Monthly Archives: June 2014

Consumers Changing Attitude to Transgenic Tomatoes?

Tomatoes are a good source of lycopene, vitamin C, vitamin E,
and carotenoids. However, tomatoes have relatively small amounts
of flavonoids compared with other vegetables. The flavonoids are
a subclass of plant polyphenols, which have shown to have healthpromoting
effects. Genetic engineering has been used to enhance
the flavonoid content of fruits and vegetables. For example, a
single CHI gene from Petunia hybrida suffices to increase flavonol
content in tomato peel, while Delilah (Del) and Rosea1 (Ros1)
genes extracted from snapdragon were stacked and introduced to
tomatoes, resulting in an increased anthocyanin content and purple
colored tomato peel.
Consumers, however, generally have formed negative but
vague perceptions of transgenic foods which prevent them from
knowingly purchasing such products. Researchers at Kansas State
Univ. evaluated how the color, flavor, texture, and overall liking of
transgenic tomatoes with enhanced flavonoid content compared
to wild-type tomatoes were evaluated by an untrained consumer
The researchers indicate that although recent studies reflect a
new willingness on the part of consumers to buy transgenic vegetables,
almost no attempts have been made to conduct consumer
taste tests with transgenic tomatoes. The few tests that have been
conducted involved transgenic tomatoes thatwere tested by trained
professionals or small consumer groups with no controls for differences
in sample demographics. This study used an untrained
consumer panel to score flavor and overall liking of between 2
transgenic tomatoes and wild-type tomatoes. The panel reported
no difference in liking of texture or color between the 3 tomatoes.
After participating in the sensory study, 14% of the panelists
changed their attitudes positively toward transgenic vegetables and
96% of the consumers on the panel reported that they would buy
transgenic food if they believed that it would promote health.

For more, see Consumer Sensory Analysis of High Flavonoid Transgenic Tomatoes


State of the Art in Gluten Free Research

The term “gluten” refers to proteins that occur naturally in wheat, rye, barley and cross-bred hybrids of these grains.  The water insoluble proteins, gliadin and glutenin, that form gluten are responsible for the wonderful structure of raised breads.

A 2012 Mayo Clinic survey found that 1.8 million Americans out of more than 300 million have celiac disease, an autoimmune digestive condition that can be effectively managed only by eating a gluten free diet.  In people with celiac disease, foods that contain gluten trigger production of antibodies that attack and damage the lining of the small intestine. Such damage limits the ability of celiac disease patients to absorb nutrients and puts them at risk of other health problems, including nutritional deficiencies, osteoporosis, and intestinal cancers.An additional 18 million people, or about 6 percent of the population, is believed to have gluten sensitivity. Although the disease only impacts a portion of the total population, gluten free products have become popular with the overall consumer public.

According to Mintel, a market research firm, gluten free products had total sales of $10.5 billion in 2013 and were expected to reach more than $15 billion in annual sales by 2016. With everything from vodka to cookies being being marketed as gluten free, there is some confusion over what exactly that means.

In August 2013, the U.S. Food and Drug Administration (FDA) established a federal definition of the term “gluten free” for food manufacturers that voluntarily label FDA-regulated foods as “gluten free.” This new federal definition standardizes the meaning of “gluten-free” claims across the food industry. It requires that, in order to use the term “gluten-free” on its label, a food must meet all of the requirements of the definition, including that the food must contain less than 20 ppm of gluten. The rule also requires foods with the claims “no gluten,” “free of gluten,” and “without gluten” to meet the definition for “gluten-free.”

Food technologists have responded by formulating foods that are gluten free. However, as the authors of a review, in this issue of the journal, on the state of the art in gluten free research indicate gluten-free bread products have a low volume, pale crust, crumbly texture, bland flavor and a high rate of staling. Other gluten-free products have inferior product, for example, pasta having poor texture and sauces which separate more easily.

The estimated prevalence of celiac disease varies from 1 in 100 people to 1 in 300 people worldwide in adults. Currently, the only treatment for those with the disease is avoidance of any food or drink containing gluten. To address this need, food technologists seek to develop gluten-free foods that are similar in character to gluten-containing products. However, as the authors of this review point out, the quality of these products still tends to be poor. This review, by researchers from Ireland, discusses the recent advances in developing foods that are gluten free, focusing on ingredients and processing methods which have been documented to improve the processing characteristics and nutritional properties of gluten-free products.

The best approach to producing a bread of favorable baking characteristics from a highly viscoelastic gluten-free batter, is to use a combination of ingredients. Combinations of chestnut flours, chia flour along with various hydrocolloids have had some success in replicating wheat flours.  Other unique flours that have been investigated include carob germ flour, tigernut flour, lupin seed flour, and various vegetable flours. Along with various flours, different ingredients have been studied to address gluten-free product problems such as inability to retain CO2, dense crumb grain, and poor nutritional content. Such ingredients include various shortenings, whey proteins, hydrocolloids, as well as calcium and iron supplements.

Because of the cost of these various novel ingredients, another avenue of gluten-free research involves processing methods. Flour particle size, mixing time, mixing speed, proofing time, and baking method have been explored. Finding an ideal particle size and flour type has proven to be a fruitful avenue of development. Dough containing flour of a lower particle size reduced dough development times and resulted in smaller loaf volumes. It has been hypothesized that the lower particle size flour caused the creation of a weaker structure, which cannot retain the same quantity of CO2, resulting in smaller volume.

Finally, another interesting approach is the use of lactic acid bacteria and yeasts (sourdough) as a bioprocessing ingredient in gluten-free formulations. The benefits of using sourdough in gluten-free formulations include: the ability to generate enzymes (peptidase) with the capacity to detoxify wheat and rye peptides (peptides responsible for the immune response developed from celiac disease) over long fermentation periods; lactic acid bacteria fermentation requires particular pH conditions; which degrades phytic acid (an antinutritional factor known for binding essential minerals, such as, calcium, iron, and potassium); sourdough fermentation facilitates the extractability of bioactive compounds from the flour; the growth of lactic acid bacteria controls the growth of any other organism present, increasing the shelf-life of the product; inclusion of sourdough into a gluten-free formulation enhances the flavor profile of gluten-free bread; and certain lactic acid bacteria strains can produce long chain sugar polymers, which have the ability to act as a hydrocolloid replacements in gluten-free formulations, creating breads with a softer texture.

For more information, see State of the Art in Gluten-Free Research

Making Makgeolli to Last

Makegeolli is a Korean alcoholic beverage brewed from nuruk or koji, and yeasts. Makgeolli has an alcohol content of 6% to 7% and contains vitamins, sugars, proteins, various organic acids, bioactive compounds, and useful microbes. As fresh Makgeolli contains live microorganisms, it will only keep for about one week. Efforts to increase its shelf life have focused on treatments with heat and hydrostatic pressure, addition of cyclodextrin, chitosan, lysozyme and glycine, and pasteurization, freezing storage, and even irradiation. Most of these methods have drawbacks: too complex, too costly, or too time consuming. There remains a need for an effective preservation method.

A group of researchers in Korea have developed a new preservation method that depends on the antimicrobial activity of grapefruit seed extract against Makgeolli-brewing microorganisms and food-borne pathogens. They found that the addition of 0.1% (v/v) and 0.2% grapefruit seed extract in bottled fresh Makgeolli. They found no significant difference in the pH, or the contents of total acids, ethanol, or methanol in the Makgeolli, compared to the control Makgeolli during an 8 week storage period at 10 °C. The extract decreased both bacteria and yeast significantly without a change in sweetness, bitterness, sourness, turbidity, color, or odor. The results suggest that grapefruit extract can control the growth of Makgeolli-brewing microorganisms and extend shelf life (around 2 weeks), without decreasing overall acceptance.

For more information, see the Antibacterial Effect of Grapefruit Seed Extract (GSE) on Makgeolli-Brewing Microorganisms and Its Application in the Preservation of Fresh Makgeolli