Effect of processing on the selected properties of cowpea flour to be incorporated into spaghetti

In this study, various types of cowpea flours were produced from germinated, fermented andcooked cowpea or cowpea flour seperately to decrease the antinutritional factors and obtain amore beneficial product. The untreated cowpea flour was also produced. These four types ofcowpea flours were used in the enrichment of spaghetties at different levels (10, 15, 20, 25%w/w). The spaghetti samples were stored at room temperature (~25ºC) for 12 months. Someselected properties of the cowpea flours and spaghetti samples, such as ash, moisture, protein,oil contents and color values were determined. The phytic acid content and total antioxidantcapacity of the spaghetti samples were determined initially, after six months and twelvemonths of storage. The spaghetti samples supplemented with 20% cowpea flours were alsoanalysed for in vitro protein digestibility (IVPD), microbial count (total bacteria, mould andyeast) and gelatinization behaviour over the storage period at room temperature.Addition of cowpea flour increased the protein content of spaghetti up to 15.29% (db) from11.73% (db). The amino acid profile of the spaghetties was also improved based on theknowledge that the best amino acid profile for a cereal product was obtained by combiningthem with legumes. The sensory test results of the spaghetties enriched with cowpea flour upto 25% were not different from that of the control spaghetti generally, with regard tostickiness, bulkiness and firmness. The spaghetties enriched with the fermented cowpea flourhad significiantly higher ?total organic matter? (TOM) values. The enriched spaghetti sampleswere darker in colour than the control spaghetti sample. Cooking had a negative effect on thetotal antioxidant capacity (TAC) of cowpea flours while germination increased the TAC ofthe samples. There was a slight decrease in the TAC values of spaghetti samples during thestorage period. While, the cowpea flour supplement caused an increase in the phytic acidcontent of the spaghetti samples, the decrease in the phytic acid content with respect to timewas about 0.3% for six months period and 1% for twelve months period and was notsignificiantly important for most of the samples (p>0.05).The spaghetti samples were analysed using differential scanning calorimetry (DSC) todetermine the gelatinization behaviour of starch as a component of them. Two endothermicpeaks were observed with significiant differences in the gelatinization enthalpies (∆H) ofcontrol and cowpea added spaghetti samples. The transition peak (Tp) temperatures were inthe range of 66.9-67.9ºC and 86.9-100.4ºC for the first and second peaks, respectively. Thetransition entalpies (∆H) were in the range of 2.41-4.21 J/g and 1.71-3.86 J/g for the first andsecond peaks, respectively. The cowpea flour addition decresed the enthalpy values for starchgelatinization and increased it for protein denaturation. Totaly the heat needed for the cookingof spaghetties increased by the enrichment with the exception of cooked cowpea flour addedsamples that need equal amount of heat with the control spaghetti.Supplementing spaghetti with the cowpea flour did not have a significiant effect (p>0.05) onin vitro protein digestibilities. Though there was a slight variation in aerobic plate count(APC), and mold and yeast counts of cowpea added samples (p<0.05); spaghetti samples werefound to be safe in terms of microbiological quality after one year of storage. The best typesand amount of cowpea flour to be incorporated into spaghetti were proposed to be theunprocessed and than germinated types up to 20% according to TOM values and sensoryresults.Key Words: Cowpea; Differential scanning calorimetry; Fermentation; Germination; Phyticacid; Protein digestibility; Spaghetti; Starch gelatinization; Total antioxidant capacity.