3c__Standardization_of_Quality - F r e s h - C u t P r o d...

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Unformatted text preview: F r e s h - C u t P r o d u c t s :M a i n t a i n i n g Q u a l i t y a n d S a f e t y Section 3c STANDARDTZNIONOF QTJALITY By Adel A. Kader and Beth Mitcham Quality of fresh-cut fruits and vegetables is a combination of attributes that determine their value as human food. These quality factors include visual appearance (freshness, color, defects, and decay), texture (crispness, turgidity, juiciness, firmness, toughness, and tissue integrity), flavor (taste and smell), nutritive value (vitamins A and C, minerals, and dietary fiber), and safety (absence of chemical residues and microbial contamination). Quality of the fresh cut products depends upon quality of the intact commodity and its maintenance until preparation, method of preparation, and subsequent handling conditions (speed of cooling, 2. Pre-harvest factors: Climatic conditions such as temperature and rainfall influence quality at harvest and length of postharvest-life since the effects of environmental stresses are cumulative. Cultural practices such as soil type, nutrient and water supply, pest management, and crop load affect the composition of the harvested plant part. Excess water supply, excess nitrogen, and low calcium are related to poor postharvest-life of fresh fruits and vegetables. Contact of the edible plant part with soil where un-sterilized organic fertilizers are used increases the potential for contamination with human pathogens. maintaining optimum temperature and relative humidity, expedited marketing, and proper sanitation). Fresh-cut operations should not be viewed as a way to utilize inferior quality, overmature, or defec- 3. Harvesting stage: Selecting the optimum maturity for each commodity is essential to providing the best combination of eating quality and postharvest-life. Vegetables picked at a point when tive commodities that can not be marketed intact. Only good quality intact fruits and vegetables and cultivars that are more suitable for preparation of cut products should be used in order to assure good quality for the consumer. they are still growing (such as broccoli, sweet corn, summer squash, and asparagus) have very high metabolic activity and small amounts of storage reserves, while those harvested mature (such as winter squash and potato) have low metabolic Factors Influencing Composition of Intact Commodities and Quality 1. Genetic factors: For many fruits and vegetables there are large differences among cultivars in composition and quality. For example, vitamin A content of carrots ranges from 8,500 to 19,500 IU per 100 grams and flesh browning potential varies greatly among apple and pear cultivars. Use of broccoli and cauliflower cultivars that form less compact heads may facilitate cutting the florets with less damage. It is possible that new cultivars with desired characteristics will be developed through plant breeding and biotechnology; examples include lower polyphenol oxidase activity (less browning of cut products), reduced activities of cell waII degrading enzymes (better firmness retention and less exudation of cell sap from cut products), and/or better flavor (higher sugars, lower acidity, more intense aroma, no off-flavors). activity and large amounts of storage reserves. Immature vegetables deteriorate much faster than mature vegetables. Stringiness and ribbiness of over mature cabbage, celery, and lettuce render them unsuitable for fresh-cut products. Fruits taste best when picked fully-ripe or nearly so, but these fruits may be too soft for a fresh-cut product. Compromises between optimum flavor and texture are often necessary. 4. Handling Maintaining between harvest and preparation: the quality of fresh fruits and veg- etables between harvest and preparation (peeling, cutting, etc.) depends upon care in handling (minimizing mechanical injuries), rapid cooling, maintenance of optimum temperature and relative humidity, and exclusion of ethylene from ethylene sensitive commodities. Fruits picked mature-green or partially-ripe should be ripened before cutting to ensure good eating quality. Fresh-Cut Products: Maintaining Quality and Safety Preparation Procedures Influence Quality of Signs of Deterioration Section 3c of Fresh-cut Products Cut Products 1. Cleaning: Thorough cleaning of the intact commodity (including use of chlorine to reduce microbial load) is essential to producing a clean cut product. The microflora of fresh cut fruits and vegetables may originate from pre-harvest contamination or from processing equipment. Thus, both the commodity and equipment used must be kept as clean as possible during preparation. Washing of the cut product removes tissue exudate, which can be a favorable substrate for microbial growth. 2. Cutting: Preparation of fresh-cut products involve wounding of the plant tissues which leads to increased rates of respiration, ethylene production, browning, water loss, and overall quality deterioration. The greater the wounding (such as cutting into smaller pieces), the shorter the post-preparation life of the product. For example, the post-cutting life of peeled and cut carrots is longer than that of sliced carrots, which is longer than that of grated carrots. Sharp knives (blades) will reduce product injury. Presence of off-size (large pieces for 3. Uniformity: the product) and/or inedible tissues (core pieces, roots, peels, etc.) detract from the quality of the cut product. 4. Packing: Proper packaging can help maintain quality of the cut products by reducing water loss and tissue browning. If packaging restricts gas diffusion too much, it is possible that oxygen depletion and/or accumulation of carbon dioxide can lead to fermentative metabolism and off-odor development. Factors Post-preparation Cooling and maintenance of optimum temperature [0"C (32"F) for most products] and relative humidity (95 to 98%) during transport, in temporary storage at destination wholesale and retail handling facilities, and during retail display are the most important factors in maintaining quality of cut products. Expedited handling (reducing the time between preparation and consumption) ensures good quality. Dating of fresh cut product packages (such as preparation date, sell by date, or best if used by date) is highly desirable. 1. Bruised or broken pieces resulting from packaging too tightly and/or rough handling. 2. Wilting, wrinkling, shrivelling, flabbiness, flacidity, and excessive drying due to water loss. 3. Mushiness resulting from excessive tissue softening. 4. Development of off-colors (yellow, red, tan, brown, or black discoloration) due to loss of chlorophyll (green color), enzymatic browning, and/or physiological disorders such as tip burn of lettuce. 5. Presence of free liquid within packages of freshcut products. This may be associated with sliminess and incidence of decay-causing pathogens (such as soft rot bacteria). 6. Presence of undesirable odors. such as fermented aroma due to accumulation of ethanol, acetaldehyde, and/or ethyl acetate; foul odor due to bacteria; or musty and molding smell due to fungi. 7. Bloated bags due to excess gas in sealed bags resulting from fermenting or decaying product. Nutritional Quality Wounding plant tissues can accelerate loss of vitamins, especially the water-soluble vitamin C. All the recommended procedures for maintaining overall quality of cut fruits and vegetables should help quality. Our data so far indicates that vitamins A and C losses in cut fruits become significant only after the products visual quality has deteriorated below the level of marketability. However more research is needed to quantify minimize loss of nutritional changes in nutrients due to cutting and identify procedures for reducing losses in nutritional quality during the time between preparation and consumption. Standardization and Inspection grade standards for fresh cut There are no U.S. products. However, the Fresh Products Branch of the USDA Agricultural Marketing Service, Fruit & Vegetable Division and the Fresh-cut Produce F r e s h - C u t P r o d u c t s :M a i n t a i n i n g Q u a l i t y a n d S a f e t y Industry developed inspection instructions that were published in November 1993then reprinted with a few revisionsin May 1994.These instructions provide guidelinesand definitions that can serve as a commonlanguagefor the Inspection Servicein the inspectionand certification of fresh-cut (ready-touse) products. [Copiesof this booklet (Fresh-cut produce:shipping point and market inspection instructions)can be purchased($tO per copy)from the USDA-AMS-Fruit & VegetablesDivision or from the International Fresh Cut ProduceAssociation] References: Brecht,J.K., 1995.Physiologyof lightly processed fruits and vegetables. HortScience30:L8-22. Section 3c Romig, W.R. 1995. Selection of cultivars for lightly processedfruits and vegetables. HortScience 30:3840 Shewfelt, R.L. 1987. Quality of minimally processed frui ts and vegetabl es.J. Food Qual i ty 10 : 143- 156 W atada, A .8., N .P . K o, and D .A . Mi nott. 1996. Factors affecting quality of fresh-cut horticultural products. P ostharv. B i ol . Technol . 9:115- 125 Wiley, R.C. (editor). t994 Minimally processed regfrigerated fruits and vegetables. Chapman Hall, New York, 368 p. ...
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This note was uploaded on 05/03/2009 for the course FST 160 taught by Professor Giovanni during the Winter '08 term at UC Davis.

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