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Two Articles I Came Across


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#1 lorka150

 
lorka150

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Posted 03 June 2006 - 01:40 PM

Hey everyone,

I am doing some research for a project, and came across these articles. Thought they were interesting:



http://www.chemistry...f6a17245d830100



Rice Bran and Hypertension

Jim_Kling





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Hypertension (high blood pressure) is a major risk factor for stroke, coronary heart disease, and renal vascular disease. A number of drugs on the market combat hypertension by inhibiting the antiotensin-1-converting enzyme (ACE). ACE activates peptides called angiotensins, and these in turn cause constriction of blood vessels and thus increase blood pressure. Although ACE inhibitors can be effective in lowering blood pressure, they can can also cause severe side effects.
Researchers have recently expended much effort to find bioactive components in food that can reduce the risk of cardiovascular disease. They have found that fruits and vegetables are protective, possibly due to the presence of antioxidants that scavenge reactive oxygen species, which occur in many organs and may play a role in several cardiovascular disease pathways.

One potential source of antioxidants is rice bran, which is the outer layer containing the germ of the grain and is removed during milling and polishing. The bran is 12-13% oil and has high levels of dietary fibers (beta-glucan, pectin, and gum). It is removed because its oils can quickly become rancid and reduce rice's shelf life. However, the health benefits of its fiber and antioxidants have led to the inclusion of bran in a number of health food products.

Recently, researchers showed that black rice bran inhibited atherosclerotic plaque formation in rabbits. In the March 8 issue of the Journal of Agricultural and Food Chemistry, researchers at Tohoku University (Sendai, Japan) and the National Research Institute of Brewing (Hiroshima, Japan) reported that rice bran extracts also reduce hypertension in rats (J. Agric. Food Chem. 2005, 54(5) 1914 - 1920).

The team investigated two rice bran fractions: an ethanol fraction (EF), and a driselase fraction (DF). Driselase is a mixture of enzymes capable of hydolyzing the components of plant cell walls. The researchers performed an extraction of the fiber using 70% ethanol, then filtered off the remaining solid, concentrating the ethanol to produce the EF. They suspended the remaining solids in buffer and subjected them to driselase overnight, then concentrated the liquid fraction to produce the DF. The researchers found that the EF contained much of the lipid component of rice bran, while the DF captured most of the nonlipid components.

When rats that had developed spontaneous hypertension received the fractions as a dietary supplement, both caused the rats to exhibit reduced blood pressure, inhibited ACE activity, and reduced glucose levels, among other effects, compared with rats fed a control diet. The fractions also reduced the rats’ urinary levels of hydroxy-2´-deoxyguanosine (8-OHdG), which is a byproduct of DNA oxidation and a marker of oxidative DNA damage and oxidative stress.

The researchers also conducted in vitro studies to confirm the extracts' inhibitory effects on ACE, and they conclude that ACE inhibition in plasma is the primary mechanism by which bran fractions reduce hypertension. Further experiments revealed that phenols and ferulic acid in the bran fractions contributed to their biological effects. Ferulic acid occurs abundantly in plant leaves and seeds, where it links to lignin and other biopolymers and acts as a strong antioxidant.

Rice bran joins a list of other foods with ACE inhibition properties, including tofuyu (a version of tofu), Indonesian dried-salted fish, and mushrooms.

This article first appeared on March 13, 2006.






http://www.chemistry...f6a17245d830100



When Gluten is Verboten, Rice is Nice

Margaret_Hill





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Pick up a book on breadmaking, and you’re bound to find a whole section that discusses the role of gluten in dough development. Gluten is the substance that gives shape and structure to bread dough as it rises and later as it bakes. Without gluten, the majority of breads that you find at your grocery store would be dense, flat planks, not light and fluffy loaves.
Yet approximately 1% of the U.S. population must avoid gluten completely because their bodies respond adversely to this natural protein found in wheat, barley, and rye. Celiac disease is one manifestation of this, and there are several other types of sensitivities to gluten. Fortunately, by adhering to a diet devoid of any gluten, people with these sensitivities can circumvent all difficulties they encounter with gluten.

This presents a real challenge, however, because Western foods are so heavily wheat-based. Fresh baked goods, boxed cereals, pastas, and a multitude of packaged foods are all typically made from wheat flour. Wheat and other gluten-containing grains also make up the majority of the whole grains recommended by the U.S. Department of Agriculture (USDA) in their 2005 Dietary Guidelines.

According to Mary Schluckebier, executive director of the Celiac Sprue Association, choices do exist for people who must avoid gluten. But, Schluckebier says that creating more choices of nutrient dense foods such as whole-grain gluten-free foods is very much needed. Unfortunately, commercial gluten-free foods have not come nearly as far as other foods in the availability of whole grain.

Ranjit S. Kadan at the USDA Agricultural Research Service in New Orleans set out to change that. Beginning just a year or two ago, Kadan, a food scientist, has been developing a whole-grain rice bread that contains no major food allergens. He had been working on rice fries, an alternative to potato French fries, and recognized the potential that whole-grain rice could have if it could be developed for baking.

Developing rice for baking is far from an easy task, however. Rice does not contain the protein gliadin, which in wheat associates with another protein, glutenin, to form the combination gluten. This two-protein gluten complex forms long, interconnected strands throughout wheat dough, giving it shape and structure. Furthermore, this gluten network traps carbon dioxide produced by yeast, allowing millions of tiny pockets of gas to form within the dough matrix. An illustration of the network forming properties of gluten can be accessed from the Web site: http://www.explorato...read/index.html.

So, if dough made from rice flour does not contain gliadin and therefore cannot form this structural matrix, can it be made to rise like wheat dough? “Yes,” says Kadan, “we’ve been able to make a whole-grain rice bread with taste and texture comparable to any typical commercial wheat or white bread.”

Kadan and his group achieved this by experimenting with an array of rice varieties, by determining the optimal flour particle size, and by optimizing the starch content and the water content. He found that the addition of carboxymethylcellulose increased the viscosity of the rice dough at the baking temperature, allowing it to retain gases to give it the same texture as a wheat bread. All told, his group’s experimental work essentially reinvented bread from the ground up.

Kadan is currently exploring possible partnerships with commercial producers to make his process available to the public. He expects to eventually see the production of a whole-grain rice bread mix that people can buy and prepare in their home bread machines. As well, Kadan anticipates that his process will be adapted for making whole rice grain pastas and pizza doughs by one or more commercial producers.

For more information on celiac disease and other gluten sensitivities and the reseach mentioned in this article, visit the following Web sites:
Celiac Sprue Association
Gluten Intolerance Group
USDA Agricultural Research Service
Whole Grains Council

This article first appeared on June 20, 2005.
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