevented the pink discolouration in canned lychee. However an excess amount of sodium bisulfite caused the white, pale abnormal colour and taste in canned lychee.…”