Consumption of the common bean (Phaseolus vulgaris L.) is associated with beneficial effects on lipid and glucose metabolism; however, the influence of the bean processing method on these health benefits is not well understood.To investigate this, we processed red kidney beans (RKBs), a variety of the common bean, by roasting and boiling and compared the physiological effects of the two preparations in male C57BL/6N mice fed a high-fat diet (HFD). The two RKB preparations differed mainly in their resistant starch content (roasted, 24.5%; boiled, 3.1%). Four groups of mice were fed for 12 weeks on a normal diet or a HFD (45 kcal% fat) supplemented with 10% control chow (HFD control group), 10% roasted RKB, or 10% freeze-dried boiled RKB. We found that intake of roasted RKBs prevented hypercholesterolemia and increased fecal IgA and mucin content compared with the HFD control group, while intake of boiled RKBs improved glucose tolerance. Both RKB preparations suppressed the HFD-associated increase in plasma aspartate aminotransferase and alanine aminotransferase levels, which are markers of liver injury. Mice fed roasted RKBs showed significantly increased hepatic expression of cholesterol 7-alpha-monooxygenase mRNA, suggesting that cholesterol suppression may be due to enhanced bile acid biosynthesis. In contrast, mice fed boiled RKBs showed significantly increased cecal content of n-butyric acid, which may be related to the improved glucose tolerance in this group. These results indicate that the method by which RKBs are processed can profoundly affect their health benefits.
: We investigated the physicochemical properties of starches from rhizomes of two lotus (
Nelumbo nucifera
Gaertn.) cultivars, Shinashirobana cultivar and Kanasumi-line No. 20, harvested at the same farm in Japan. A rapid visco analyser analysis indicated that pasting temperatures of the starches from Shinashirobana cultivar and Kanasumi-line No. 20 were 62.1 and 66.5 °C, respectively, and the peak viscosities of the starch of both lotuses were similar 244 and 240 RVU, respectively. The starch from the Kanasumi-line No. 20 at 60 °C had low viscosity, 16.2 mPa∙s, but the starch from Shinashirobana cultivar had higher viscosity, 2,720 mPa∙s, at 60 °C. The onset and peak temperatures of the differential scanning calorimetry (DSC) curve of the starch from Shinashirobana cultivar were 4–5 °C lower than those of the starch from Kanasumi-line No. 20, although both exhibited similar
ΔH
values (13.4 and 11.6 J/g). The distribution patterns of the branched chain lengths of amylopectin in the two starches indicated that the rate of low-degree of polymerization (DP 5–12) of all branched chains was higher for the starch from Shinashirobana cultivar than that for the starch from Kanasumi-line No. 20. These results suggest that the increased rate of DP 5−12 in the starch from Shinashirobana cultivar is related to the higher viscosity of the starch.
The lotus (Nelumbo nucifera Gaertn.) rhizome is widely cultivated and distributed in Japan. Lotuses cultivated in Japan are classified into at least ten kinds of cultivar based on their morphological characteristics. 1) Chinese lotus is a major product in Japan, with its main production area in Ibaraki Prefecture. According to criteria for vegetable cultivation from the Ibaraki Agriculture Institute 2) , Kanasumi-lines (Nos. 20 and 34) and Kohoku-No-Hikari are the major cultivars derived from the Chinese lotus. The Shina-shirohana cultivar derived from the Chinese lotus is named Kaga lotus and is mainly cultivated in Ishikawa Prefecture. The Kaga lotus is used as an ingredient in traditional local dishes (Kaga dishes). One of the characteristic features of the Kaga lotus rhizome is its high stickiness compared with lotus rhizomes cultivated in other prefectures. Kaga lotus is a very important ingredient of Hasu-mushi (steamed grated lotus ball) in Kaga dishes because of this highly sticky texture. The edible parts of raw lotus rhizome contain 16% carbohydrate, making it the largest component of the rhizome except water. 3) We consider that the starch component of the total carbohydrate is a very important factor governing the high viscosity of Kaga lotus. In this study, we aim to investigate the physicochemical properties of the starch from the Kaga lotus rhizome by comparing it with starch from the Ibaraki lotus rhizome cultivated in Ibaraki Prefecture. Kaga lotus rhizomes cultivated in Ishikawa Prefecture were purchased in May 2011 at a local market (Nonoichi,
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