Six Japonica and three Indica rice samples were considered in this study. Total amino acid composition and protein digestibility were studied in relation to protein component while, amylose content, resistant and damaged starch were considered to assess starch characteristics. Results showed a comparable amino acid pattern and carbohydrate but different protein and starch digestibility. Due to the different botanical origin of samples, the amylose content raged between 15.5 and 25.2 g/100 g d. b. to whom corresponded a wide range of pasting temperatures determined by means of Differential Scanning Calorimetry. Principal Component Analysis, used to perform an exploratory data analysis, evidenced the contribution of some amino acids in recognising samples and this evidence could be usefully employed in breeding programs.Keywords: milled rice, nutrient availability, Italian rice, thermal analysis *To whom correspondence should be addressed. E-mail: acquistucci@inran.it
IntroductionRice is the staple food for half of the world's population. It is currently the most rapidly growing food source in Africa. The rice proteins are rich in glutelins and have relatively high lysine content when compared to other grains. Rice is generally easily digested and absorbed by humans producing high glycemic response; however, genetic characteristics and technological processes can reduce the availability to the enzymic degradation so reducing the glycemic response (Casiraghi et al., 1993).There are more than 20 species of rice (Oryza genus) but only two species, O. sativa and O. glaberrima, offer an agriculture interest for humans. Among different varieties, there is a wide variability for grain shape, size, amyloseamylopectin content and endosperm colour and, although rice is cultivated worldwide (about 100.000 varieties), there is no universal rice quality attribute even though cooked rice texture represents one of the main quality factors. Concerning the nutritional properties, cultivar-specific differences in nutrients content, cultural practices as well as post harvest activities can be responsible for loss of nutrients. For this reason, nutrients content should be among the main criteria used in the selection of rice cultivars for use in areas of food insecurity (Fresco, 2005).Italy is the main rice producer in EU. However, Italian exporters have to face the increasingly competition of other rice exporting countries. Some difficulties for Italian rice exporters are due to the fact that traditionally cultivated rice types do not always suit the taste of the consumer from Central and Northern Europe: therefore, to meet customers' requirements, breeding programmes are in progress to produce indica-type varieties, long and not sticky, as an alternative to the so called Japonica-type (long or short but bold sized types) traditionally cultivated.The first goal of the present paper was to provide additional data on the physicochemical and nutritional properties of rice flours and corresponding starch of some Italian rice varieties i...
