Foodstuffs drying

Flumectant Substance which prevents foodstuffs drying out by counteracting the effect of an atmosphere having a low degree of humidity, or promote the dissolution of a powder in an aqueous medium... 

Sublimation temperatures are in the range of —10 to —40°C and corresponding vapor pressures of water are 2.6-0.13 mbar. Cabinet tray dryers are the most commonly used type. The trays are lifted out of contact with hot surfaces so the heat transfer is entirely by radiation. Loading of 2.5 lb/sqft is usual for foodstuffs. Drying capacity of shelf-type freeze dryers is 0.1-1.0kg/(hr)(m2 exposed surface). Another estimate is 0.5-1.61b/(hr)(sqft). The ice surface has been found to recede at the rate of 1 mm/hr. Freeze drying also is carried out to a limited extent in vacuum pans, vibrating conveyors, and fluidized beds. Condensers operate as low as —70°C. 

Zogzas, N., Marouhs, Z.B., and Marinos-Kouris, D., Moisture diffiisivity data compilation in foodstuffs. Drying TechnoL, 14 2225-2253,1996. 

HCOOCHjCHj. Colourless liquid with the odour of peach-kernels b.p. 54 C, Prepared by boiling ethanol and methanoic acid in the presence of a little sulphuric acid the product is diluted with water and the insoluble ester separated and distilled. Used as a fumigant and larvicide for dried fruits, tobacco and foodstuffs. It is also used in the synthesis of aldehydes. 

Dry Ice. Refrigeration of foodstuffs, especially ice cream, meat products, and frozen foods, is the principal use for soHd carbon dioxide. Dry ice is especially useful for chilling ice cream products because it can be easily sawed into thin slabs and leaves no Hquid residue upon evaporation. Cmshed dry ice may be mixed directly with other products without contaminating them and is widely used in the processing of substances that must be kept cold. Dry ice is mixed with molded substances that must be kept cold. For example, dry ice is mixed with molded mbber articles in a tumbling dmm to chill them sufficiently so that the thin flash or rind becomes brittle and breaks off. It is also used to chill golf-ball centers before winding. 

Many foodstuffs are in the form of solids or processed powders, and do not offer serious corrosion problems, though mild steel equipment in infrequent use, or after washing down, can develop slightly rusted surfaces. This material is usually undesirable if it finds its way into food products. Scouring batches of dry foodstuffs is one solution to the problem if stainless steel is not used or affordable. Hygiene and cleanliness are, however, dominant factors. 

Organic chemicals Most organic liquids, other than the stronger acids, only attack zinc slowly. Zinc is, therefore, suitable for storage tanks for liquid hydrocarbons such as motor fuels, for phenols and for trichlorethy-lene degreasers. Zinc or zinc-coated vessels are not recommended for use in contact with acid foodstuffs, but are regularly used for dry foods. Zinc in small quantities is beneficial in the human diet. 

Cans with replaceable closures for such products as dry foodstuffs, pharmaceuticals, tobacco, solvents, liquid fuels and paint. These usually contain an appreciable amount of oxygen. Tinplate closures for bottles and jars made of non-metallic materials may also be considered in this category. 

This red color has not yet been approved for uses in foods or cosmetics. However, studies on rats fed with the dried biomass have not revealed any adverse growth or histological effects. Future efforts should thus be devoted toward obtaining official approval of use of the color in foodstuffs for human consumption. 

Lobbying by other P-carotene producers — In addition to approvals of mixed carotenes from palm oil, P-carotene from Dunaliella microalgae, and other natural products, the EU Health and Consumer Protection Directorate General was asked for an opinion on the safety of P-carotene from a dried biomass source, obtained from a fermentation process with Blakeslea trispora for use as a coloring matter for foodstuffs. 

The addition of water or the use of an aqueous solvent mixture is important for the extraction of other organic analytes from dry foodstuffs or dehydrated foods. It is particularly necessary in aiding the permeation of solvent through freeze-dried samples. 

Dry-ashing Ignition of organic matter in a furnace. Resulting ash dissolved in acid for further analysis Metals in organic solid samples (e.g. metals in foodstuffs)... 

Basically the chamber plants described in Section 2.4 can be used for foodstuffs and other products, as described in Sections 5.1 and 5.2. Freeze drying plants for food and similar products have to handle large quantities of product. The cleaning requirements remain, but no sterilization is necessary. The product can be transported in trays as described in Section 2.2.2 and dried in cylindrical tunnels. Figure 2.52 shows the two systems most commonly used to day. Their characteristic features are ... 

Table 5. Content of copper in foodstuffs from Baimak Cu-Zn bio geochemical provinces of South Ural sub-region of biosphere, ppm by dry weight.

Food (cereal and other foodstuffs) Extraction of sample with water/ acetonitrile, dried GC/ECD at low detection voltage (free cyanide) 0.1 ppm 90 Heuser and Scud more 1969... 

Foodstuffs subject to drying by combustion gases (containing oxides of nitrogen) such as malt for production of beer and whiskey, low-fat dried milk products and spices. 

Widening interest in the quaHty of the environment has led to increased demand for information on a wide range of trace-metal contents of foodstuffs. Trace metals in foodstuffs are normally determined by spectroscopic techniques after complete destruction of the organic matrix. Destruction is achieved either by wet oxidation or by dry ashing additional treatment is normally required in order to obtain the metals of interest in a form suitable for analysis. Both methods of destruction are time consuming and tedious this is particularly true of the wet-oxidation procedure, which has the additional disadvantage of being potentially hazardous the methods require considerable analytical skill and experience. Both methods are prone to produce erroneous results either by the loss of an element of interest or by adventitious contamination from the component parts... 

The performance of the system was clearly demonstrated for a wide range of foodstuffs. The data for the NBS (National Bureau of Standards) bovine hver (Table 4.1) shows that the automatic system is capable of giving accurate results. Samples were freeze-dried on receipt. Measurements on manually digested samples were made by atomic-absorption spectrophotometry, and by plasma-emission spectrometry on automatically digested... 

The slow spontaneous oxidation of compounds in the presence of oxygen is termed autoxidation (autooxidation). This radical process is responsible for a variety of transformations, such as the drying of paints and varnishes, the development of rancidity in foodstuff fats and oils, the perishing of rabber, air oxidation of aldehydes to acids, and the formation of peroxides in ethers. 

A varied diet containing a wide range of foodstuffs provides adequate intake of vitamins for most people, and supplementing these amounts will have no beneficial effect and may result in the toxicity associated with hypervitaminosis. The DRI also includes the tolerable... 

Endemic crippling skeletal fluorosis is confined in temperate climates to individuals exposed continuously over many years to very high levels of fluoride these cases are associated with industrial situations, with unusually high levels of fluoride in drinking water (e.g., 10 mg/L) or the use of high fluoride coal for cooking and drying foodstuffs indoors [6,17,55]. 

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