Tropical root and tuber crops [cassava, sweet potato, yams, colocasia (taro), etc] are important staples for food security for about a fifth of the world population. Bulk of cassava in Africa and Latin America are processed into fermented foods and food additives such as organic (acetic, citric and lactic) acids, monosodium glutamate, etc. The fermented foods from cassava are gari, fufu, lafun, chickwanghe, agbelima, attieke and kivunde in Africa, tape in Asia and 'cheese' bread, and 'coated peanut' in Latin America. Lactic acid bacteria and yeasts are the major group of micro-organisms associated with cassava fermentation. Similarly, sweet potatoes can be fermented into soy sauce, vinegar, lacto-juices, lacto-pickles and sochu (an alcoholic drink produced in Japan), and yams into fermented flour. Most of these fermented food products are functional foods rich in phytochemicals, dietary fibres, anti-oxidant compounds (b-carotene, anthocyanin, etc) and probiotic components (lactic acid bacteria and yeasts).

Purple sweet potato (PSP) is a special type of sweet potato having high anthocyanin pigment in the root. The starch contents of PSP (root ⁄ water homogenised in 1:1 ratio) were enzymatically saccharified [using commercial thermostable enzymes Termamyl Ò (0.2%) and Dextrozyme Ò GA (1%)] to fermentable sugars, and the filtrate was ameliorated with cane sugar to achieve 20°Brix, for subsequent fermentation into a red wine using 2% yeast (Saccharomyces cerevisiae) as starter culture. The wine had the following proximate compositions: total soluble sugar (TSS), 2.25°Brix; starch, 0.15 g per 100 mL; total sugar, 1.35 g per 100 mL; TA, 1.34 g tartaric acid per 100 mL; phenol, 0.36 g (caffeic acid equivalent) per 100 mL; anthocyanin, 55.09 mg per 100 mL; tannin, 0.64 mg per 100 mL; lactic acid, 1.14 mg per 100 mL; ethanol, 9.33%(v ⁄ v); and pH, 3.61. 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of the wine was 58.95% at a dose of 250 lg mL )1 . Principal component analysis reduced the eleven original analytical and proximate variables (TSS, starch, total sugar, TA, phenol, anthocyanin, tannin, lactic acid, ethanol, pH, DPPH) to four independent components, which accounted for 76.65% variations. Sensory evaluation was carried out by sixteen trained panellists on various attributes such as clarity, colour, viscosity, odour, flavour, spritz and finish. Independent 't' test confirmed that all the sensory attributes of the PSP wine scored closely (within 10% variation) to that of a commercial grape wine. The red wine produced contains essential antioxidants and acceptable sensory qualities.

Sweet potato (SP) is an important root crop grown all over the world and consumed as a vegetable, boiled, baked or often fermented into food and beverages. The grated SP roots [non-boiled and fully boiled (boiled in water at 100°C for 15 min) were treated with 0.05% of commercial pectinase enzyme (Pectinex, Novoenzyme) in order to extract the juice. The fresh juice was inoculated with Lactobacillus plantarum MTCC 1407 culture at 28 ± 2°C for 48 h to produce lacto-juice (LJ). The anova analysis of analytical data revealed that there was significant effect of boiling conditions (fully boiled and non-boiled) on pH [F (1, 4) = 220.5, P < 0.001), TA [F (1, 4) = 78.89, P < 0.01], starch [F (1, 4) = 26.63, P < 0.01), total sugar [F (1, 4) = 61.36, P < 0.01) and anthocyanin [F (1, 4) = 32.86, P < 0.01) but not on reducing sugar [F (1, 4) = 2.48, P = 0.19). Sensory evaluation rated the SP LJ acceptable based on texture, taste, aroma, flavour and after taste. LJ prepared from fully boiled roots with 10% cane sugar was most preferred by a consumer's panelist based on Linear Discriminant Analysis. Principal component analyses (PCA) reduced the seven original analytical variables to three independent components (factors), which accounted for 99.9% of the total variations. Similarly, six original sensory variables were reduced to two independent components, which accounted for 65.7% of the total variations.

Sweet potato (SP) is an important root crop grown all over the world and consumed as a vegetable, boiled, baked or often fermented into food and beverages. A curd-like product was prepared by fermenting boiled bcarotene-rich SP puree and cow milk with curd (starter) culture (Lactobacillus bulgaricus, Streptococcus lactis, Streptococcus diacetilactis, etc.). There were not much variation in pH (3.6-3.9), titratable acidity (10-11.8 g kg )1 curd) and lactic acid (LA) (7.9-5.3 g kg )1 curd) contents in SP curd consisting different concentration of SP puree. However, curd with 12-16% SP puree was most preferred by a consumer's panellist. The addition of SP puree (12-16%) made the curd quite firm and imparted flavour, body/texture, minerals, nutrients, antidiabetic substances, b-carotene pigments (antioxidant), dietary fibres and starch (carbohydrate source). The LA bacterial counts in the curd after 18 h of fermentation having 8% and 16% SP were 7 · 10 7 and 14 · 10 7 (CFU mL )1 ), respectively. The consumer evaluation scores ranged from 7 to 8 (in a hedonic scale of 1-9), from moderate liking to very much liking of the SP curd, taking into consideration the sensory attributes such as colour, texture, flavour, sweetness, appearance, etc. Principal component analysis (PCA) reduced the fourteen original analytical (proximate) variables to four independent components (factors), which accounted for 97% of the total variations. Similarly, PCA analysis reduced the seven original sensory attributes to three independent components that accounted for 70% of the total variations.

No abstract