Investigation of the properties of macaroni enriched with wheat germ

In this study, shelf life of whole wheat germ and wheat germ oil was studied and enriched macaroni was produced using raw and microwaved wheat germ. Accelerated shelf life test at 60, 70 and 80 C was used for determination of shelf life of whole wheat germ. Also shelf life of whole wheat germ was studied at 30 and 40 °C and these results were compared with results of accelerated shelf life test. Shelf life studies of wheat germ oil at 30 and 40 °C revealed the fact that whole wheat germ was more stable to oxidative and hydrolytic changes than wheat germ oil. Macaroni was produced from semolina and semolina blended with 15% raw or microwaved wheat germ which their shelf life was determined and stored at room temperature for one year. Samples were analyzed for sensory attributes, cooking quality, color, compressibility, microbial count, in-vitro protein digestibility and gelatinization of starch during storage. Effect of cooking time (10, 20, 30 min) on cooking quality of macaroni was also studied. inResults indicated that protein content of macaroni increased up to 17% with wheat germ addition, as expected. Addition of raw and microwaved wheat germ increased cooking losses and volume of cooked macaroni but reduced weight after cooking. No significant effect (P<0.05) of storage was found on the measured parameters except acidity. Acidity of enriched macaroni samples showed a significant increase during storage. Supplementing durum semolina with raw and microwaved wheat germ provided macaroni with similar results to durum macaroni in compressibility and in- vitro protein digestibility. Enriched macaroni samples were more red and less yellow in color compared to the control sample. Differential scanning calorimetry (DSC) was used to study the extent of gelatinization of starch in macaroni samples and two endothermic transitions were observed. Control macaroni significantly shifted to higher onset (Toi) and peak temperature (Tpi), narrow gelatinization range ( T\) and lower gelatinization enthalpy ( Hi) when compared with semolina. Addition of raw and microwaved wheat germ in to macaroni increased Toi, but lowered the Ti and Hi of the macaroni significantly. The second endothermic DSC peak indicated the increase in amylose-lipid complexation ( H2) of macaroni after enrichment with raw and microwaved wheat germ. In taste panel evaluations, significant difference was found between control and enriched types of macaroni in flavor and appearance (degree of difference was found to be slight) but not in texture and overall scores. Microbial counts of macaroni samples were followed by measuring total number of bacteria, mold and yeast at initial, after six and twelve mounts of storage period. It was found that macaroni samples were safe to eat after one-year storage. Keywords: wheat germ, macaroni, shelf life, cooking quality, sensory evaluation, compressibility, protein digestibility, starch gelatinization, differential scanning calorimetry (DSC).