The potential source for composite flours as food ingredient from local grown crops

N. Zainol,N.R.W. Kassim,A.S. Adnan,A.A.M. Zain,N.H. Zulkifli,A.A. Kamarudin,S. Subramanian

doi:10.26656/fr.2017.4(s2).s11

Abstract

The market of composite flour is growing as consumer nowadays choosing a healthy diet as personal preference. The suitability of the composite flour for use as intermediate or finish food ingredients highly depends on its physicochemical properties and its nutritional value. In this study, four types of local fruit crops (particularly their seeds) namely rambutan, cempedak, durian and nangka were dried and ground into powder form. The physicochemical properties such as bulk density, pH, water absorption capacity (WAC), oil absorption capacity (OAC), foam stability (FS), foam capacity (FC) as well as gelatinization properties of these composite flour were studied. Mineral content and heavy metal analytes were also determined. Results for bulk density from the least to the higher amount was 0.54±0.00 g/mL, 0.57±0.00 g/mL, 0.58±0.01 g/mL, 0.66±0.00 g/mL , 0.70±0.00 g/mL and 0.72±0.00 g/mL for rambutan flour, cempedak flour, tapioca flour, nangka flour, wheat flour and durian flour, respectively. Both cempedak flour and nangka flour showed the lowest pH value (5.72±0.01, 5.73±0.00), followed by rambutan flour and durian flour (6.67±0.00, 6.90±0.00) which similar to that tapioca flour and wheat flour (6.65±0.1, 6.08±0.0), respectively. Rambutan flour, cempedak flour and wheat flours showed the highest value in% of foam stability meanwhile these composite flours showed the lowest value in% of foam capacity. Results for water absorption capacity (WAC) and oil absorption capacity (OAC) in a range of 6% to 42% and 8% to 12% respectively, however, durian flour obtained the highest value for WAC while the value for OAC was the lowest. All of the composite flour possesses gelling properties at 13% concentration except for cempedak flour which completely gels at 20% of concentration. Rambutan flour showed the highest mineral analyte particularly in Zinc (107.19±0.17) and Copper (14.22±0.27) followed by nangka flour [Zinc (64.20±0.32) and Copper (10.40±0.12)] and durian flour [Zinc (52.38±0.42) and Copper (7.97±0.05)]. Level of heavy metal toxicity was under risk for all types of composite flour.

Highlights

Composite flours are a mixture of different vegetable flours rich in starch or protein, with or without wheat flour, for certain group of bakery products and its definition by Anon et al (2018) is “composite flours are a mixture of flours from tubers rich in starch and/or cereals, with or without wheat flour”
High bulk density of flour suggests the suitability for use in food preparations especially as a thickener in food products since it helps to reduce paste thickness which is an important factor in convalescent and child feeding (Chandra et al, 2015)
Increase in water absorption capacity (WAC) is related to the fibre content due to increasing hydroxyl groups allowing more water interaction via hydrogen bonding (Chareonthaikij et al, 2016). These results suggest lower WAC may be useful for food formulations such as partial wheat flour replacer for dough handling in baking and pastry products (Chen, 2016)

Summary

Introduction

Composite flours are a mixture of different vegetable flours rich in starch or protein, with or without wheat flour, for certain group of bakery products and its definition by Anon et al (2018) is “composite flours are a mixture of flours from tubers rich in starch (e.g. cassava, yam, sweet potato) and/or cereals (e.g. maize, rice, millet, buckwheat), with or without wheat flour”. Wheat flour is commonly used as it contains gluten which is responsible for the elasticity of the dough, improving the texture of the baked products. Gluten contains 75-86% protein and the remaining nutrients are carbohydrate and lipid, held strongly within the glutenprotein matrix (Anon et al, 2018). There have been several studies conducted on fruits which have been combined with wheat flour to produce bakery products. A study done by Feili et al (2014) reported that 5% substitution of the jackfruit rind flour gave the highest mark for overall acceptance compared to 10% and 15% substitution of jackfruit rind flour with wheat flour.

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Conclusion