Scientists

Technical Aspects

Fat highly contributes in the texture, aroma, and mouth-feel perception of food products. It constitutes a solvent and a vector for aroma compounds and controls their retention and release. Salt and sugar act on the ratio of aroma compounds present in the gas phase. Salt and sugar act on the ratio of aroma compounds present in the gas phase (Voilley et al., 2006).

Concerning flavour release and perception, fat interacts with sweetness and saltiness. For example, fat has been found to mask saltiness in many food systems. For some concentration levels, it also acts on sodium release in mouth. Moreover, today, fat perception is hypothesized to be a single stimulus, with its specific sensory receptors (Besnard, Gaillard, Passilly-Degrace, Martin & Chevrot, 2010).

Consequently, we can also think that perceptive interactions can exist between fat perception and taste or aroma perception, increasing or decreasing these ones. Concerning sugar/salt, sweet perception generally masks saltiness intensity. Fat, salt and sugar participate to the food structure and consequently to its mechanical properties. Current reduction strategies are mainly based on substituting these ingredients:

Salt

Several salt substitutes have been developed but they present several drawbacks. The most used is the potassium chloride for a partial or total substitution of sodium chloride. However, when the ration is over 50% KCl, bitterness appears with off-flavour such as metallic note and KCl presents health risk for populations with diabetes, renal or cardiac pathologies. Additional salts or organic compounds were also used to mask KCl off-flavours. In this way, co-crystallisation of KCl and Ribotide (commercial mixture of nucleotides) was proposed. Yeast and marine algae extracts, lactates, nucleotides were used as saltiness enhancers. Monosodium glutamate, responsible for umami taste, is also a saltiness enhancer but it contains sodium ions and is also suspected to be responsible for neurotoxicity if consumed in excess. Another potential strategy is on optimizing the form of salt (areamorphology of the crystal) which can be dendritic, granular or fleecy in order to increase the salt bioavailability in mouth by a quicker dissolution. Also, salt can be used for its antimicrobial properties and play a key role in the shelf life of food products. Its reduction or substitution can directly impact on microbial quality and indirectly on other quality characteristics (nutritional, sensorial, organoleptic qualities).

Fat

Fat substitution is possible with synthetic substances with physico-chemical characteristics close to natural triglycerides but with a lower energetic power and often a lower digestibility. They are compatible with natural fat and can replace them at least partially on a technological viewpoint. Some of them have a high thermal stability and can be used for frying food process such as sorbitol, sugar polyesters and polyglycerol. Generally, triglycerides with shorter chain fatty acids have a lower energetic power than natural triglycerides. However, some of these fat substitutes can modify the bioavailability of macro- and micronutrients, be responsible for digestive troubles and lower vitamins absorption. Another way to decrease fat content in food is to replace a part of fat in lipid /water emulsion by small water droplets. This leads to a multiple water/oil/water emulsion but their stability is lower and needs the addition of emulsifiers, thickeners and stabilisers to get product formulations with a lower fat content and acceptable sensory properties. The nature of the fat is also important, as the proportion of saturated fats in our diet should be reduced to less that 10% of our energy intake. This can be straightforward with some foods and processes through replacing heavily saturated animal fats with liquid vegetable based oils. For meat products, some producers are adding polyunsaturated fats and omega 3 and 6 to animal feed as they are then transferred to the animal tissue, to reduce saturated fat levels. However, from a technological point of view, some foods (eg bread, bakery and dairy products) rely on solid (saturated) fats to provide specific structural and textural properties which are not possible using liquid oils which are high in unsaturated fatty acids.

Sugar

Simple sugars such as fructose or sucrose are responsible for the unanimously appreciated sweet taste. Their role in food texture is important as they provide body and volume. They are important major constituent in cake making and important binders for dough. Their presence improves the manipulation of the dough with industrial machines, convey sweetness and decreases the water activity of the final product, improving the shelf-life. In order to reduce caloric intake, they can be replaced by intensive sweeteners (aspartame, sucralose, stevia, etc ...), this way keeping the same sweetness profile without the added calories. However because of their strong nature, small volumes are required to achieve the same sweetness level, resulting in losses of volume (as bulking agents) and modifications in texture, furthermore depending on the country some are not authorized to be added to specific foods. Alternatively, a part of simple sugars can be replaced by soluble fibres or other carbohydrates which can add volume to the food such as polyols and fructo-oligosaccharides. However, the use of polyols is limited due to their postingestive effects as laxatives, and therefore it is important to combine them with other alternatives to achieve the target taste and texture.

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