ASHRAE REFRIGERATION SI CH 21-2010 COMMODITY STORAGE REQUIREMENTS《商品存储要求》.pdf
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1、21.1CHAPTER 21COMMODITY STORAGE REQUIREMENTSRefrigerated Storage . 21.1Refrigerated Storage Plant Operation 21.10Storage of Frozen Foods. 21.11Other Products 21.11HIS chapter presents information on storage requirements ofTmany perishable foods that enter the market on a commercialscale. Also includ
2、ed is a short discussion on the storage of furs andfabrics. The data are based on the storage of fresh, high-quality com-modities that have been properly harvested, handled, and cooled.Tables 1 and 2 present recommended storage requirements forvarious products. Some products require a curing period
3、before stor-age. Other products require different storage conditions, dependingon their intended use.The recommended temperatures are optimum for long storageand are commodity temperatures, not air temperatures. For shortstorage, higher temperatures are often acceptable. Conversely, prod-ucts subjec
4、t to chilling injury can sometimes be held at a lower tem-perature for a short time without injury. Exceptions include bananas,cranberries, cucumbers, eggplant, melons, okra, pumpkins, squash,white potatoes, sweet potatoes, and tomatoes. The minimum recom-mended temperature for these products should
5、 be strictly followed.The listed storage lives are based on typical commercial practice.Special treatments can, in certain instances, extend storage life sig-nificantly.Thermal properties of many of these products, including watercontent, freezing point, specific heat, and latent heat of fusion, are
6、listed in Chapter 19. Also, because fresh fruits and vegetables areliving products, they generate heat that should be included as part ofthe storage refrigeration load. The approximate heat of respirationfor various fruits and vegetables is also listed in Chapter 19.REFRIGERATED STORAGECoolingBecaus
7、e products deteriorate much faster at warm than at lowtemperatures, rapid removal of field heat by cooling to storage tem-perature substantially increases the products market life. Chapter28 describes various cooling methods.DeteriorationThe environment in which harvested produce is placed maygreatl
8、y influence not only the respiration rate but also other changesand products formed in related chemical reactions. In fruits, thesechanges are described as ripening. In many fruits, such as bananasand pears, the process of ripening is required to develop the maxi-mum edible quality. However, as ripe
9、ning continues, deteriorationbegins and the fruit softens, loses flavor, and eventually undergoestissue breakdown.In addition to deterioration after harvest by biochemical changeswithin the product, desiccation and diseases caused by microorgan-isms are also important.Deterioration rate is greatly i
10、nfluenced by temperature and isgenerally reduced as temperature is lowered. The specific relation-ships between temperature and deterioration rate vary considerablyamong commodities and diseases. A generalization, assuming anominal deterioration rate of 1 for a fruit at 1C, is as follows:For example
11、, fruit that remains marketable for 12 days when storedat 1C may last only 12/3 = 4 days when stored at 5C. The besttemperature to slow down deterioration is often the lowest temper-ature that can safely be maintained without freezing the commodity,which is 0.5 to 1 K above the freezing point of the
12、 fruit or vegetable.Some produce will not tolerate low storage temperatures. Severephysiological disorders that develop because of exposure to low butnot freezing temperatures are classed as chilling injury. The bananais a classic example of a fruit displaying chilling injury symptoms,and storage te
13、mperatures must be elevated accordingly. Some applevarieties exhibit this characteristic, and prolonged storage must beat a temperature well above that usually recommended. An applevarietys degree of susceptibility to chilling may vary with climaticand growing factors. Products susceptible to chilli
14、ng injury, itssymptoms, and the lowest safe temperature are discussed in Chap-ters 19 and 35 to 37.DesiccationWater loss, which causes a product to shrivel, is a physical factorrelated to the evaporative potential of air, and can be expressed asfollows:wherepD= vapor pressure deficit, indicating com
15、bined influence of temperature and relative humidity on evaporative potential of airp = vapor pressure of water at given temperature = relative humidity, percentFor example, comparing the evaporative potential of air in stor-age rooms at 0C and 10C db, with 90% rh in each room, thevapor pressure def
16、icit at 0C is 60 Pa, whereas at 0C it is 120 Pa.Thus, if all other factors are equal, commodities tend to lose watertwice as fast at 0C db as at 0C at the same relative humidity. Forequal water loss at the two temperatures, the rh has to be main-tained at 95% at 10C to 90% at 0C. These comparisons a
17、re notprecise because the water in fruits and vegetables contains a suf-ficient quantity of dissolved sugars and other chemicals to causethe water to be in equilibrium with water vapor in the air at 98 to99% rh instead of 100% rh. This property is described by the wateractivity awof the product. Low
18、ering the vapor pressure deficit bylowering the air temperature is an excellent way to reduce waterloss during storage.The preparation of this chapter is assigned to TC 10.5, Refrigerated Distri-bution and Storage Facilities.Approximate Deterioration Rate of Fresh ProduceTemperature, C Relative Dete
19、rioration Rate20 8 to 1010 4 to 5533201.251 1pDp 100 100-=21.2 2010 ASHRAE HandbookRefrigeration (SI)Table 1 Storage Requirements of Vegetables, Fresh Fruits, and MelonsCommon Name(Other Common Name)ScientificNameStorageTemp.,CRelativeHumid-ity, %HighestFreezing Temp.,CEthyleneProductionRateaEthylen
20、e SensitivitybRespi-rationRatecApproximatePostharvestLifeObservationsand BeneficialCAdConditionsAcerola (Barbados cherry) Malpighia glabra 0 85 to 90 1.4 6 to 8 weeksAfrican horned melon (kiwano)Cucumis africanus 13 to 15 90 Low Moderate 3 to 6 monthsAmaranth (pigweed) Amaranthus spp. 0 to 2 95 to 1
21、00Very low Moderate 10 to 14 daysAnise (fennel) Foeniculum vulgare 0 to 2 90 to 95 1.1 2 to 3 weeksAppleNot chilling sensitive Malus pumila 1 90 to 95 1.5 Very high High Low 3 to 6 months 2 to 3% O21 to 2% CO2Chilling sensitive Malus pumila cv.Yellow Newton, Grimes golden, McIntosh4 90 to 95 1.5 Ver
22、y high High Low 1 to 2 months 2 to 3% O21 to 2% CO2Apricot Prunus armeniaca 0.5 to 0 90 to 95 1.1 Moderate Moderate Low 1 to 3 weeks 2 to 3% O22 to 3% CO2ArtichokesChinese Stachys affinia 0 90 to 95 Very low Very Low 1 to 2 weeksGlobe Cynara acolymus 0 95 to 1001.2 Very low Low High 2 to 3 weeks 2 t
23、o 3% O23 to 5% CO2Jerusalem Helianthus tuberosus0.5 to 0 90 to 95 2.5 Very low Low Low 4 monthsArugula Eruca vesicaria var. sativa095 to 100Very low High Moderate 7 to 10 daysAsian pear (nashi) Pyrus serotinaP. pyrifolia1 90 to 95 1.6 High High Low 4 to 6 monthsAsparagus, green or white Asparagus of
24、ficinalis2.5 95 to 1000.6 Very low Moderate Very high 2 to 3 weeks 5 to 12% CO2Atemoya Annona squamosa xA. cherimola13 85 to 90 High High 2 to 4 weeks 3 to 5% O25 to 10% CO2AvocadoFuchs, Pollock Persea americanacv. Fuchs, Pollock13 85 to 90 0.9 High High Moderate 2 weeksFuerte, Hass Persea americana
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