Medicated Wine This is a special product, developed by blending 18 medicinal plant parts (fruits of ink nut, Indian gooseberry, garlic cinnamon, leaves of holy basil, night jasmine, Malabar nut, roots of belladonna, asparagus, rhizome of ginger, etc.) before fermentation with wine yeast, S. Cerevisiae, into wine. The starch present in purple sweet potato (PSP) was enzymatically saccharified (using commercial thermostable enzymes Termamyl® (0.2 %) and Dextrozyme®GA (1 %)) to fermentable sugars and the homogenized medicinal plant parts were mixed to it at desirable quantities, before subjected to fermentation. The composition of the final product has been presented in Table 5.2. The herbal wine thus prepared was presumed to contain the therapeutic and anti-oxidant properties of PSP, as well as those of medicinal plant parts added as adjuncts (Panda et al., 2013).
Beer Beer was developed by the combination of PSP flakes and grist prepared from barley. Among the beer samples (prepared from 0, 30, 50 and 100 % PSP flakes as adjuncts), the beer prepared from 30 % PSP flakes as adjunct was the most preferred by the trained panellists. The beer is a lighter pink coloured beverage, because of its low anthocyanin content (2.31 mg/100 g). It is lighter in alcoholic content (3.8 %), a “lager” in type. The beer prepared with 30 % PSP flakes had the following compositions: TSS, 3.57 Brix; starch, 0.77 g/100 ml; total sugar, 6.93 g/100 ml; specific gravity, 1.02; pH, 3.05; titratable acidity, 0.76 g tartaric acid/100 ml; lactic acid, 0.10 mg/100 ml; phenol, 0.21 mg/ml; DPPH scavenging activity, 3.15 % at a dose of 250 pg/ml. The PSP beer has an advantage over the beer available on the market (prepared from malt and adjuncts other than PSP) because of anthocyanin content, higher phenolic content and DPPH scavenging activity. Strong correlation among the anthocyanin pigment, phenol and the DPPH scavenging activity in the beer sample confirms the health attributes of the beer. The beer prepared from 30 % PSP flakes+70 % grist was the best as recommended by the sensory panellists (mean value-7), followed by the beer prepared by 50 % PSP flakes+50%grist (mean value-6) (Panda, 2012: Panda et al. 2015). Some of the important novel fermented products developed at the Regional Center of CTCRI, Bhubaneswar have been displayed in Figure 5.1.
Figure 5.1 Novel fermented products prepared from sweet potato at RC–CTCRI, Bhubaneswar: (a) anthocyanin rich wine; (b) herbal wine; (c) beer; (d) lacto juice: (e) curd; and (f) lacto pickle.
5.2.7 Fermented Foods from Yams, Taro and Cocoyam
5.2.7.1 Fermented Yam Flour ("Amala")
Amala is a popular West African food made from rehydrated fermented yam flour. Fermentation of yams to produce flour has been found to improve product quality as well as to remove inherent coloration problems associated with the acceptability of the processed product (Achi, 1999). The moisture, protein and fat contents of the fermented flour are in the range of 7.0–7.6 %, 2.0–3.5 % and 0.3–0.4 %, respectively, depending on the varieties (Achi, 1999; Akingbala et al., 1995). Pretreated soy flour was used to replace 10,20,30 and 40 % of fermented yam flour as a protein supplement. The protein content of the yam and soy mixture increased from 3.5 % in the control to 19.7 % for 40 % soy fortification (Achi, 1999; Achi and Akubor, 2000). Similarly, a nutrient-rich fermented product was prepared using composite flours of maize and fermented yam beans flours (Nnam, 2001).
5.2.7.2 Poi
Poi is a fermented food prepared from colocasia (taro) roots traditionally in Pacific Islands (Matthews, 2000). The LAB like Lactococcus lactis, Lactobacillus plantarum, Leuconostic lactis, Tetragencoccus halophilus and Weissela confusa play a key role during fermentation, and provide taste and characteristic aroma to the product as well as improved shelf life (Huang et al., 2003). It is high in vitamins, minerals and enzymes and also reported to possess tumour specific-anti-cancer properties (Brown et al., 2005).
5.2.7.3 Sapal
Sapal is a traditional fermented food made from taro, which is popular on the northern coast of Papua New Guinea and nearby offshore islands. It is made by mixing cooked, grated taro corm with coconut cream to the extent of 5: 1 and allowing it to ferment at ambient temperatures. The sapal has a firm texture with almost jelly-like consistency. The fermentation of taro into sapal was primarily due to lactic acid bacteria such as Leuconostoc mesenteroides or Leuc. paramesenteroides, which reached populations of 1.6 × 10’ cfu/ml in the final product (Gubag et al., 1996). Traditionally, sapal is made seasonally in large quantities on social occasions and for the exchange of gifts with neighbours.
An alcoholic beverage prepared by semi-solid fermentation of colocasia using steamed or autoclaved fresh colocasia grits was also reported (Cai and Nip, 1990).
5.2.7.4 Kokobele
Kokobele, a dried fermented product, prepared from fermented cocoyam (Xantho-soma sugittlfolium) tubers, is a common food in the Ondo State of Western Nigeria. The cocoyam tubers are peeled, washed, sliced and steeped in water at room temperature, and left to ferment for 2–3 days. At the end of fermentation, the steep liquor is drained off and discarded, while the cocoyam slices are sun-dried for 3–5 days and then milled into flour, giving rise to kokobele. It is usually reconstituted in water and boiled with pepper, tomatoes, palm oil, fish and spices to enhance its flavour (Iwuoha and Eke, 1996).
5.2.8 Food Additives Production
Starch, flour and bagasse from root and tuber crops serve as a substrate for production of several food additives. These are mostly organic acids, monosodium glutamate, soy sauce, etc.
5.2.8.1 Organic Acids
Lactic and citric acid have several applications in the food industry. LA can be produced by Lactobacillus sp. from potato and sweet potato flour (Panda and Ray, 2008). Cassava or sweet potato starch has been used as a substrate for citric acid production using Aspergillus niger in SSF (Bindumole et al., 2000; Zheng et al., 1999). The process necessitates the initial breakdown of starch to sugars before these sugars are fermented by moulds, for example A. niger to citric acid. In Sichuan Province, China, the largest sweet potato growing area of the country, citric acid is the fourth-most important product from sweet potato after starch, noodles and alcohol (Jiang et al., 1993). In the food industry, citric acid is added as a flavour enhancer or preservative in a wide range of products, particularly soft drinks. In Japan, a drink consisting of a mixture of citric acid from sweet potato and ascorbic acid crystals, which is added to water to taste, has been commercialized (Woolfe, 1992).