The remarkably complex systems that make up the food supply keep revealing many things we didn't know. The complex interactions of different carbohydrates, lipids, and proteins with small molecules provide subjects for studies—and the commercial understanding of these complex interactions are essential to provide safe, nutritious foods. Understanding the structure and function of nutrients, including vitamins and antioxidants, is essential to developing nutritious foods that approach pharmaceuticals. Old wives' tales may be helpful in finding where to look for medical foods, but the proof is in the understanding of structure and interactions with the human system. Some progress is highlighted in this issue.
Interactions in Bread Dough: Softer, Tastier Bread
By treating baker's yeast to a saltwater bath, researchers cut fermentation time and produced softer, bigger loaves. Testing involved 2 sugar levels and a different order of addition. In the paper titled “A Novel Bread Making Process Using Salt-Stressed Baker's Yeast”, researchers found that stressing baker's yeast with a 7% salt solution, then mixing the yeast into a dough produced some novel results. It seems that Saccharomyces cerevisiae, the major microorganism of Baker's yeast, reacts to the osmotic stress from the saltwater dip to adapt to environmental osmolarity variations by adjusting water content, ion fluxes, and glycerol levels in the cell membranes, controlling the internal osmolarity and producing glycerol. Glycerol was recognized as a compatible solute with dough ingredients, based on the observation that an increase in glycerol production and intracellular accumulation also correlated with a decrease in water activity of the medium. The net result is softer bread with improved aroma, taste, and acceptability. S399-402.
Carrots in Space!
Hydroponic carrots offer goodies to astronauts. In “Nutritional, Physical, and Sensory Evaluation of Hydroponic Carrots (Daucus carota L.) from Different Nutrient Delivery Systems”, a group of researchers studied how the hydroponically-grown carrot can be best improved. The beta- and alpha-carotene content of these carrots is high, and the texture, taste, and nutrition of them would allow use as fresh vegetables on a space mission. A couple of different growth systems were used, as were several different cultivars. While some of the carrots looked different, they were acceptable, and produced product with high levels of carotenoids. But it's hard to imagine John Glenn telling Buzz Aldrin to go tend the carrot patch. S403-412.
Coating Eggs Extends Shelf Life
Mineral oil of various viscosities provides a good sealant for shell eggs. In “Selected Quality and Shelf Life of Eggs Coated with Mineral Oil with Different Viscosities”, a group of researchers identified the viscosity of mineral oil that did the best job of slowing loss of weight, freshness, and Haugh number (a measure of albumin freshness) of eggs over time. The egg shell surface has 7000 to 17000 pores that allow moisture and carbon dioxide to get out and air to get inside. Oil can be applied on the surface of shell eggs to seal these pores, reducing loss of carbon dioxide and moisture, and stopping entry of certain microorganisms. Mineral oil coating increased the shelf life of eggs at least 3 more weeks at 25 °C compared to the noncoated eggs. Extending shelf life of eggs by 3 wk is significant when considering the total amount of eggs produced in the United States (7 billion dozen eggs per year). S423-429.
In-Line Monitoring of Bread Dough Possible
According to the researchers who developed the paper titled: “Ultrasonic Investigation of the Effect of Vegetable Shortening and Mixing Time on the Mechanical Properties of Bread Dough”, the dough mixing operation is expected to perform 3 important functions in breadmaking: (1) blend ingredients into a macroscopically homogenous mass, (2) develop the gluten polymers in the dough so that a visco-elastic material with good gas retention properties is created, and (3) incorporate air as discrete bubbles so that they inflate during dough fermentation to produce the aerated crumb structure of the loaf. Several factors, including the mechanical shear from the mixers, the amount and type of fat that can plasticize the dough, and the amount and type of protein and gluten in the flour, can change the effectiveness of mixing, thus changing the characterization of the gas bubbles, stretchiness of the dough, and other quality factors. And consumers like their bread to be identical with the last loaf—variation is not popular unless they decide to try a different type of bread. Ultrasound, set to identify the size and frequency of bubbles in the dough, may be a method of controlling the variation. This paper offers more insight into the relationship between gas bubbles, shortening, and other aspects of this complicated food system. E455-461.
New Approach to the Measuring the Value of Phenolics in Foods
Data relating to antioxidant content compared with phenolic content is recast. This Concise Review paper, titled “Correlations of Antioxidant Activity against Phenolic Content Revisited: A New Approach in Data Analysis for Food and Medicinal Plants” looks directly at phenolic profiles, considering the type of phenolics and their effectiveness in knocking out free radicals. The research team from Texas A&M hypothesized that the current method of estimating the inhibitory capacity of these compounds against ROS, uses data correlating antioxidant activity and phenolics concentration. However, when the R2 values from these correlations are low, it is concluded that phenolic compounds are not responsible for much of the antioxidant activity. While this is sometimes valid, this interpretation does not consider factors such as the differences in the phenolic profiles that can be qualitatively (type of phenolics present) and quantitatively (the relative amounts or proportions of phenolics present) measured between samples. The samples studied can include different genotypes, samples of different maturity stages, or even samples exposed to different postharvest storage conditions. The antioxidant activity of a specific phenolic compound is related with the number of available hydroxyl groups present in the chemical structure. The way that compounds neutralize free radicals will depend on their relative concentrations in the sample matrix. Phenolic compounds can act synergistically, additively, or antagonistically to inhibit reactive compounds. This is an important issue for nutraceutical foods and pharmaceutical compounds. R107-113.
Studies of Lycopene Unveil Knowledge of Carotenoids
In the paper “Lycopene Epoxides and Apo-lycopenals Formed by Chemical Reactions and Autoxidation in Model Systems and Processed Foods”, researchers gained more understanding about the role and method of utility of lycopene and its intermediate products. They concluded that “Epoxidation with MCPBA and oxidative cleavage with KMnO4 provide oxidation products that can serve as qualitative standards, facilitating the identification of the initial, transient products of carotenoid oxidation in foods.” Epoxidation and cleavage to apocarotenals are indeed initial steps in the autoxidation of carotenoids in foods. Epoxidation of lycopene occurs on both the isolated double bonds and the terminal double bonds of the conjugated double bond system, followed by rearrangements, resulting in a large number of lycopene epoxides. These reactions are accompanied by isomerization and diol formation.
The variety of foods that contain lycopene, and their use in diets worldwide, make understanding of what happens to this robust antioxidant during processing very important. And the researchers note that “Extrapolation to foods, however, needs to be done with caution since simple model systems may not reflect the nature and complexity of the multicomponent food matrix and the interactions that can occur. The model systems should mimic the conditions in foods as much as possible.”C674-682.
An Apple a Day May Be Better than We Thought
Apples are the 2nd highest source of dietary antioxidants (next to oranges) in the North American diet, measured using the vitamin C equivalent assay. And apples, when peeled for applesauce and other processed products that don't use apple skin, may provide a useful source of antioxidants and phenolics for commercial use. Researchers reported the phenolic and antioxidant content of a number of different varieties in the paper titled “Phenolic Profiles and Antioxidant Properties of Apple Skin Extracts.” The researchers postulated that, as lipid oxidation, especially the oxidation of polyunsaturated fatty acids, is a significant issue in the food industry impacting both food quality and health of consumers, that apple skin might provide antioxidant compounds that would be useful. They evaluated the phenolic compound composition and antioxidant properties of 21 selected apple genotypes, using an aqueous emulsion system of methyl linolenate. The total phenolic concentrations determined by high-performance liquid chromatography tandem mass spectrometry of methanolic extracts of skins of the apple genotypes varied from 150 to 700 mg/100 g DW. The apple skin extracts, specifically the crab apple varieties such as “Dolgo,” were revealed to be effective inhibitors of oxidation of polyunsaturated fatty acid in a model system and can be considered as a potential source of natural food antioxidants. C693-700.
Solving the Folate Problem
For a number of years, shortage of folate in food systems has triggered the addition of folate to specific foods. This has caused questions about the bioavailability of folate in its available forms, and started the authors of “Folate: A Functional Food Constituent” thinking about better ways to handle the problem of low folate and how to enrich foods in a more natural way. Say the authors, “By a careful testing of the folate production ability of microbial strains used in the production of fermented milk starters, formulations may be optimized for natural enhancement of the folate content in food products, especially as a number of studies have shown that high intakes of folic acid, the chemically synthesized form, but not natural folates, can cause adverse effects in some individuals such as the masking of the hematological manifestations of vitamin B12 deficiency, leukemia, arthritis, bowel cancer, and ectopic pregnancies.” The authors propose that an increase in folate levels in yogurts and fermented milks is possible through judicious selection of the microbial species through bioprospecting native strains of folate-producing microbes from different niches (ethnic foods, fruits and vegetables, vegetation, and such) and cultivation conditions. The food industry can take the next step in using this information for selecting folate-producing strains as part of their starter cultures to produce fermented products with elevated levels of this essential vitamin. The proper selection of probiotic folate-producing strains provides a strategy for the development of novel functional foods with increased nutritional value. R114-122.