Oxidative stability of polyunsaturated fatty acid-enriched infant flours based on teff and cowpea: Impact of natural antioxidants from amaranth leaves and black rice bran.

Abstract

From 4/6 months of age, complementary foods such as infant flours (IF) are introduced in the infant diet to supplement the nutritional intake of breast milk and/or infant formula that are no longer sufficient. However, the lipid profile and micronutrient content of IF are often unbalanced. In addition, the current lack of knowledge about oxidation mechanisms in low-moisture systems makes it difficult to control them in this type of food. The aim of this study was to better understand oxidation mechanisms in IF with optimized lipid profile for infant nutritional needs using climate smart crops, and with or without, the addition of vegetal sources of natural antioxidants. Five IF were formulated using climate smart crops, i.e. cowpea and teff flours, as sources of essential omega-3 fatty acids to complement soy flours. Four IF contained heat treated cowpea flour to evaluate the impact of lipoxygenases inactivation in this flour on global IF oxidative stability. Three IF were also fortified in long chain polyunsaturated fatty acid that are essential to support infant development to check whether this staple food could be good nutritional vector. Among these IF, two were enriched in natural antioxidant fractions with the addition of either powdered amaranth leaves or black rice bran, bringing carotenoids and phenolic compounds. The oxidative stability of IF was monitored over a 6-month storage period at 25 °C. The results showed that including teff and cowpea flours in the IF formulation enabled a balanced lipid profile (omega-6/omega-3 ratio close to 5) and ensured relatively good overall oxidative stability. However, 50 % of vitamin A was lost after 2 weeks of storage. Black rice bran and amaranth leaves acted as vitamin A stabilizers, delaying losses. This study unveiled that oxidation is triggered mainly during initial flour milling and propagated at a relatively slow rate over storage in these low moisture foods. Oxidation rate was related