CHANGES IN PHYSICOCHEMICAL PROPERTIES OF INSTANT KUNUN ZAKI FLOURS PRODUCED FROM MILLET (PENNISETUM TYPHOIDUEM) AND MALTS OF COWPEA (VIGNA UNGUICULATA) AND SOYBEAN (GLYCINE MAX) DURING STORAGE.

ABSTRACT

In this study, instant kunun zaki powders were produced from millet-cowpea malt and millet- soybean malt. The instant powders were packaged in polypropylene plastics and stored for 3 months. During this period, studies of the changes in physiochemical and functional properties of the packaged flour were carried out every 30 days for 3 months. Production of instant powders was by blending millet with malt of cowpea for millet cowpea malt (MC_m) and millet with malt of soybean for millet-soybean malt (MS_m) each in the ratio of 70:30 w/w. Ginger was added to each blend in the ratio 15:1 w/w. The blends were incubated at 28+3⁰C for 15 minutes and instantized by steam-heating for 10 minutes followed by oven drying at 50⁰C to a moisture content of 6.23% for MC_m and 6.34% for MS_m. The flour blends were then packaged in polypropylene plastic (12x18cm) and stored for three months at 28+3⁰C. During this storage period, studies of the changes in physiochemical properties of the packaged flour were determined every 30 days. The results showed that diastatic activities of cowpea and soybean increased with malting, with that of cowpea being higher (63.33⁰L) than that of soybean (30.00⁰L). Protein and sugar contents increased after malting, whereas fat and TBA content decreased with malting. During storage however, there was a general increase in moisture content, sugar, fat, TBA, tannin and trypsin inhibitor in all the samples. Protein content decreased with storage. Water absorption capacity, bulk density, solubility, dispersibility and viscosity decreased with storage time. The particle sizes of the flours increased with storage.

1. INTRODUCTION

       Kunun zaki is a traditional, non-alcoholic and  non-carbonated beverage widely  consumed in Northern Nigeria and is becoming popular in the South .It is consumed at any time of the day by both adults and children, as breakfast drink. It an appetizer and it is commonly served at social gatherings. The ingredients used in its manufacture include, millet (Pennisetum typhoideum), sorghum (Sorghum vulgare), maize (Zea mays), rice (Oryza sativa), spices [ginger (Zingiber officinale), garlic (Allium sativum), red peeper (Capsicum annuum), black pepper (Piper nigrum), clove (Syzygium aromaticum)]. Also Cadaba farinosa, potatoes (Ipomea batatas)(Efiuvwevwere and Akoma, 1995). Tiger nuts (Cyperus esculentus) and groundnut (Arachis hypogea) may be added to sweeten and enrich protein content.

      Kunun zaki is rich in carbohydrates, vitamins and minerals but it is low in protein (Ayo and Okaka, 1998). Sugar may be added instead of pepper to meet the demands of some consumers (Onuorah et al, 1987; Akoma et al 2006). Some consumers consume kunun zaki without sugar or pepper (Adeyemi and Umar, 1994). Kunun zaki is accepted based on its colour (cream) and flavour (millet mixed with ginger flavour).

        Traditionally, kunun zaki is produced by steeping the grains in water, wet milling with spices and sieving, the overall process taking 24 hours (Adeyemi and Umar, 1994). This traditional method has been improved by shortening the processing time to 12 hours by steeping the grains in warm water containing 15% sodium metabisulphate, wet-milling, liquefication and saccharification with enzymes in the grain, filtering, bottling and pasteurization at 80^oC for 30 minutes before refrigeration at 4-8 ^oC (Gaffa and Ayo, 2002). Traditionally produced kunun zaki has a shelf life of about 24 hours (Adeyemi and Umar, 1994) at ambient temperature. The improved method can however extend the shelf life to 8 days after pasteurization followed by refrigeration storage (Osuntogun  and Aboada, 2004) which can last for 90 days when chemical preservation is applied as has been achieved by FIIRO, Nigeria (Haard, 1998). Also instant kunun zaki flour has been produced by Dala Foods Limited Kano, Nigeria and commercialized Kunun Tsamiya, the product being made only from millet. Further work was done by Amazikwu (2007) where she produced instant kunun zaki flours from millet-cowpea malt and millet-soybean malt to enhance protein content and sensory quality. She also carried out sensory evaluation and the samples were rated acceptable by consumers.  However no packaging or storage studies have been carried out on the instant powders and shelf life is also largely dependent upon the storage conditions and packaging materials used. This work is therefore a follow up of the work done by Amazikwu (2007). Against this background, this project was designed to produce instant kunun zaki flours from millet-cowpea malt and millet-soybean malt combinations and store in good flexible packaging material. Specific attention was therefore directed at;

(i) producing instant kunun zaki powders from millet-cowpea malt and millet-soybean malt by steam heating.

(ii) studying the changes in physicochemical and functional properties of the packaged flours during storage.