مقاله انگلیسی Post harvest of horticultural crops

مقاله انگلیسی Post harvest of horticultural crops

اسلاید 1: بسم الله الرحمن الرحیم

اسلاید 2: نام استاد:تهیه کننده: رشته:

اسلاید 3: Post harvest of horticultural cropsPost harvest handling systems:Under ground vegetables(roots,tubers and bulbs)

اسلاید 4: Fresh-cut products have grown rapidly during the past decade, extend ing from the foodservice sector to the retail shell. These fruit and veg elable products are prepared and handled to maintain their fresh state while providing convenience to the user. Although more expensive than bulk produce on a weight basis, successful fresh-cut products are often more cost-effective for the user due to reduced waste. Minimal processing al central facilities greatly reduces the number of on-site employees involved in fresh produce preparation. Preparation of fresh cut products involves cleaning, washing, trimming, coring, slicing, shredding, and other related steps, many of which increase the per ishability of the produce items. Other terms used to refer to fresh-cui products are “minimally processed, lightly processed, partially processed, fresh-processed, and pre-prepared

اسلاید 5: Examples of fresh-cut vegetables include peeled and sliced pota toes, shredded lettuce and cabbage, mixed salads (fig. 36.1), washed and trimmed spinach, peeled baby carrots (fig.36.2). cauliflower and broccoli florets, and cleaned and diced onions. These products are expected to have a shelf life of 10 to 14 days and represent about 70% Marita I. Cantwell and of the total volume of fresh-cut items available commercially. Otherimportant vegetable items include peeled garlic (fig. 36.3), fresh sal Trevor V. Suslowsas, vegetable snacks such as carrots and celery, sliced mushrooms, sliced and diced tomatoes and peppers, and fresh or microwaveable vegetable trays

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اسلاید 9: recent fresh-cut vegetable products include salad meals or home replacement meals, which contain mcal and other lood items. Fresh-cut fruit products include peeled and cored pincapple; peeled citrus fruits (fig. 36.4) and segments; apple (fig. 36.5), peach, mango, and melon (lig. 36.6) slices; and fruit salads, Expected shelf life of these products is generally much less than for the vegetable products. Sales of fresh-cut products currently account for 8 to 10% of the fresh fruits and vegetables marketed through lood service and retail channels in the United States (see chapter 2).

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اسلاید 13: Whereas most food processing techniques stabilize the products and lengthen their storage and shell life, minimal processing of fruits and vegetables increases their perishability. Although the industry began as a salvage operation to utilize ofl-grade and second-harvest products, it was soon recognized that high-quality raw materials were required because of the increased perishability caused by product preparation. Due to this and the need for suici sanitation, preparation and handling of these products require an integration of production, postharvest, and food science technologies and marketing expertise

اسلاید 14: Fresh-cut or minimally processed products are also referred to as lightly processed, partially processed, fresh-processed, and pre-prepared. Examples of minimally processed vegetables include peeled and sliced potatoes, shredded lettuce and cabbage, mixed salads, washed and trimmed spinach, “baby” carrots, cauliflower and broccoli florets, cleaned and diced onions. These products are expected to have a shelf-life of 10-14 days, and represent about 70% of the total volume of fresh-cut items available commercially

اسلاید 15: . Other important vegetable items include peeled garlic, fresh salsas, vegetable snacks such as carrots and celery, sliced mushrooms, sliced and diced tomatoes and peppers, and fresh or microwaveable vegetable trays. More recent fresh-cut vegetable products include salad meals or “home replacement meals” which contain meat and other food items. Fresh-cut fruit products include peeled and cored pineapple, peeled citrus fruits and segments, slices of apple, peach, mango, and melon, and fruit salads. Expected shelf-life of these products is generally much less than for the vegetable products. Whereas most food processing techniques stabilize the products and lengthen their storage and shelf life, fresh-cut processing of fruits and vegetables increases their perishability

اسلاید 16: Although the industry began as a salvage operation to utilize off-grade and second harvest products, it was soon recognized that high quality raw materials were required because of product perishability. Due to this and the need for strict sanitation, preparation and handling of these products require an integration of production, postharvest, and food science technologies and marketing expertise.(California;Cantwell and Suslow 2002)

اسلاید 17: FRESH-CUT PRODUCT PHYSIOLOGY AND SHELF LIFE IMPLICATIONS

اسلاید 18: Fresh-cut products generally have higher respiration rates than the corresponding intact products. Higher respiration rates indicate a more active metabolism and, usually, a faster deterioration rate. Higher res piration rates can also result in more rapid loss of acids, sugars, and other components that determine flavor quality and nutritive value. The increased O demand due to the higher respiration rates of fresh cut products dictates that packaging films with sufficient permeability to O, are required to prevent fermentation and off-odors. The physical damage or wounding caused by preparation increases respiration and ethylene production within minutes, with associated increases in rates of other biochemical reactions responsible for changes in color

اسلاید 19: Strict temperature control is required to minimize the increased respiration rates of fresh-cut products. This is illustrated with data from intact and shredded cabbage stored at different temperatures (Fig. 1). Young leaf tissue will have higher respiration rates than mature fully developed leaves (Table 1). Salad size (2 x 2 cm) pieces from mature leaves have respiration rates almost double those of the intact leaves, but similar to rates of the small leaves. Shredding mature leaves approximately doubled respiration rates. Different parts of a vegetable may have very different respiration rates as illustrated with data from broccoli (Fig. 2). These differences have implications for the quality and shelf-life of mixed medleys and salads mixes. The quality of an entire fresh-cut item is only as good as that of its most perishable component. In mixed salads, it is important to ensure that “color” or “flavor” components be as fresh as possible and similar in shelf-life to the major components.(California;Cantwell and Suslow 2002)

اسلاید 20: Retail bags of mixed European salads from five major U.S. processors. Peeled orange fruits in rigid tray with film lid. Figure 36.5 Apple slices treated with browning inhibitors in a Fres Hold package. Figure 36.2 Baby carrots packaged in polyethylene bags for retail. Carrots in the bag on the left show surface drying or white blush.

اسلاید 21: Figure 36.6 Melon chunks and single-serving mixed fruit salads. 30 LBS. NET WERDE PRODUCE OF U.S.A 13.5 K NET THE CARLIC COMPANY FINEST GARLIC SHAFTER, CA 93263 Box 607 SHAFTER, CA., PHONE: 805-746-3935 30 LBS. NET 13,5 kg NET - PRODUCE OF 1.5.A. Figure 36.7 Respiration rates of intact and shredded cabbage stored at four tempera tures.

اسلاید 22: Shredded cabbage Respiration (ml CO2-kg.--) ► 00 Intact cabbage-- 2.5°C (36°F) - - 5°C (41°F) A 7.5°C (45°F) v 10°C (50°F) 25 Respiration (mL CO2 kg-.-) 100+ N001 <DO KO+ LAND A

اسلاید 23: bolic rates of fresh-cut products. The impor tance of temperature is illustrated with data from intact and shredded cabbage stored at different temperatures (fig. 36.7). Young leal tissue will have higher respiration rates than mature fully developed leaves, as shown with data on kale leaves (table 36.1). Salad-size (2 by 2 cm, or 0.75 by 0.75 in) pieces from mature kale leaves have respiration rates almost double those of the intact leaves, but their rates are similar to rates of the small leaves; shredding mature leaves approximate ly doubled respiration rates. Different parts of a vegetable may have very different respi ration rates, as illustrated by data from broc coli (fig. 36,8).

اسلاید 24: These differences in respira Lion rates have implications for the quality and shelf life of mixed medleys and salad mixes. The quality of an entire fresh-cut item is only as good as that of its most perishable component. In mixed salads, it is important to ensure that components included for their color or flavor qualities be as fresh as possi ble and similar in shelf life to the major salad components. These considerations also apply to a product such as cleaned and washed spinach, where differences in leaf age or physical damage may yield a mixed product of variable perishability.

اسلاید 25: The greater the degree of processing, the higher the induced rates of respiration. Intact garlic bulbs have relatively low respiration rates, but they have high respiration rates when cloves are peeled or chopped, especial ly is stored at temperatures above 5°C (41°F) (table 36.2). The respiration rates of iceberg and romaine lettuces cut as salad pieces (2 to 3 cm 2 to 3 cm, or 0.75 to 1.18 in by 0.75 to 1.18 in) are only 20 to 40% higher than rates of the respective intact heads. The respira tion rates of shredded lettuce and shredded cabbage are 200 to 300% greater than those of the intact heads and remain high through out the storage period (sec fig. 36.7). The relationship between respiration rates and changes in quality at different temperatures can be illustrated by data from intact and sliced mushrooms (fig. 36.9).

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اسلاید 27: Respiration rates and deterioration rates can be mini mized by quickly cooling the product and storing at 5°C (41°F) or below: Cutting carrots into large segments does not significantly change their respiration rate but does make them much more sensitive to ethylene

اسلاید 28: Fresh-cut fruits generally have a more complicated physiology than fresh-cut vegetables. Stage of ripeness at the time of processing may alter the physiological responses to cutting. In cantaloupe melon, respiration rates of pieces from fruit harvested at different stages of ripeness were similar. Ethylene production rates, however, are much higher in pieces from riper fruits (¾ or full slip) than less ripe fruit (¼ to ½ slip). Piece size will also greatly affect the physiological response of the fresh-cut fruits. Cantaloupe cut into very small pieces (0.2 mm) had a large increase in ethylene production, whereas large pieces (1 x 2 cm) were not different in their physiology from the intact fruit. Respiration rates of sliced peaches, bananas, kiwifruit and tomatoes average about 65% higher than rates of the corresponding intact fruits at 0-10°C (32-50°F).(Caliornia; Cantwell and Suslow 2002)

اسلاید 29: Table 36.1. Respiration rates of leaves of kale stored at various temper atures for 5 days Respiration rate (ml CO2-kg-h) 0°C 5°C 10°C 15°C Product (32°F) (41°F) (50°F) (59°F) Full-sized leaves 12 33 Small leaves 21 42 Chopped (pieces 2 by 2 cm 15 46 53 [4 by 4 in cut from full-sized leaves) Shredded (pieces 0.3 cm 17 68 [o in) from full-sized leaves) 29