Lipid energy content

The increase in energy content of an atom, ion, or molecular entity or the process that makes an atom, ion, or molecular entity more active or reactive. In enzymology, activation often refers to processes that result in increased enzyme activity. For example, increasing temperature often can have a positive effect on enzyme activity (See Arrhenius Equation). Other examples of enzyme activation include (1) proteolysis of zymogens (2) alterations in ionic strength (3) alterations due to pH changes (4) activation in cooperative systems (5) lipid or membrane interface activation (6) metal ion effects (7) autocatalysis and (8) covalent modification. 

J to their molecular components. Then one of two things happens either your body burns these molecular components for their energy content through a process known as cellular respiration, or these components are used as the building blocks for your body s own versions of carbohydrates, lipids, proteins, and nucleic acids. The sum total of all these biochemical activities is what we call metabolism. Two forms of metabolism are catabolism and anabolism, and Figure 13.41 shows the major catabolic and anabolic pathways of living organisms. 

Dawson, A.S. and Grimm, A.S. (1980). Quantitative seasonal changes in the protein, lipid and energy content of the carcass, ovaries and liver of adult female plaice. Journal of Experimental Biology 76,493-504. 

As a result of widespread concern about weight control, the production of lipid materials with reduced or zero calories has been of special interest recently. The lipid-based fat replacers are esters that resist enzymatic hydrolysis, are poorly absorbed, have relatively low-energy content, or have different modes of metabolism. Many of these materials can be made from soybean oil or contain soybean oil fatty acids. Sucrose polyester or other synthetic esters and diacylglycerol oils are examples of these low-calorie fat substimtes (268-274). 

The U. S. Department of Agriculture maintains the USDA National Nutrient Database for Standard Reference, which contains over 7000 food items with data on the energy content, minerals, vitamins, and other properties of nutritional interest. The table here includes about 600 common foods extracted from that database. The properties listed are the energy content (in effect, the enthalpy of combustion) the content of carbohydrates, proteins, and lipids (fats) the cholesterol content and the amount of sodium, potassium, calcium, magnesium, iron, copper, zinc, manganese, phosphorus, and selenium. AU values are given for a 100 gram sample of the food. 

Dietary fat supplements are freqnently nsed to increase the energy content in the hens ration. Increased dietary fat does not lead to an increase in the fat content in the egg yolk, but the EA and TAG spectra in egg yolk lipids do change in relation to the fat composition of the feed. There is nearly always a connection between diet and the egg yoUc FA spectrnm, bnt the amonnts of FA do not completely correspond. 

Oleic acid (OA) is a monounsaturated fatty acid with a number of potential health effects (Sales-Campos, de Souza, Peghini, da Silva, and Cardoso, 2013) and can therefore be a constituent of composite functional foods when it substitutes saturated fats. In addition, foods naturally high in oleic acid, e.g. olive oil, can be considered as functional food. However, the high energy content of all oils represents the main limitation on recommendations to increase the consumption of any particular oil. The overconsumption of oleic acid should not be recommended but to substitute other lipids with oleic acid, always aiming to strike a balance between energy intake and expenditure, preferably at a higher rather than a lower level (Trichopoulou and Dilis, 2007). 

On the basis of a well-established consensus that replacing saturated fats in the diet with oleic acid contributes to the maintenance of normal blood cholesterol levels, functional foods high in oleic acid can be promoted by related health claims in the EU. However, due to its high-energy content it is not recommended to increase the consumption of any particular fat, but to substitute other lipids with oleic acid. 

Oleic acid is a monounsaturated fatty acid and natural constituent of a number of foods, partieularly vegetable oils. On the basis of proven beneficial health effects it is also a possible ingredient in processed functional foods. However, due to its high energy content it is not recommended to increase the consumption of any particular fat, but to substitute other lipids with oleic acid. While there is a well-established consensus that replacing saturated fats in the diet with oleic acid or other unsaturated fats contributes to the maintenance of normal blood cholesterol levels, a series of other effects has also been studied, including the modulation of inflammatory markers, blood pressure, insulin sensitivity, gastrointestinal fimctions and even various cancers. This book discusses oleic acid s health effects, as well as its production, and how it is used. 

Fecal energy— This fraction represents the energy content of the food constituents that are not asorbed in the digestive tract. The most common contributor to fecal energy in the human diet is cellulose and the related carbohydrates that collectively constitute the crude fiber of plant foods. Certain lipids and nitrogenous substances also contribute to the fecal energy. 

At the end of this section an essential caveat should be kept in mind. Caloric values less than 17.6 kJ/g afdw should be considered with suspicion. Carbohydrates bum with the lowest energy content of 17.6 kJ/g, proteins and lipids with higher values (see Table 1). Combustion heats lower than 17.6 kJ/g afdw may be due to a wrong determination of the ash fraction or to contributions of inorganic reactions during burning (see e.g. [37]). 

---