LAUSR

BACKGROUND Various foods are known to have beneficial effects on health when consumed whole, however, there is a trend to prepare foods from processed ingredients, and it remains unclear whether the benefits of the whole food are retained. Therefore, the purpose of this study was to examine whether different processing techniques affect the cholesterol-lowering and vascular effects of black beans (Phaseolus vulgaris L.). RESULTS Beans were prepared by overnight soaking and boiling, the standard method, as well as by micronization, extrusion, or dehulling and boiling, and then fine milled. Beans prepared by the standard method were also coarse milled. These five materials were incorporated into semi-purifed diets (30% wt/wt) and fed to spontaneously hypertensive rats for 4 weeks. Body weight, blood pressure and aorta morphology were unaltered by the diets. Fasting total cholesterol was significantly reduced in rats fed micronized beans compared to extruded beans (both fine-milled) or the bean-free diet, while boiling combined with coarse milling lowered LDL-cholesterol. The lack of cholesterol-lowering in rats fed extruded bean compared to micronized was not explained by amount or composition of dietary fibre or resistant starch. Differences in the polyphenolic profile as determined by HPLC were also unable to explain the variations in cholesterol lowering capacity. CONCLUSION The present study demonstrates that processing of black beans alters the health effects observed with the whole pulse, and suggests products prepared with processed ingredients will need to be tested emperically to establish whether the biological effects are maintained in vivo. This article is protected by copyright. All rights reserved.