ASHRAE REFRIGERATION IP CH 42-2010 CHOCOLATES CANDIES NUTS DRIED FRUITS AND DRIED VEGETABLES《巧克力、糖果、坚果、干果和干菜》.pdf

1、42.1CHAPTER 42CHOCOLATES, CANDIES, NUTS, DRIED FRUITS, ANDDRIED VEGETABLESCANDY MANUFACTURE. 42.1Milk and Dark Chocolate. 42.1Hand Dipping and Enrobing . 42.2Bar Candy 42.2Hard Candy 42.3Hot Rooms 42.3Cold Rooms 42.3Cooling Tunnels. 42.4Coating Kettles or Pans . 42.4Packing Rooms. 42.4Refrigeration

2、Plant. 42.4STORAGE. 42.5Candy . 42.5Nuts. 42.7Dried Fruits and Vegetables 42.7Controlled Atmosphere 42.8CANDY MANUFACTUREIR conditioning and refrigeration are essential for successfulAcandy manufacturing. Proper atmospheric control increasesproduction, lowers production costs, and improves product q

3、uality.Every plant has one or more of several standardized spaces oroperations, including hot rooms; cold rooms; cooling tunnels; coat-ing kettles; packing, enrobing, or dipping rooms; and storage.Sensible heat must be absorbed by air-conditioning and refrig-eration equipment, which includes the air

4、 distribution system,plates, tables, cold slabs, and cooling coils in tunnels or similarcoolers. In calculating loads, sensible heat sources such as people,power, lights, sun effect, transmission losses, infiltration, steamand electric heating apparatus, and the heat of the entering productmust be c

5、onsidered. See Chapter 24 for more information. Table 1summarizes the optimum design conditions for refrigeration andair conditioning.Two of the basic ingredients in candy are sucrose and corn syrup.These change easily from a crystalline form to a fluid, depending ontemperature, moisture content, or

6、 both. The surrounding tempera-ture and humidity must be controlled to prevent moisture gain orloss, which affects the products texture and storage life. Tempera-ture should be relatively low, generally below 70F. The relativehumidity should be 50% or less, depending on the type of sugar used.For ch

7、ocolate coatings, temperatures of 65F or less are desirable,with 50% rh or less.In processing areas where lower relative humidity and tempera-ture are required and production demands are high, serious consid-erationshouldbegiventousingASHRAEextremeconditionsasthedesign criteria for the air-handling

8、equipment.MILK AND DARK CHOCOLATECocoa butter is either the only fat or the principal fat in chocolate,constituting 25 to 40% or more of various types. Cocoa butter is acomplex mixture of triglycerides of high-molecular-weight fattyacids, mostly stearic, oleic, and palmitic. Because cocoa butter isp

9、resent in such large amounts in chocolate, anything affecting cocoabutter affects the chocolate product as well.Because cocoa butter is a mixture of triglycerides, it does not actas a pure compound. Its physical properties, melting point, solidifi-cation point, latent heat, and specific heat affect

10、the mixture. Cocoabutter softens over a wide temperature range, starting at about 80Fand melting at about 94F. It has no definite solidification point; thisvaries from just below its melting point to 80F or lower, dependingThe preparation of this chapter is assigned to TC 10.9, Refrigeration Appli-c

11、ation for Foods and Beverages.Table 1 Optimum Design Air ConditionsaDry-BulbTemperature, FRelativeHumidity, %Department or ProcessChocolate pan supply air 55 to 62 55 to 45Enrober room 80 to 85 30 to 25Single cooling tunnel 36 to 45 85 to 70Double cooling tunnelentering 50 to 55leaving 38 to 45Hand

12、dipper 62 45Molded goods cooling 36 to 45 85 to 70Chocolate packing room 65 50Chocolate finished stock storage 65 50Centers tempering room 75 to 80 35 to 30Marshmallow setting room 75 to 78 45 to 40Grained marshmallow(deposited in starch) drying110 40Gum (deposited in starch) drying 125 to 150 25 to

13、 15Sanded gum drying 100 25 to 40Gum finished stock storage 50 to 65 65Sugar pan supply air (engrossing) 85 to 105 30 to 20Polishing pan supply air 70 to 80 50 to 40Pan rooms 75 to 80 35 to 30Nonpareil pan supply air 100 to 120 20Hard candy cooling tunnel supply air 60 to 70 55 to 40Hard candy packi

14、ng 70 to 75 40 to 35Hard candy storage 50 to 70 40Caramel rooms 70 to 80 40Raw Material StorageNuts (insect) 45 60 to 65Nuts (rancidity) 34 to 38 85 to 80Eggs 30 85 to 90Chocolate (flats) 65 50Butter 20Dates, figs, etc. 40 to 45 75 to 65Corn syrupb90 to 100Liquid sugar 75 to 80 40 to 30Comfort air c

15、onditions 75 to 80 60 to 50Note: Conditions given are intended as a guide and represent values found to be satis-factory for many installations. However, specific cases may vary widely from thesevalues because of factors such as type of product, formulas, cooking process, methodof handling, and time

16、 Acceleration or deceleration of any of the foregoing changestemperature, humidity, or both to some degree.aTemperature and humidity ranges are given in respective order (i.e., first temperaturecorresponds to first humidity).bDepends on removal system. With higher temperatures, coloration and fluid

17、ity aregreater.42.2 2010 ASHRAE HandbookRefrigerationon the quantity and hardness of cocoa butter and the time it is held atvarious temperatures. The presence of milkfat in milk chocolatelowers both the melting point and the solidification point of thecocoa butter. High-quality milk chocolate remain

18、s fluid for easyhandling at temperatures as low as 86 to 88F. Sweet chocolateremains fluid as low as 90 to 92F.Chocolate can be subcooled below its melting point withoutcrystallization. In fact, it does not crystallize en masse but rather insuccessive stages, as solid solutions of a very unstable cr

19、ystallinestate are formed under certain conditions. The latent heat of crystal-lization (or fusion) is a direct function of the manner in which thechocolate has been cooled and solidified. Once crystallization hasstarted, it continues until completion, taking from several hours toseveral days, depen

20、ding on exposure to cooling, particularly to lowtemperatures (subcooling).The latent heat of solidification of the grades of chocolate com-monly used in candy manufacture varies from approximately 36 to40 Btu/lb. Average values for the specific heat of chocolate may betaken as 0.56 Btu/lbF before so

21、lidification and 0.30 Btu/lbFafter solidification. The average value for the specific heat of cocoabutter is 0.5 Btu/lbF; for milk chocolate, 0.484 Btu/lbF; and forroasted cocoa bean, 0.44 Btu/lbF. In calculating the cooling load,a margin of safety should be added to these figures.Cocoa butters cool

22、ing and solidification properties exist in fivepolymorphic forms: one stable form and four metastable or labileones. Cocoa butter usually solidifies first in one of its metastableforms, depending on the rate and temperature at which it solidifies.In solidified cocoa butter, the lower-melting labile

23、forms changerapidly to the higher-melting forms. The higher-melting labileforms change slowly, and seldom completely, to the stable form.Commercial chocolate blocks are cast in metal or plastic poly-carbonate molds after tempering. During this process, it is desir-able to cool the chocolate in the m

24、olds as quickly as possible, thusrequiring the shortest possible cooling tunnel. However, coolingblocks too quickly (particularly large commercial blocks, whichcan range from 10 to 50 lb) may cause checking or cracking,which, though not injurious to quality, adversely affects theblocks appearance an

25、d strength. Depositing chocolate into moldsat 85 to 90F is common.Dark chocolate should be cooled very slowly at 90 to 92F;milk chocolate, at 86 to 88F. Air entering the cooling tunnel,where the goods are unmolded, may be 40F. The air may be 62Fwhere the goods enter the tunnel. After the chocolate i

26、s depositedin the mold, it can be moved into a cooling tunnel for a continuouscooling process, or the molds can be stacked up and placed in acooling room with forced-air circulation. In either case, tempera-tures of 40 to 50F are satisfactory. The discharge room from thecooling tunnel or the room to

27、 which molds are transferred forpacking should be maintained at a dew point low enough to pre-vent condensation on the cooled chocolate. Load calculations forthe cooling or cold room must account for transmission and infil-tration losses, any load derived from further cooling of the molds,and the se

28、nsible and latent heat cooling loads of the chocolateitself.The tunnel is designed to introduce 40F air countercurrent to theflow of chocolate; the coldest air enters the tunnel where the cooledchocolate leaves the tunnel. Because the tunnel air warms on its wayout, the warmest air leaves the tunnel

29、 at the point where the warmestmolten chocolate enters. The leaving chocolate is markedly coolerthan the entering chocolate, and the subcooling is greatly reduced.This in turn reduces the large temperature difference between thechocolate and the cooling air along the entire tunnel length.For any par

30、ticular application, only testing will determine thelength of time the chocolate should remain in the tunnel and the sub-sequent temperature requirements. Good cooling is generally afunction of tunnel length, belt speed, and the actual time the productcontacts the cooling medium.HAND DIPPING AND ENR

31、OBINGThe candy centers of chocolate-coated candies are eitherformed by hand or cast in starch or rubber molds. They are thendipped by hand or enrobed mechanically. The chocolate supply forhand dipping is normally kept in a pan maintained at the lowesttemperature that still ensures sufficient fluidit

32、y for the process.Because this temperature is higher than the dipping room tempera-ture, a heat source, such as electrically heated dipping pans withthermostatic controls, is required. Dipped candy is placed either ontrays or on belts while the chocolate coating sets.Setting is controlled by conditi

33、oning the dipping room air. A dry-bulb temperature of 35 to 40F best promotes rapid setting and pro-vides a high gloss on the finished goods. However, the temperaturein the dipping room is raised for human comfort. Suggested condi-tions for hand-dipping rooms are 64F db and a relative humiditynot ex

34、ceeding 50 to 55%. The principal aim is to achieve uniform airdistribution without objectionable drafts. Loads for this room in-clude transmission, lights, and people, as well as heat load from thechocolate and heat used to warm dipping pans.In high-speed production of bar candy, the chocolate coati

35、ng isapplied in an enrober machine, which consists mainly of a heatedand thermostatically controlled reservoir for the fluid chocolate.This chocolate is pumped to an upper flow pan that allows it to flowin a curtain down to the main reservoir. An open chain-type belt car-ries the centers through the

36、 flowing chocolate curtain, where theypick up the coating. At the same time, grooved rolls pick up somechocolate and apply it to the bottom of the centers. Centers shouldbe cooled to 75 to 80F to help solidification and retention of theproper amount of coating.The coated pieces are transferred from

37、the enrober to thebottomer slab and then pass into the enrober cooling tunnel. Thefunction of the bottomer slab is to set the bottom coating as rapidlyas possible, to form a firm base for the pieces as they pass throughthe enrober tunnel. The bottomer slab is often a flat-plate heat ex-changer fed w

38、ith chilled water or propylene glycol or directly sup-plied with refrigerant. The belt carrying the candy passes directlyover this plate, and heat transfer must take place from the candythrough the belt to the surfaces of the bottomer slab. The bottomerslab is sometimes located before the enrober to

39、 create a good bottombefore full coverage.The enrober cooling tunnel sets the balance of the chocolatecoating as rapidly as is consistent with high quality and goodappearance of the finished pieces. Typical enrober cooling tunneltimes are approximately 7 to 8 min for milk chocolate, and can be aslow

40、 as 3 to 6 min for vegetable-fat-based coatings. The dischargeend of the enrober tunnel is normally in the packing room, where thefinished candy is wrapped and packed.Although not absolutely necessary, air conditioning the enrobingroom is desirable. Because the coating is exposed to the room atmo-sp

41、here, the atmosphere should be clean to prevent contamination ofthe coating with foreign material. It is advisable to maintain condi-tions of 75 to 80F db and 50 to 55% rh; that is, low enough to pre-vent centers from warming and to help set the chocolate after it isapplied.BAR CANDYProduction of ba

42、r candy calls for high-speed semiautomatic op-erations to minimize production costs. From the kitchen, the cen-ter material is either delivered to spreaders, which form layers ontables, or cast in starch molds. Depending on the composition ofthe center, the material may be delivered at temperatures

43、as high as160 to 180F. Successive layers of different color or flavor may bedeposited to build up the entire center. These layers usually consistof nougat, caramel, marshmallow whip, or similar ingredients, towhich peanuts, almonds, or other nuts may be added. Becauseeach ingredient requires a diffe

44、rent cooking process, each separateChocolates, Candies, Nuts, Dried Fruits, and Dried Vegetables 42.3ingredient is deposited in a separate operation. Thus, a 1/8 in.layer of caramel may be deposited first, then a layer of peanuts,followed by a 3/4 in. layer of nougat. Except for nuts, it is neces-sa

45、ry to allow time for each successive layer to set before the nextis applied. If the candy is spread in slabs, the slab must be cooledand then cut with rotary knives into pieces the size of the finishedcenter.HARD CANDYManufacturing hard candy with high-speed machinery requiresair conditioning to mai

46、ntain temperature and humidity. Candymade of cane sugar has somewhat different requirements from thatmade partly with corn syrup. For example, a dry-bulb temperatureof 75 to 80F with 40% rh is satisfactory for corn syrup (as the cornsyrup percentage increases, the relative humidity must decrease),wh

47、ereas the same temperature with 50% rh is satisfactory for canesugar.Where relative humidity is to be maintained at 40% or less, stan-dard dehydrating systems using chemicals such as lithium chloride,silica gel, or activated alumina should be used. A combination ofrefrigeration and dehydration is al

48、so used.The amount of air required is a direct function of the sensibleheat of the room. Approximate rules indicate that the quantityshould be between 1.5 and 2.5 cfm per square foot of floor area, witha minimum of 15% outdoor air, or 30 cfm per person. The sensibleheat in hard candy, which is at a

49、high temperature to keep it pliableduring forming, must also be taken into account.If concentrations of the finished product in containers or tubs arelocated in the general conditioned area, the quantity of air must beincreased to prevent the product from sticking to the container.Unitary air conditioners using dry coils are satisfactory if theyhave a sufficient number of rows and adequate surface. A centralstation apparatus using cooling and dehumidifying coils of similardesign may also be used. Good filtration is essential for air purity aswell as for preve