Plant food dispersions properties

Because of the compressible nature of food dispersions, the direct determination of the magnitude of centrifugal force employed in the separation of the phases. Therefore, rheological properties of plant food dispersions, such tomato concentrates and concentrated orange juice, are based on the mass of pulp. In starch dispersions, they are based on the mass fraction of starch granules, denoted as cQ, as described in Chapter 4. 

Plant food dispersions such as tomato concentrates and concentrated orange juice are important items of commerce. The viscosity function and the yield stress are two important rheological properties that have received considerable attention. Corrections for slip, due to the formation of a thin layer of fluid next to solid surfaces, in a concentric cylinder viscometer depended on the magnitudes of applied torque and on the shear-thinning characteristics of the dispersion. Mixer viscometers were used for obtaining shear rate-shear stress and yield stress data, but the latter were higher in magnitude than those obtained by extrapolation of flow data. 

For practical reasons in a food plant where advanced instrumentation is not always available, it is desirable to have recourse to simple techniques to assess quality. Any property of a polysaccharide dispersion can do this if quality factors are adequately referenced. 

Prominent markets today for fine CaCOs are as fillers in paper, paint, PVC, rubber, putty, cosmetics, and toothpaste and as an antacid and a calcium supplement in foods. Surface-coated grades are also produced and are more easily dispersed in organic materials. CaCOs is also used to coat paper, and its use as a filler has increased rapidly with the increase in alkaline papermaking. Many small precipitation plants now operate at papermill sites. Controlled precipitation of calcium carbonate allows control of crystal geometry and particle size distribution. This allows custom production with attractive properties for various markets. With the recent expansion in precipitated calcium carbonate capacity, there are fewer possibilities for disposal of the relatively low-quality material from a brine plant. 

The seed is dispersed from the mother plant endowed with a store of food reserves of protein, carbohydrate and fat in a more concentrated package than occurs anywhere else on the plant. Animals exploit this property when using seeds as an extremely important part of their diet. It is also debatable that civilization began its development when man started to cultivate plants for the food that their seeds provided, especially the cereals—wheat and barley in the Near East and Europe, rice in Asia and maize in the Americas. It need hardly be necessary to remind the reader, moreover, that virtually all of man s exploitation of plants in agriculture depends upon seeds —that they can be stored, transported, multiplied and, most important of all, germinated ... 

Irrespective of the actual mechanisms behind the reduction of cholesterol absorption by plant sterols, solubilization into the emulsified fat phase of the food digest is a prerequisite for plant sterols to be incorporated into the micelles. The physical properties of free, crystalline plant sterols and stanols limit their applicability in foods and their cholesterol-lowering effect in many food matrices, but these limitations can be partly solved by producing fat dispersions of plant sterols or emulsifier-sterol aggregates. Currently, however, plant sterols are mainly used as fatty acid esters in functional foods. 

Hydrocolloids are high-molecular-weight hydrophihc biopolymers used as functional ingredients in the food industry for the control of viscosity, gelation, microstructure, texture, flavor, and shelf-hfe. The term hydrocolloid encompasses all the polysaccharides that are extracted from plants, seaweeds, and microbial sources, as well as gums derived from plant exudates, and modified biopolymers made by chemical or enzymatic treatment to be soluble or dispersible in water. The general molecular and functional properties of proteins and polysaccharides are compared in Table 5.1. 

Uses Emulsifier food emulsifier dispersant Features Highly hydrophilic plant-derived Properties Lt. yel. solid water-sol. HLB 15 Decaglyn 1-L [Nikko Chems. Co. Ltd]... 

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