Table 9.1.6 Proximate composition, colour values and functional properties of flours from different botanical sources
Flour
Parameter | Taro | Potato | Soybean | Corn
Moisture (%) | 7.7 ± 0.21bc | 7.5 ± 0.19b | 6.6 ± 0.23a | 8.4 ± 0.16c
Ash,% | 1.2 ± 0.12b | 1.9 ± 0.13c | 3.8 ± 0.19d | 0.71 ± 0.10a
Crude fat,% | 1.0 ± 0.08b | 0.33 ± 0.09a | 1.4 ± 0.07c | 4.3 ± 0.08d
Protein,% | 2.0 ± 0.52a | 2.2 ± 0.46a | 33.5 ± 0.89c | 3.2 ± 0.38b
Carbohydrate,% | 95.7c | 95.6c | 61.3a | 91.8b
Bulk density, g/ml | 0.689 ± 0.028b | 0.998 ± 0.016c | 0.539 ± 0.022a | 0.585 ± 0.020ab
Colour values
L | 85.5 ± 1.04ab | 86.1 ± 1.20b | 84.8 ± 1.01a | 84.4 ± 1.11a
a | 1.5 ± 0.04c | -0.12 ± 0.01a | 0.58 ± 0.05b | 6.4 ± 0.04d
b | 7.5 ± 0.14a | 12.6 ± 0.16b | 21.8 ± 0.12c | 31.6 ± 0.12d
ΔE | 85.9 ± 1.3a | 87.0 ± 1.0ab | 87.6 ± 0.9b | 90.4 ± 1.2c
FC,% | 9 ± 1.0a | 40 ± 1.9c | 58 ± 2.5d | 18 ± 1.2b
Mean ± SD with different superscripts (a-c) in a row differ significantly (p < 0.05) (n = 3) (Kaur et al., 2013)
9.1.5.4 Storage
The important parameters, such as moisture, temperature and hygiene, need to be controlled during storage. Substantial losses can be observed in taro flour during storage. The losses may be due to endogenous, physiological and exogenous factors such as insects, pests, nematodes, rodents, rot bacteria and fungi (Osunde, 2008). Good manufacturing practices can control the exogenous and endogenous factors.
The water activity of the flour can give a prolonged shelf life. It is therefore very important to control moisture content of the foods during processing and storage. Taro flour can be stored for more than a year at 38 °C, with minor changes in acidity, moisture content, colour and also with moderate changes in catalase activities and flavour (Moy et al., 1979). Both ambient and cold storage conditions do not have a significant influence on the physico-chemical properties of taro (Colocasia esculenta [L.] Schott) flour, when stored for 21 days (Baidoo et al., 2014). Taro flour stored for 21 days neither changed its colour or reduced its sugar content; however, water activity increased. Lower aw of the flour is preferred for long-term storage. An increased awduring storage can see the microbial attack and modification of chemical properties, which may lead to irreversible sensory changes (Baidoo et al., 2014). Taro flours kept in polyethylene bags at ambient temperatures may be stored for 3 months without significantly altering their physico-chemical properties, whereas 4 to 5 months is the maximum storage period in polyethylene bags at 4 °C (Aboubakar et al., 2010). So the date line of storing taro flour cannot exceed 3 months kept in polyethylene bags under ambient conditions. To keep good physico-chemical and rheological parameters, flours have to be stored in a sealed polyethylene bag (Aboubakar et al., 2010).
9.1.5.5 Utilization
Taro flour can be potentially used for preparation of noodles (Kaushal and Sharma, 2014), cake (Kumar et al., 2015), bread (Ammar et al., 2009; Sanful, 2011), infant foods (Ikpeme-Emmanuel et al., 2009; Onwulata and Konstance, 2002), cookies (Nip et al., 1994) and extruded snacks (Miranda et al., 2011), etc. Taro is a good base for food preparation for infants because of the high digestibility of its starch, reasonable content of calcium and phosphorus (for bone building), vitamin B-complex and carotene (Onwueme, 1999). Taro flour can be used by the baking industry for the production of bread and other bakery products. It also imparts a distinctive, pleasing flavour and improves toasting qualities, therefore can be used advantageously in crackers, pastries, yeast raised doughnuts, cookies, cakes and cake mixes.
Taro flour can be used as an ingredient in creams, cakes, ice pie fillings, custards and other different products. Snap-type cookie formulations, with taro flour as one of the major ingredients, are developed by first modifying the taro flour and wheat flour ratios, followed by modification of the taro flour, wheat flour, sugar and shortening ratios (Nip et al., 1994). A drop-type chocolate chip cookie formulation has also been developed by replacing 51 % of the wheat flour with taro flour in a commercial formulation (Nip et al., 1994).
The substitution of wheat flour with taro flour in bread-making with substitution levels up to 10 % produce bread that has rheological and organoleptic properties similar to that of wheat flour bread (Ammar et al., 2009). Taro flour can become a spiced flour as a layer material for fried food with a sweet and crispy taste (Minantyo et al., 2014). Taro flour at higher proportions in both extrudates prepared from flour blends made with taro and nixtamalized (TF-NMF) or non-nixtamalized maize (TF-MF) did not produce a significant change of WAI, while the use of higher extrusion temperatures only caused a significant increase of WAI in TF-MF extrudates (Miranda et al., 2011). However, the flour mixtures, from taro and nixtamalized maize flour, produces puffed extruded snacks with good consumer acceptance.
Flours and other products of the milling industry can be subjected to the process of Flour Heat Treatment (FHT) in order to systematically modify their characteristics. This technique ensures the production of countless special products. FHT products can be used for different applications in the food products industry, including breadcrumb coatings, cake flours, binding agents for sausage products and cereal bars, soups and sauces, and many more (www.buhlergroup.com). Different thermal and hydrothermal methods of modifying the flours can be adopted, which may include drum drying, micronizing, turbo thin-layer technique, fluidized bed drying, etc. This treatment is appropriate in reducing or inactivating the enzymes present in the flour, affecting the microbiological status, rheological properties, colour, drying, etc.
9.1.6 Achu
Achu is a mashed taro paste traditionally obtained by cooking fresh corms until softened, followed by peeling and pounding in a mortar to obtain a smooth and homogeneous paste (Njintang et al., 2008). In Cameroon, taro is used in the preparation of a much cherished food, known as achu, which is considered as a highly digestible food. The preparation of achu is limited because of the complexity in the processing, especially its long processing time in pounding the corms and lack of mechanization (Njintang et al., 2007).