Wheat drying

Giner, S.A. and Calvelo, A., Modelling of wheat drying in fluidized beds,... 

Gong, Z.-X., Devahastin, S., and Mujumdar, A.S. 1997. A two-dimensional finite element model for wheat drying in a novel rotating jet spouted bed. Drying Technology—An International Journal 15 575-592. 

The wheat drying studies were carried out in a spouted bed predryer of rectangular cross section equipped with a draft tube, and also in a cylindrical afterdryer (Tables 15.1 and 15.2). The experimental conditions and the data of the... 

The crop is harvested in August, as for wheat. Drying and storage advice is also the same as for wheat. 

The primary adhesive used ia hardwood plywood is urea—formaldehyde (UF) mixed with wheat flour as an extender to improve spreadabiUty, reduce penetration, and provide dry-out resistance. A catalyst may also be added to UF resias to speed the cure or to cause the UF to cure. Scavengers also may be added to reduce formaldehyde emissions from finished panels. If more water-resistance is requited using a UF bond, small amounts of melamine maybe added, producing a melamine—urea—formaldehyde (MUF) adhesive. 

The first pet food, a baked mixture of meat, vegetables, and wheat flour, was produced in the late 1800s. Early canned dog foods were composed mostly of meat from horses or dead stock. In the 1950s, high quaUty, nutritionally balanced, oven-baked, and pelleted dog foods became popular with dog owners and provided the most economical and satisfactory sources of dog nutrition. The extmsion process for pet foods was developed in 1954 and by 1957 extmded dog food had become the nation s leading dry pet food. 

Foods high ia sucrose, proteia, or starch (qv) tend to biad water less firmly and must be dried to a low moisture content to obtain microbial StabiHty. For example, grain and wheat flour can support mold growth at moisture contents above 15% (wet basis) and thus are stored at moisture contents below 14%. Stored grains and oil seeds must be kept at a water activity below 0.65 because certain molds can release aflatoxias as they grow. Aflatoxins are potent carciaogens (see Food toxicants, naturally occurring). 

A report on the continuous flash pyrolysis of biomass at atmospheric pressure to produce Hquids iadicates that pyrolysis temperatures must be optimized to maximize Hquid yields (36). It has been found that a sharp maximum ia the Hquid yields vs temperature curves exist and that the yields drop off sharply on both sides of this maximum. Pure ceUulose has been found to have an optimum temperature for Hquids at 500°C, while the wheat straw and wood species tested have optimum temperatures at 600°C and 500°C, respectively. Organic Hquid yields were of the order of 65 wt % of the dry biomass fed, but contained relatively large quantities of organic acids. 

A wide variety of special malts are produced which impart different flavor characteristics to beers. These malts are made from green (malt that has not been dried) or finished malts by roasting at elevated temperatures or by adjusting temperature profiles during kilning. A partial Hst of specialty malts includes standard malts, ie, standard brewers, lager, ale, Vienna, and wheat caramelized malts, ie, Munich, caramel, and dextrine and roasted products, ie, amber, chocolate, black, and roasted barley. 

Protein-Based Substitutes. Several plant and animal-based proteins have been used in processed meat products to increase yields, reduce reformulation costs, enhance specific functional properties, and decrease fat content. Examples of these protein additives are wheat flour, wheat gluten, soy flour, soy protein concentrate, soy protein isolate, textured soy protein, cottonseed flour, oat flour, com germ meal, nonfat dry milk, caseinates, whey proteins, surimi, blood plasma, and egg proteins. Most of these protein ingredients can be included in cooked sausages with a maximum level allowed up to 3.5% of the formulation, except soy protein isolate and caseinates are restricted to 2% (44). 

In industrial production of acid-modified starches, a 40% slurry of normal com starch or waxy maize starch is acidified with hydrochloric or sulfuric acid at 25—55°C. Reaction time is controlled by measuring loss of viscosity and may vary from 6 to 24 hs. For product reproducibiUty, it is necessary to strictly control the type of starch, its concentration, the type of acid and its concentration, the temperature, and time of reaction. Viscosity is plotted versus time, and when the desired amount of thinning is attained the mixture is neutralized with soda ash or dilute sodium hydroxide. The acid-modified starch is then filtered and dried. If the starch is washed with a nonaqueous solvent (89), gelling time is reduced, but such drying is seldom used. Acid treatment may be used in conjunction with preparation of starch ethers (90), cationic starches, or cross-linked starches. Acid treatment of 34 different rice starches has been reported (91), as well as acidic hydrolysis of wheat and com starches followed by hydroxypropylation for the purpose of preparing thin-hoiling and nongelling adhesives (92). 

Employing wood chips, Cowan s drying studies indicated that the volumetric heat-transfer coefficient obtainable in a spouted bed is at least twice that in a direct-heat rotaiy diyer. By using 20- to 30-mesh Ottawa sand, fluidized and spouted beds were compared. The volumetric coefficients in the fluid bed were 4 times those obtained in a spouted bed. Mathur dried wheat continuously in a 12-in-diameter spouted bed, followed by a 9-in-diameter spouted-bed cooler. A diy-ing rate of roughly 100 Ib/h of water was obtained by using 450 K inlet air. Six hundred pounds per hour of wheat was reduced from 16 to 26 percent to 4 percent moisture. Evaporation occurred also in the cooler by using sensible heat present in the wheat. The maximum diy-ing-bed temperature was 118°F, and the overall thermal efficiency of the system was roughly 65 percent. Some aspec ts of the spouted-bed technique are covered by patent (U.S. Patent 2,786,280). 

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