The food potentials of tigernut tubers (Cyperus esculentus) locally know as “aki awusa” in Igbo, ”aya” in Hausa and “ofio” in Yoruba were evaluated. The proximate composition of 100g of raw and processed tigernuts showed that moisture content of tigernuts ranged from 4.19 – 51.93 %, crude protein 2.61 – 10.12 %, ash 0.70 – 1.77 %, crude fibre 7.48 – 13.97 %, crude fat 10.79 – 32.06 %, and carbohydrate 22.73 – 56.85 %. Energy values ranged from 232.31- 487.15 Kcal. Tigernuts contain significant amounts of Mg (95.32 -140.96 mg), K (106.44 – 427.92 mg), P (121.78 – 195.95 mg), Fe (1.60 – 4.03 mg), Cu (0.08 – 0.99 mg), Zn (0.32 – 2.46mg), vitamin C (30.90 – 84.66 mg), vitamin E (2.22 – 5.26 mg), moderate Ca (24.42 – 62.29 mg) and low Na (15.77 – 18.27 mg) content. Processing of tigernuts generally increased carbohydrate but decreased magnesium and sodium values. Malting significantly increased calcium content (85 %) and drying and roasting increased Zn and Cu by 100 %. Physico-chemical and functional properties showed that tigernuts and its products are acidic while viscosity of the products per 100 ml was between 88 – 90 cP, specific gravity 1.01 – 1.07, reducing sugar 0.30 – 0.44 g , foaming capacity 18 %. Foaming stability 5.35 %, emulsion capacity 21.88 %, and emulsion stability 49.38 %. Alcohol content of tigernut wine was between 3.17 – 7.13 %. Fresh tigernuts were utilized in the development of tigernut products (milk, coffee and wine) using household methods such as soaking, drying, roasting, malting, fermentation and freezing. Organoleptic and acceptability assessment of the developed tigernut products showed that there was no significant difference (P > 0.05) between tiegrnut products and their controls in most of the parameters tested. All then products were highly acceptable. Tigernuts products (milk extract and wine) evaluation per 100 ml showed high ascorbic acid (6.18 – 7.8 mg), thiamin (0.80 – 1.25 mg), riboflavin (0.35 – 0.59 mg), vitamin E (0.22 – 0.75 mg) and cyanocobalamin (0.03 – 0.05 ug) content. The result of the microbial count of tigernut products (milk and wine) showed values between 3.0 x 102 – 8.0 x 102 cfu / ml and keeping quality ranged from 6 hours to 10 months.
1.1 Background study
Tigernut (Cyperus esculentum) is a perennial grass-like plant with spheroid tubers, pale yellow cream kernel surrounded by a fibrous sheath. It is also known as yellow nut sedge, earth or ground almonds, “souchet” in French, “ermandeln” in German and “chufa” in Spanish (TTSL, 2005). Grossman and Thomas (1998) reported that chufa came to Spain from Africa. Tigernut is found wild and cultivated in Africa, South America, Europe and Asia. Tigernuts grow in the wild, along rivers and are cultivated on a small scale by rural farmers mostly in the northern states of Nigeria. It is locally called “aya” in Hausa; “aki awusa” in Igbo; “ofio” in Yoruba and “isipaccara” in Effik. Tigernuts are edible, sweet, nutty, flavoured tubers which contain protein, carbohydrate, sugars, and lots of oil and fiber (FAO, 1988). Grossman and Thomas (1998) showed that tigernuts have been cultivated for food and drink for men and planted for hogs for many years in Spain and that the lovely milky elixir is served in health Spas, Pubs, and Restaurants as a refreshing beverage (competing successfully with other soft drinks). Unfortunately, despite these potentials in tigernuts it has been a neglected crop in Nigeria. This probably may be due to inadequate knowledge on its production, utilization and nutritional value.
Tigernut could provide a basis for rural industries in Africa. It is an important food crop for certain tribes in Africa, often collected and eaten raw, baked as a vegetable, roasted or dried and ground to flour. The ground flour is mixed with sorghum to make porridge, ice-cream, sherbet or milky drink. It is mostly consumed raw as snack without knowledge of the food and nutritional quality (FAO, 1988). It has also been found to possess good therapeutic quality (Moore, 2004; Zimmerman, 1987; Farre, 2003; Bixquert, 2003; Valls, 2003). Moore stated that “the expansion of tigernut milky drinks will significantly help the research linking tigernut milk to healthier cholesterol levels and other non-dairy manufacturers. This could also gain a boost from an increased consumer interest in health foods”. Variety of food products can be derived from tiger nut tubers though there is little documentation at large. Various food processing techniques can be applied to tiger nut processing to modify its appearance, develop its natural flavour, stimulate the digestive juices, add variety to the menu, make it easily digestible and bio-available, destroy harmful microorganisms, improve its nutritional quality and prevent decomposition. This project work intends to basically evaluate, promote production and utilization of tiger nuts using various processing techniques.