EFFECT of EXTRUSION ON TRYPSIN INHIBITOR CONTENTS of SOY-SWEET POTATO MIXTURES

Effect of extrusion cooking on the chemical and nutritional properties of instant flours: a review

Satisfying the nutritional requirements of consumers has made food industries focus on the development of safe, innocuous, easy-to-prepare products with high nutritional quality through efficient processing technologies. Extrusion cooking has emerged as a prominent technology associated with the nutritional and functional attributes of food products. This review aims to establish a theoretical framework concerning the influence of extrusion parameters on the functional and nutritional properties of precooked or instant flours, both as end-products and ingredients. It highlights the pivotal role of process parameters within the extruder, including temperature, screw speed, and raw materials moisture content, among others, and elucidates their correlation with the modifications observed in the structural composition of these materials. Such modifications subsequently induce notable changes in the ultimate characteristics of the food product. Detailed insights into these transformations are provided within the subsequent sections, emphasizing their associations with critical phenomena such as nutrient availability, starch gelatinization, protein denaturation, enhanced in vitro digestibility, reduction in the content of antinutritional factors (ANFs), and the occurrence of Maillard reactions during specific processing stages. Drawing upon insights from available literature, it is concluded that these effects represent key attributes intertwined with the nutritional properties of the end-product during the production of instant flours.

Effect of processing and substitution levels of Ukwa (Treculia africana) on the anti-nutrient factors, in-vitro starch and protein digestibility and total essential amino-acid content of snack bars

Introduction

Ukwa (Treculia africana) is an indigenous edible seed. It is a strategic store of vital food nutrients that are available during a specific crucial time of the year when reliable sources of these nutrients are under cultivation and extremely scarce. In the past, only poor rural residents used to eat it, but today it is not only a specialty meal enjoyed by Nigeria's elite and metropolitan residents but also a source of foreign exchange.

Methods

In this study, Ukwa was processed into whole, dehulled, malted and defatted flours. Maize and coconut flours were blended with the respective Ukwa flours at the ratio of 0:95:5, 20:75:5, 25:70:5, 30:65:5, 35:60:5 and 95:0:5 for Ukwa flour:Maize flour:Coconut grits respectively for development of snack bars. A two-factor factorial experiment in a completely randomized block design was applied for the study of the effect of processing, substitution levels of Ukwa flour and the interaction of the two variables on the responses analyzed. Anti-nutrient content and proximate compositions of the flours were determined using standard procedures.

Results

Processing significantly reduced the anti-nutrient content and increased protein content of Ukwa flours. Up to 51.72% reduction of tannin was obtained by dehulling. Defatting, malting and dehulling resulted in 18.75, 34.37 and 65.62% reduction respectively in oxalate content. Highest reduction was obtained by dehulling, and was 70.69% in phytate, 79.95% in saponin, and 48.17% in trypsin inhibitor activity. Crude protein content of snack bars had 16.16 to 25.46% substitution main effect, and 19.43 to 22.65% processing main effect. In-vitro protein and starch digestibility increased with processing and decreased with increase in substituted level of Ukwa in the blend. Improvement, up to 9.97% by dehulling, 9.86% by malting and 8.64% by defatting, was recorded in in-vitro protein digestibility. An increase of 3.00 to 24.10% by defatting, 5.90 to 29.09% by malting and 9.70 to 31.80% by dehulling was recorded in in-vitro starch digestibility.

Discussion

Our study revealed that, all the processing methods adopted reduced the anti-nutrient content of ukwa flours. Protein content and total essential amino-acid (TEAA) showed significant increase with increased substituted level of ukwa flour. In-vitro protein and starch digestibility decreased with increase substituted level of ukwa flour. Snack bars formulated with 20% Ukwa showed the highest in-vitro starch and protein digestibility irrespective of the method of processing. Malted Ukwa based snack bars recorded the highest values of TEAA. Processing of this nutritious seeds and use of its flour to develop snack bars could enhance utilization and give convenience to consumers and encourage extensive farming of the crop.

Physicochemical and Rheological Properties of Optimised Cocoyam-Based Composite Flour Comprising Cassava Starch

Composite flour comprising cocoyam (Colocassia esculenta), bambara groundnut and cassava starch was produced. The proximate and minerals compositions and functional properties were optimized using optimal mixture design of response surface methodology. The antinutritional, pasting and farinograph analyses of the optimum blends were evaluated. Bambara groundnut improved protein, fibre, ash and minerals contents; cassava starch improved swelling capacity, least gelation and pasting characteristics. The optimum blends CBC1 (70% cocoyam flour, 18.33% bambara groundnut flour, 11.67% cassava starch) and CBC2 (69.17% cocoyam flour, 16.67% bambara groundnut flour, 14.17% cassava starch). were comparable to wheat–based flour samples (60% wheat, 30% cocoyam, 10% bambara groundnut flours) and (72% wheat, 19% cocoyam, 9% bambara groundnut flours) in terms of pasting and farinograph analyses.