ARS | Publication request: DETERMINATION OF STARCHES AND DIETARY FIBER POLYSACCHARIDES IN COOKED DRIEDBEANS: COMPARISON OF DIFFERENT TEMPERATURES AND DMSO TREATMENTS

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 9, 1997
Publication Date: N/A

Interpretive Summary: Legumes are known to contain significant amount of dietary fiber (DF). According to the nation's latest food consumption trend as appeared in Agweek Magazine, commodities such as dry edible beans, sugar beets, pasta and potatoes have increased or shifted supply to match growing consumer demand. Until recently, starches that are naturally present in foods are believed to be completely digested by human gastrointestinal secretions. Now, it is accepted that certain amount of starch (resistant Starch) in some foods are not digested; therefore, pass into the colon and are fermented as other DF sources. In this study, we determined the starch content of 2 brands of 5 cooked dried beans (black beans, Great Northern beans, navy beans, pink beans, and pinto beans) using two different autoclave temperatures with or without DMSO. From the starch values obtained with two of the pretreatments, we were able to estimate the amount of resistant starch in the test samples. Results will be useful to food analysts who are in need of simple and reliable method for determining resistant starch as a separate entity from dietary fiber; nutritionists and health professionals who are interested in data on various components of DF; food processors and consumers.

Technical Abstract: Cooked dried beans contain appreciable amount of starches that escape digestion by human gastrointestinal enzymes. Such "resistant starch" possess physiological characteristics similar to certain types of dietary fiber. We analyzed 2 brands of 5 cooked dried beans using two different autoclave temperatures with or without DMSO. Starch as glucose and dietary fiber polysaccharides (DFP) as neutral sugars were determined according to a modified fiber method developed in this laboratory. Results showed that autoclaving at 130 C (T- I) or autoclaving at 121 C in the presence of DMSO (T- II) were quite similar and yielded higher starch and lower DFP values as compared to autoclaving at 121 C (T- III). Starch values ranged from 24.7 to 40.0 g/100 g dry weight for all beans in T- I, from 26.7 to 36.6 g/100 g for those T- II, and from 12.3 to 24.0 g/100 g for those in T- III. Resistant starch content calculated as the difference between T- I and T- III varied between 10.8 g/100 g for Great Northern beans and navy beans of brand A and 20.5 g/100 g for pinto beans of brand B. Sum of neutral sugars ranged from 13.0 to 24.6 g/100 g for those in T- I, from 11.4 to 19.6 g/100 g for those in T- II, and 26.4 to 34.2 g/100 g for those in T- III.