Stability foodstuffs

Since several previous reviews have treated betalain stability, the interested reader is referred to those for more detailed information. "" " " This chapter is intended to present some general aspects of handling betalainic foodstuffs. 

P.B.24 x, a greenish blue compound, is registered in the USA as FD C Blue 1 for use in foodstuffs, pharmaceuticals, and cosmetics, provided certain purity standards are met. The pigment possesses poor lightfastness. It largely parallels P.B.24 , also in terms of tinctorial strength and stability to organic solvents. 

Stabilizers Substance which makes it possible to maintain the physicochemical state of a foodstuff stabilizers include substances which enable maintenance of a homogenous dispersion of two or more immiscible substances in a foodstuff and include also substances which stabilize, retain or intensity an existing colour of a foodstuff... 

Uses. As an antioxidant in the rubber and plastics industry as a stabilizer in polyethylene and polyolefin packaging materials for foodstuffs... 

Instead, foodstuffs are a greater challenge due to the complexity of their matrices and the low natural concentration of vitamins in food. The different stability and the numerous vitamers present in foodstuffs required dedicated extraction procedures. The simultaneous extraction of vitamin B B2 has been performed in a unique step several times. However their detection, if MS is not applied, usually needs to be performed under different conditions, which means carrying out two different chromatographic analyses. 

The methods for testing the oxidative stability of fats and oils in foodstuffs and the assessment of the oxidation state of oils and fats" have been reviewed. A critical review appeared on the FIA methods for edible oils, including various acidity indices . ... 

The stability of the flavour in the food is an enormously complex issue. In order to come to a reliable prediction, the reactivity of flavour compounds and the embedding in the corresponding food matrix have to be considered. The interactions of flavours and foodstuff can be clustered into two main groups ... 

While in ancient times, the sensorial properties of a flavour for foodstuffs were of major importance, modern flavours have to perform like multifunctional systems. Physical form, chemical and mechanical stability and controlled release mechanisms are meanwhile essential criteria for the flavour quality. All these properties have to be addressed by a flavourist in close cooperation with technologists. Therefore, knowledge about food product properties must lead to a careful and intelligent evaluation of the flavour system as an important driver for the success of the final product. 

The term food colloids can be applied to all edible multi-phase systems such as foams, gels, dispersions and emulsions. Therefore, most manufactured foodstuffs can be classified as food colloids, and some natural ones also (notably milk). One of the key features of such systems is that they require the addition of a combination of surface-active molecules and thickeners for control of their texture and shelf-life. To achieve the requirements of consumers and food technologists, various combinations of proteins and polysaccharides are routinely used. The structures formed by these biopolymers in the bulk aqueous phase and at the surface of droplets and bubbles determine the long-term stability and rheological properties of food colloids. These structures are determined by the nature of the various kinds of biopolymer-biopolymer interactions, as well as by the interactions of the biopolymers with other food ingredients such as low-molecular-weight surfactants (emulsifiers). 

Liquid foodstuffs, for example milk products must be submitted to homogenisation treatment in order to improve their long-term physical stability ("shelf life"). The liquid is pumped at very high pressure by a multiplex reciprocating piston pump through the narrow clearances of a hydraulically controlled homogenisation valve (Fig. 1.4-4, C, bottom). 

Ultra-high-temperature treatment (UHT) is now the most widely exploited method in the food industry to stabilize microbiologically any foodstuff. It consists of heating at an ultra high-temperature for a short period of time for example, a treatment at 145°C for 2 seconds is sufficient to assure a total microbial- and spore inactivation. The microbial death is principally due to irreversible cell damage (e.g., of proteins, DNA, RNA, vitamins) enzymes are inactivated by heat which modifies their active sites. 

Lipids are important macromolecules in food. A food product s nutritional value as well as its flavor, texture, general palatability, and storage stability are affected by lipids. Therefore, both physical and chemical criteria are needed by the food processor to assess or monitor the quality of fats and oils. The basic characteristics of certain food items, such as edible oils, will be dependent upon their source. Variation from these norms can be ascertained before the oils are used in other foodstuffs. In effect, knowledge of the quality of the lipid before shipping the product to market, or use in fabricated foods, is of economic importance to the processor. 

The time to reach a certain PV may be used as an index of oxidative stability for food lipids. The effects of antioxidants and food processing on fats are often monitored in this way. Thus, a longer time period to reach a certain PV is generally indicative of a better antioxidant activity for the additive under examination. However, a low PV represents either early or advanced oxidation the breakdown of peroxides to secondary oxidation products will result in a decrease in PVs during the storage period. For determination in foodstuff, a major disadvantage to the classical iodometric PV assay is that a 5-g test portion is required it is sometimes difficult to obtain sufficient quantities of lipid from foods low in fat. Despite its drawbacks, PV determination is one of the most common tests employed to monitor lipid oxidation. 

The OSI was primarily developed for oil or fat samples. It is possible to use the method on lipids extracted from foodstuffs however, such lipids may not have the same oxidative stability as the food since the physical structures are different. Additionally, muscle foods oxidize rapidly at elevated temperature due to physical and chemical alterations during cooking thus, this method probably will not be useful with raw meats. 

In foods, the simultaneous HPLC analysis of several vitamins is feasible only under special conditions, for example, determination of fortified, free vitamins rather than endogenous ones, which are often bound to other food components, or determination of vitamins in relatively simple foodstuffs, such as fruit juice. The HPLC separation per se of multiple vitamins is not difficult it is their simultaneous, nondegradative extraction from foods that is problematic. Developing a single set of extraction conditions that satisfies the diverse physicochemical properties and stability requirements of several vitamins is a challenge. 

In order to extract the maximal energy out of the available foodstuff oxidative phosphorylation should operate at the state of optimal efficiency in vivo. Since a zero as well as an infinite load conductance both lead to a zero efficiency state, obviously there must be a finite value of the load conductance permitting the operation of the energy converter at optimal efficiency. For linear thermodynamic systems like the one given in equations (1) and (2) the theorem of minimal entropy production at steady state constitutes a general evolution criterion as well as a stability criterion.3 Therefore, the value of the load conductance permitting optimal efficiency of oxidative phosphorylation can be calculated by minimizing the entropy production of the system (oxidative phosphorylation with an attached load)... 

Some other practical situations where particle aggregation is important include the precipitation of colloidal mud at the mouth of a river due to the salinity of the sea-water exceeding the critical coagulation concentration, land (e.g. mountainside) stability, building and road foundations, the retention of a porous structure in filtration, mineral processing117 and paper making. Control of particle aggregation is also of primary importance in adhesives, inks, pharmaceuticals, cosmetics, foodstuffs and lubricants. 

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