Half-Products or Pellets

This category is one of the most popular among breakfast cereals. Many wheat and oat-based breakfast cereals such as Cheerios, Kix, and Alpha Bits are manufactured 

Most pellets are first cooked in an extruder and then formed using a second unit. The aim is to produce a cooked peUet with high density that is further dehydrated to yield an intermediate shelf-stable product. After drying, pellets can be stored for long periods of time, or after a small tanpering or equilibration time, they can be processed into final products. Generally, pellets are gun-puffed to yield final products. 

Half-products, in contrast to direct expanded collets, offer the advantage of being distributed with high weight and low volume. Pellets are cooked and formed in two extruders and forced through a die at temperatures below lOO C. The lower tanpera-ture prevents expansion and favors the production of a dense pellet. The basis for the wide variety of these products is their shape, which is imparted by the die design and configuration. 

FIGURE 11.9 Flowchart of the extrusion process to manufacture pellets further processed into gun-puffed cereals. 

Pellets are immediately dehydrated to lower their moisture content to about 10%-12%. The drying process is a critical step because water should be carefully removed from the pellet by evaporation. Optimally, drying should be performed in two sequential steps (predrying and drying). Control of moisture removal is achieved by adjusting the temperature-relative humidity residence time profile. Most plants 

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Imitation pork rinds, wheel shaped puffs or sticks obtained after frying of half-products or pellets. 

Most elaborate products, also called half-products or pellets generally produced by a two-step extrusion process (cooking and forming extruders). The formulation of these snacks uses a wide array of ingredients. These products require additional processes before they are ready for the consumer, such as baking and deep-fat frying. Most pellets are further processed by frying. 

Third-generation snacks Snack food category also known as half-products or pellets. This includes all intermediate or half-products made via thermoplastic extrusion that need further processing to reach consumers. The resulting pellets are usually fried or baked and flavored before packaging. 

Into a 5-liter autoclave, continuously stirred at a speed of 450 rpm, water, a dispersing agent, and polyethylene (powder or pellets) are introduced in the proportions set forth in Table II. After introduction of the initiator, the vinyl chloride is injected in such a quantity that, at the polymerization temperature, the vinyl chlorides partial pressure is lower than the vapor pressure of pure vinyl chloride at the same temperature. The vinyl chloride quantities compatible with this condition are easily determined by the absorption isotherms. When the pressure has dropped to at least half of its maximum value, the nontransformed vinyl chloride is removed. After filtering, washing, and drying, the product is collected. 

There are basically two families of snack items obtained with thermoplastic extruders the direct expanded snacks and the third-generation snacks produced from pellets or half-products obtained after the sequential cooking and forming extrusion steps. The direct extruded types are subdivided into baked puffs and fried puffs (Rooney and Sema-Saldivar 2003, Serna- Saldivar et al. 2008). 

The processing of the raw materials is different for plastic clays and lumpy shale. Plastic clays are crushed, ground, mixed, partially dehydrated and then formed into pellets of different sizes on a granulation table or similar apparatus before being thermally treated (half-wet process). Lumpy raw materials, such as shale, are only ground and, if necessary, classified (dry process) before thermal treatment. Adjustment of the bulk density of the final product to the required value is carried out during the subsequent thermal treatment. 

The smaller pellet is half the radius of the larger pellet, so the Thiele modulus is half as large or 0 = 0.964, which gives rj = 0.685. The production rate is therefore... 

Decoloration If the solution is colored and the recrystallized product is known or suspected to be colorless, treatment with decolorizing carbon (Sec. 2.18) is necessary. Caution Do nof add decolorizing carbon to a boiiing solution Cool the solution slightly, add half of a microspatula-tip full of powdered carbon or, preferably, a pellet or two of decolorizing carbon, and reheat to boiling for a few minutes. 

The majority of zeolite MR applications reported in the literature to date fall into the category of PBMRs. The reactor consists of a zeolite membrane with a conventional catalyst present in the form of a packed bed of pellets. The reaction takes place in the catalyst bed while the zeolite membrane serves mainly as a product separator (for H2 or H2O separation) [27] or a reactant distributor (for O2 distribution) [28]. Figure 3.5 illustrates a FAU-type zeolite PBMR combined with a packed bed reactor for dehydrogenation of cyclohexane [29]. Half of the catalyst is packed in the area upstream of the permeation portion to enhance the conversion, otherwise cyclohexane will preferentially permeate at the front end of the zeolite membrane, resulting in a decrease in conversion. 

The dried flower cones of the female hop plants of various sorts and cultivars are materials for alpha acids determinations. In the last decades, several preparations such as hop extracts, hop pellets, enriched hop, have been introduced on the market, aiming to stabilize the brewing value of hops or to improve the beer quality. Nowadays, more than half of the total hops production is processed in this way. 

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