QUALITY ASSURANCE OF HARVESTED HORTICULTURAL PERISHABLES

Abstract

An effective quality assurance (QA) system throughout the handling steps between harvest and retail display is essential to provide a consistently good-quality supply of fresh horticultural crops to the consumers and to protect the reputation of a given marketing label. QA starts with the selection of the genotype and its proper time to harvest for the best appearance, textural, flavor (taste and aroma), and nutritional (including phytonutrients) quality. Careful harvesting and handling are required to minimize physical injuries. Each postharvest handling step has the potential to either maintain or reduce quality and in a few cases (such as ripening of climacteric fruits) improve eating quality. The availability of low-cost microcomputers and solid-state imaging systems have resulted in increased use of computer-aided video inspection to sort many products into two or more quality grades before marketing. Objective and nondestructive methods of differentiating horticultural perishables on the basis of their flavor and nutritional quality are being tested and will become excellent QA tools as they become more reliable and efficient. Safety assurance can be part of QA and its focus is on minimizing chemical and microbial contamination during production, harvesting, and postharvest handling of intact and fresh-cut fruits and vegetables. Future research and development efforts should focus on developing better methods of monitoring quality and safety attributes of fresh produce as part of a QA system. 1. Quality attributes Quality of fresh produce includes appearance (size, shape, color, gloss, and freedom from defects and decay), texture (firmness, crispness, juiciness, mealiness, and toughness, depending on the commodity), flavor (sweetness, sourness (acidity), astringency, aroma, and off-flavors), and nutritive value (vitamins, minerals, dietary fiber, phytonutrients). The relative importance of each quality component depends on the commodity and the individual’s interest (Kader, 1992). Most postharvest researchers, producers, and handlers are product-oriented in that quality is described by specific attributes of the product itself, such as sugar content, color, or firmness. In contrast, consumers, marketers, and economists are more likely to be consumer-oriented in that quality is described by consumer wants and needs (Shewfelt, 1999). Although consumers purchase fresh produce based on appearance and textural quality, their repeat purchases depend upon their satisfaction with flavor (taste and aroma). They are also interested in the health-promoting attributes and nutritional quality of fresh fruits and vegetables (Kader, 1988). Several attempts have been made to develop portable instruments with sensors that detect volatile production by fruits as a way to detect maturity and quality. Other strategies include the removal of a very small amount of fruit tissue and measurement of total sugars or soluble solids content. Near-infrared detectors have great potential for nondestructive estimation of sugar content in fruits (Abbott, 1999). Until such methods become widely available, we will continue to depend on destructive techniques, such as soluble solids determination by a refractometer and titratable acidity measurement by titration, to evaluate flavor quality of fruits. Table 1 summarizes the proposed minimum