Nutritional aspects of food extrusion: a review

Abstract

Extrusion cooking, as a multi-step, multi-functional and thermal/mechanical process, has permitted a large number of food applications. Effects of extrusion cooking on nutritional quality are ambiguous. Beneficial effects include destruction of antinutritional factors, gelatinisation of starch, increased soluble dietary fibre and reduction of lipid oxidation. On the other hand, Maillard reactions between protein and sugars reduce the nutritional value of the protein, depending on the raw material types, their composition and process conditions. Heat-labile vitamins may be lost to varying extents. Changes in proteins and amino acid profile, carbohydrates, dietary fibre, vitamins, mineral content and some non-nutrient healthful components of food may be either beneficial or deleterious. The present paper reviews the mechanisms underlying these changes, as well as the influence of process variables and feed characteristics. Mild extrusion conditions (high moisture content, low residence time, low temperature) improve the nutritional quality, while high extrusion temperatures (P200°C), low moisture contents (<15%) and/or improper formulation (e.g. presence of high-reactive sugars) can impair nutritional quality adversely. To obtain a nutritionally balanced extruded product, careful control of process parameters is essential.

Cassava and turmeric flour blends as new raw materials to extruded snacks

“…Foods with lower moisture tend to be more viscous than those with higher moisture and, therefore, the pressure differential would be smaller for higher moisture foods, leading to a less expanded product (Singh, Gamilath;Wakeling, 2007).…”

Development of radish fibre based snack by response surface methodology (RSM)

“…DF also acts as a bulking agent, normalizing intestinal mortality and preventing diverticular disease. Some times it may also be important in reducing colonic cancer and in preventing hyperglycemia in diabetic patients (Larrea et al 2005a, b;Singh et al 2007). In recent years, diverse products with high fibre content have been developed.…”

Extruded corn gruels containing linden flowers: quantitation of phenolic compounds and selected quality characteristics

“…The process changes texture, gelatinizes starch, cross-links proteins, and creates flavors [4]. It may inactivate antinutritional factors, denature undesirable enzymes or reduce lipid oxidation [5].…”

“…and biologically important monomers and dimers from polymer chains [16]. Extruded product enrichment with bioactive compounds is limited by secondary plant metabolites' low thermal stability and their susceptibility to changes during processing [5,17].…”