What is biodiesel?

Monday, February 2, 2009

Biodiesel is the name of a clean-burning, non-toxic alternative fuel made from vegetable oils that can be used in compression-ignition (diesel) engines. Since soybean oil is the dominant oil produced in the U.S., the development of biodiesel has focused around soy oil. One bushel of soybean produces about 1.5 gallons of biodiesel.

Biodiesel can be used in its pure form, also known as neat biodiesel, or B100. Biodiesel can also be blended at any level with petroleum diesel to create a biodiesel blend. The most common mix is a 20:80 blend of biodiesel to petrodiesel. This blend is called B20.

The name "biodiesel" was introduced in the United States in 1992 by the National SoyDiesel Development Board (now the National Biodiesel Board), which has pioneered the commercialization of biodiesel in the U.S.

What is NOT biodiesel

Blends of biodiesel and diesel fuel. Biodiesel is often mixed with petroleum-based diesel fuel. When 20% biodiesel is blended with 80% diesel fuel, this blend is known as B20. Some people mistakenly believe this blend is biodiesel.

Raw oils: Raw vegetable oil cannot meet biodiesel fuel specifications, it is not registered with the EPA, and it is not a legal motor fuel.

Ethanol-diesel blends (E-diesel)

How is biodiesel made?

Biodiesel is made through a simple refining process called transesterification. The process involves mixing methanol with sodium hydroxide, then mixing that with an oil such as soybean oil. The final products are methyl esters (biodiesel) and glycerine. Glycerine is a valuable material used in the manufacture of soaps and other products.

Methyl or ethyl esters can be produced from vegetable and tree oils, animal fats, and/or used oils and fats.

Some advantages of biodiesel

1. Biodiesel fuel (B100) burns much cleaner than petroleum fuel. The exhaust emissions of sulfur oxides and sulfates, the major components of acid rain are essentially eliminated compared to diesel. Biodiesel is comprised of mid-carbon chains, which burn more completely than petroleum fuel. That is why there is a substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter compared to emissions from diesel fuel.
2. Biodiesel has exceptional lubricating qualities. Use of biodiesel or biodiesel blends have been shown to contribute significantly to the longevity and cleanliness of diesel engines.
3. In new engines, biodiesel fuel consumption is similar to that of petrodiesel. In used engines, fuel economy substantially improves due to continuous cleaning effect of biodiesel.
4. Biodiesel is biodegradable and nontoxic when used in its pure form (B100). For the 20% and lower blends, the diesel fuel portion of the blend determines the toxicity and biodegradability. Biodiesel fuel and fuel blends smell better than conventional diesel - a value to those who work in close proximity to the fuel.
5. Biodiesel is especially promising as a marine engine fuel. As a biodegradable, non-toxic fuel, biodiesel can help prevent damage to marine environments such as wetlands, marshes, rivers, and oceans.
6. Biodiesel is a domestic, renewable resource that strengthens the domestic agricultural economy.
7. The production of soy-based biodiesel has a positive energy balance (as much as 3:1), due to the high energy value of ester-based feedstock's, the low-energy requirements of the conversion process, and the nitrogen-fixing characteristic of soybean.
   

Where to get biodiesel

Biodiesel is available nationwide. It can be purchased directly from biodiesel producers and marketers, petroleum distributors, or at various public pumps.

Phytoestrogens Soybeans

Monday, November 17, 2008

Soybeans contain isoflavones called genistein and daidzein, which are one source of phytoestrogens in the human diet. Because most naturally occurring estrogenic substances show weak activity, normal consumption of foods that contain these phytoestrogens should not provide sufficient amounts to elicit a physiological response in humans.

Plant lignans associated with high fiber foods such as cereal brans and beans are the principal precursor to mammalian lignans which have an ability to bind to human estrogen sites. Soybeans are a significant source of mammalian lignan precursor secoisolariciresinol containing 13–273 µg/100 g dry weight. Another phytoestrogen in the human diet with estrogen activity is coumestans, which are found in beans, split-peas, with the best sources being alfalfa, clover, and soybean sprouts. Coumestrol, an isoflavone coumarin derivative is the only coumestan in foods.

Soybeans and processed soy foods do not contain the highest "total phytoestrogen" content of foods. A study in which data were presented on an as-is (wet) basis per 100 g and per serving found that food groups from highest to lowest levels of total phytoestrogens per 100 g are nuts and oilseeds, soy products, cereals and breads, legumes, meat products, various processed foods that may contain soy, vegetables, and fruits.

Women
A 2001 literature review suggested that women with current or past breast cancer should be aware of the risks of potential tumor growth when taking soy products, based on the effect of phytoestrogens to promote breast cancer cell growth in animals.

A 2006 commentary reviewed the relationship with soy and breast cancer. They stated that soy may prevent breast cancer, but cautioned that the impact of isoflavones on breast tissue needs to be evaluated at the cellular level in women at high risk for breast cancer.

Men
Because of the phytoestrogen content, some studies, but not all, have suggested that there is an inverse correlation between soybean ingestion and testosterone in men. For this reason, they may protect against the development of prostate cancer. A theoretical decrease in the risk of prostate cancer should, however, be weighed against the possible side-effects of decreased testosterone, which are still unclear. The popular fear that soybeans might cause reduced libido and even feminine characteristics in men has not been indicated by any study; the popularity of the notion seems to be based on the simplistic misapprehension that estrogen and testosterone have a simple, inverse relationship in sexual hormone systems and sex-related behaviour. Their interplay is very complicated and largely still unknown.

Studies published in July 2008 show that Soy products and, more specifically, the phytoestrogen they contain might lower a man's sperm count.

Soy allergy

Allergy to soy is often said to be rather common, and the food is listed with other foods that commonly cause allergy, such as milk, eggs, peanuts, tree nuts, shellfish. However, a critical review of medical literature reveals surprisingly little solid information on the topic. The problem has been reported amongst younger children and the diagnosis of soy allergy is often based on symptoms reported by parents and/or results of skin tests or blood tests for allergy. Only a few reported studies have attempted to confirm allergy to soy by direct challenge with the food under controlled conditions. In these circumstances it is clear that skin/blood tests considerably overestimate the problem, as do parental reports. It is very difficult to give a reliable estimate of the true prevalence of soy allergy in the general population. To the extent that it does exist, soy allergy may cause cases of urticaria (hives) and angioedema (swelling), usually within minutes to two hours of ingestion of the food. In rare, severe cases true anaphylaxis may occur, a condition that is much more common with allergy to foods such as peanut and shellfish. The reason for the discrepancy is likely that soy proteins, the causative factor in allergy, are far less potent at triggering allergy symptoms than the proteins of peanut and shellfish. An allergy test that is positive demonstrates that the immune system has formed IgE antibodies to soy proteins. However, when soy is ingested proteins must evade digestion and be absorbed in a form capable of triggering allergy and also in sufficient quantities to reach a threshold to provoke actual symptoms. The low potency of soy proteins as allergens may help explain why allergy skin/blood tests suggest that soy allergy is common, yet few cases are confirmed when the food is eaten under observation.

Soy can also trigger symptoms via food intolerance, a situation where no immunologic (allergic) mechanism can be proven. One scenario is seen in very young infants who have vomiting and diarrhoea when fed soy-based formula. The symptoms resolve when the formula is withdrawn and recur when it is re-administered. Older infants can suffer a more severe disorder with vomiting, diarrhoea that may be bloody, anemia, weight loss and failure to thrive. The commonest cause of this unusual disorder is a sensitivity to cow's milk, but there is no doubt that soy formulas can also be the trigger. The precise mechanism is unclear and it could be immunologic, although not through the IgE-type antibodies that have the leading role in urticaria and anaphylaxis. Fortunately it is also self-limiting and will often disappear in the toddler years.

Promotion as health food
Soy consumption has been promoted by natural food companies and the soy industry's aggressive marketing campaign in various magazines, television ads and in health food markets. Research has been conducted examining the validity of the beneficial health claims with regard to the increase in consumption of soybeans which mimic hormonal activity.

A practice guideline published in the journal Circulation questions the efficacy and safety of soy isoflavones for preventing or treating cancer of the breast, endometrium, and prostate (although the same study also concludes that soy in some foods should be beneficial to cardiovascular and overall health) and does not recommend usage of isoflavone supplements in food or pills. A review of the available studies by the United States' Health and Human Services' Agency for Healthcare Research and Quality (AHRQ) found little evidence of substantial health improvements and no adverse effects, but also noted that there was no long-term safety data on estrogenic effects from soy consumption.

Brain
Estrogen helps protect and repair the brain during and after injury. The mimicry of estrogen by the phytoestrogens in soy has introduced a controversy over whether such a replacement is harmful or helpful to the brain. Several studies have found soy to be harmful for rats. Nevertheless the cited study was based on rats fed with concentrated phytoestrogens and not common soybeans. The common amounts of phytoestrogens in soy beans are not to be compared to concentrated estrogen. One study followed over 3000 Japanese men between 1965 and 1999, and that showed a positive correlation between brain atrophy and consumption of tofu. This study by L.R. White, et al., from the National Institute of Aging, NIH, was rejected as not credible by the Food and Drug Administration.

Carcinogen
Raw soy flour is known to cause pancreatic cancer in rats. Whether this is also true in humans is unknown because no studies comparing cases of pancreatic cancer and soy intake in humans have yet been conducted, and the doses used to induce pancreatic cancer in rats are said to be larger than humans would normally consume. Heated soy flour may not be carcinogenic in rats. Existing cancer patients are being warned to avoid foods rich in soy because they can accelerate the growth of tumours.

Iron
One single small-scale study published in 1995 concluded that "a vegetarian diet that is rich in soybean products and restricted in animal foods is limited in bioavailable iron and is not adequate for maintaining iron balance in men and women".