Textural modification

A good compilation of the functions of fats in various food products is available (26). Some functions are quite subtle, eg, fats lend sheen, color, color development, and crystallinity. One of the principal roles is that of texture modification which includes viscosity, tenderness (shortening), control of ice crystals, elasticity, and flakiness, as in puff pastry. Fats also contribute to moisture retention, flavor in cultured dairy products, and heat transfer in deep fried foods. For the new technology of microwave cooking, fats assist in the distribution of the heating patterns of microwave cooking. 

FIG. 15 Texture modification (percentage of raw fruit texture) and protopectin content (mg/100 g wet weight) before (BF) and after (AF) freezing of strawberry slices not pretreated (NT) or air dried at 80 °C up to 60% weight reduction without (AD) or following 60-min osmotic dehydration (OAD) in 60% (w/w) sucrose solution at 25 °C at atmospheric pressure (Brimar, 2002). 

FACT is limited to treating biodegradable contaminants. It cannot treat metals, inorganic contaminants, or halogenated compounds. For sludge-type soils that are heavily contaminated with tar, some texture modification may be required prior to treatment. 

Nutrient availability Texture modification Pulp removal... 

Porous texture modifications of a series of silica and silica-alumina hydrogels and xerogels a thermoporometry study. 

In thermoporometry experiments the pore radius is deduced from the measurement of the solidification temperature and the volume of these pores is calculated from the energy involved during the phase transition. The pore radius distribution and the pore surface are then calculated. The pore texture can be described from numerical values (mean pore radius, total pore volume or surface, etc...) or by curves. For example, curves of figure 1 are the cumulative pore volume vs pore radius while curves of figure 2 are the pore radius distributions. Texture modifications are conveniently depicted by the pore size distribution curves. 

It is noteworthy that ageing has the same effect on the two kinds of gel (stirred or non stirred) increasing of pore volume, surface and mean diameter, and broadening of the pore range. As a consequence, to avoid these undesirable texture modifications, thermoporometry measurements must be carried out as soon as possible after the preparation of hydrogel samples (within 24 hours). 

Another interesting fact appears in table 3 textural modifications induced in silica hydrogel texture still exist in silica-alumina hydrogels. 

The silica hydrogel is a compliant material whose network building-up is not completed when alumina is added. So, alumina precipitation can easily modify the silica gel structure and induce drastic texture modifications. 

Texture modifications occur mainly during the first step of drying (the constant rate period) and are related to the visco-elastic properties of the gel network [6]. During the second step of drying (the falling rate period), liquid water leaves the capillaries and the pore walls can be damaged by forces linked to the existence of liquid-gas meniscus [6, 7],... 

The drying mode and drying operating parameters must be carefully chosen to minimize the gel texture modifications. 

Tomato fruit appeared to represent a unique system for investigating possible variability in the functions of pectins in texture modifications. Firstly, the tomato fruit is composed of distinct tissue types, including locular gel and pericarp which exhibit markedly different patterns of tissue autolysis. Locular gel develops prior to ripening of pericarp and eventually, toward the terminal stage of ripening, exhibits an almost liquid nature. This developmental scenario is in some respects similar to the ethylene-induced maceration of watermelon fruit (27), a process involving greatly increased levels of EDG and extensive solubilization and depolymerization of pectins (23). In contrast, tomato locular gel has been reported to contain little ( ) or no EDG activity (28). The objective of this study was to examine some of the structural features of pectins from tomato pericarp and gel, and to relate this information to the textural characteristics of these tissues. 

Uses Film-former for pharmaceuticals, esp. aq. film coatings, barriers, texture modification, binding, adhesives filler, humectant for pharmaceutical cleansers film-former, encapsulation aid for spray drying Features Low hygroscopicity nonirritating low vise. 

Autoclaving is performed in a batch reactor under high pressure and different temperatures. There are thermal and hydrothermal transformations in the presence of steam water, resulting in structural changes. In the presence of a solvent, the precipitated solid suffers structural and textural modifications, but in principle the main steps are ... 

Fruits ripen in two major ways climacteric and non-climacteric. The former type involves both autocatalytic evolution of ethylene and a rise in respiration whereas the latter shows no increase in ethylene formation and downward drifts in respiration [14]. In both types, fruit ripening is characterized by many biochemical and physiological changes such as chlorophyll d radation, pigment accumulation, textural modification and the production of volatile aromatic compounds. 

Maury S, Buisson P, Pierre AC (2001) Potous Texture Modification of Silica Aerogels in Liquid Media and Its Effect on the Activity of a Lipase. Langmuir 17 6443-6446... 

Whatever the catalyst precursor, the intrusion volume is 40 to 50% that of the pure support indicating that mercury porosimetry also detects some texture modifications in the catalyst, as compared to the original carrier. However, if we take into account that 60% of the mass in the calcined catalyst is due to nickel, we reach the conclusion that the total pore volume of the carrier in the supported precursor is not different from that in the pure carrier. 

J. Jaramillo, P.M. Alvarez, V. Gomez-Serrano, Oxidation of activated carbon by dry and wet methods surface chemistry and textural modifications. Fuel. Process. Technol. 91 (2000) 1768-1775. 

Hence pronounced textural modifications happen. This is the first serious drawback that we must avoid to preserve the expanded texture of the sohd network. 

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