Industrial Application Briefs

Healthy eating is a major topic for just about everybody, and introduces the subject of medicinal foods and plants. Because, as a profession, we are somewhere between folk medicine and fully defined foods, several of these papers provide another step toward fuller knowledge. Relationships between flavor, efficacy against microbes, and full understanding of food components supply a lot of subjects to study. And there are several new papers on a variety of uses of radiation – looks like the technology is coming into its own.

Better Understanding of Consumer's Reaction to Potassium Chloride May Make Sodium Reduction a Little Easier

Consumers use label contents to select one food over another – and sodium content is one aspect of food constituents that make a difference to consumers. In the paper titled “Taste Properties of Potassium Chloride Alone and in Mixtures with Sodium Chloride Using a Check-All-That-Apply Method”, researchers studied the effect of potassium chloride as a replacement for sodium. This study examined the taste properties of KCl using a check-all-that-apply (CATA) ballot, to determine which terms people use to describe KCl and in what ways this may change in various combinations with NaCl. Results showed that adding KCl to foods, with or without sodium reduction increased salt perception slightly, and “salty” was chosen more frequently when in combination with NaCl. Adding NaCl in a mixture with KCl decreases unpleasant side tastes associated with KCl, such as bitter, chemical, and metallic. The 2005 Dietary Guidelines for Americans (DGAC) recommend that people consume less than 2300 mg sodium per day. But, on average, they consume 3400 mg sodium per day, and several quasi-governmental groups have urged the food industry to reduce sodium, by whatever means possible. In developing strategies to reduce sodium, the relationship between perceived salt intensity and liking is critical, and appears to be more important than the relationship between concentration and liking. In the studies of flavor impact, sodium reduction might be achieved by careful partial KCl replacement, without a loss of gustatory quality. This could help meet consumers’ desires for lower sodium foods. Individual differences in the perception and description of non-salty tastes for KCl were noted. The CATA method appears to be a promising technique for assessing consumer taste perception without the need for traditional intensity ratings. S319–S322

Directing the Maillard Reaction to Produce Pleasurable Flavors

The paper “Response Surface Methodology for Meat-like Odorants from Maillard Reaction with Glutathione I: The Optimization Analysis and the General Pathway Exploration” describes how the reaction condition for optimal meat flavor products is generated from synthetic oligopeptides via the Maillard reaction. The optimal reaction condition is: (A) temperature: 131.53 °C, (B) reaction time: 94.85 min, (C) volume of 0.2 M phosphate buffer: 49.61 mL and (D) initial pH of reactants: 4.79. The priority sequence is: A > D > C > B, and the verification score was 9.1. In foods, the spontaneous Maillard reaction leads to a wide range of characteristic flavor products such as roasted, toasted, caramel-like, and meat-like. Researchers have detected the reactivity of bonded amino acids is different when they are present in peptides because peptides are independent precursors and can directly contribute to the Maillard reaction. Types of amino acids and sugars, pH (acidity), temperature, reaction time, concentration of phosphate buffer, and so on can all affect the end products in Maillard reaction. C966–C974

How Can You Tell if It's Irradiated?

Irradiated foods are safe – and many, if not all, consumers know and appreciate that. But some consumers want nothing to do with it, for whatever reason, and the common acceptance is that consumers who don't want irradiated foods should know what is and isn't irradiated. Labels are useful, but the labels may be applied well after the food is prepared, so methods to ensure what is and what isn't are essential. All methods of identifying foods that have undergone irradiation may be used, but some methods are better than others.

None of a particular existing detection method can be used to authenticate all irradiated food products. Ionizing radiation generates hydroxyl radicals in aqueous or oil emulsion systems and these radicals break acyloxygen bond in food components and form aldehydes, Cn-1 alkanes, short-chain hydrocarbons, CO, free fatty acids, and alcohols. Researchers have found hydrocarbons in irradiated meat, and these hydrocarbons are the major radiolytic products in fat and the hydrocarbons produced are related to the fatty acid composition of fat. There are other markers, too, including different concentrations of carbon monoxide in irradiated frozen chicken meat, beef, and pork, found by using microwave heating to release trapped gas and detecting carbon monoxide in the headspace by gas chromatography. Irradiated meat develops a distinguishing “metallic,”“sulfide,”“wet dog,”“wet grain,” or “burnt” odor. Radiolytic breakdown of amino acids, especially sulfur amino acids, causes most of the off-odor in irradiated meat.

This study was aimed at monitoring the radiation-induced chemical changes, such as production of fat-derived hydrocarbons, gas compounds, and off odor volatiles in commercial sausages with different fat contents during storage at 4 °C, and at evaluating the potential of using these chemical compounds as radiation markers for sausages. In “Potential Chemical Markers for the Identification of Irradiated Sausages”, hydrocarbons, gas compounds, and off-odor volatiles were determined for irradiated (0 or 5 kGy) commercial sausages with different fat contents (16% and 29%) during a 60-d storage period at 4 °C. Total of 4 hydrocarbons (C14:1, C15:0, C16:2, and C17:1) were detected only in irradiated sausages. Dimethyl disulfide was detected only in irradiated sausages and its concentration decreased significantly (P < 0.05) with storage. These compounds may provide potential markers for irradiated sausages. C1000–C1004

Radiation Produces Changes in Gelatin Function from Fish

Gelatin, a biopolymer derived from collagen, is widely used in a variety of industries because of its particular properties, such as its ability to be thermo-reversible. In the paper titled “Ultraviolet-B Radiation Induced Cross-linking Improves Physical Properties of Cold- and Warm-Water Fish Gelatin Gels and Films,” the advantages and disadvantages of fish gelatin under different treatments are outlined. Fish gelatin has some particular uses in foods, because unlike gelatin that may contain pig skin, it is usable in kosher and Halal foods. Gelatin was exposed to ultraviolet-B radiation for doses up to 29.7 J/cm2 and solutions and films were prepared from the granule and characterized. The warm-water gelatin films made from irradiated granules had lower tensile strength but better water vapor barrier properties, possibly because of the UV-induced cross-linking in warm-water gelatin that disrupted helical structures. Fish gelatin can be produced from fish byproducts from cold- and warm-water fish's skins, bones, and fins, which are typically underutilized. For instance, the Alaska fishing industry generates over a million tons of byproducts each year, 60% of which are dumped back into the ocean. E215–E223

More Uses of Irradiation

“Microbial Quality and Safety of X-Ray Irradiated Fresh Catfish (Ictalurus punctatus) Fillets Stored under CO2 Atmosphere” describes the use of low-dose irradiation on catfish fillets stored under CO2. As catfish is a popular item, and as catfish farming grows more popular, reduction of bacteria is essential. Regardless of dose ranges, irradiation showed 2 log reduction on psychrotrophic, anaerobic, and lactic acid bacteria for 24 d. Further post-irradiation reductions of spoilage bacteria were observed. Spoilage bacteria on catfish fillets treated with 2 kGy irradiation regained their growth after 16 d of storage. However, catfish fillets exposed to 3 kGy did not show growth of spoilage bacteria throughout the experimental period. Irradiation (2 or 3 kGy) increased pH and TBARS, and decreased “b” values but produced no effect on water holding capacity and texture. According to the authors, farm-raised channel catfish processed during April 2010 totaled 37.1 million pounds and sales of fresh catfish fillets accounted for 57% of total sales of fresh catfish products. These fillets are known to have a short shelf life, and extending salable, safe periods would be a boon to those who sell the product as well as those who use it. The U.S. Food and Drug Administration has approved the use of ionizing radiation on shellfish, and the petition for use of radiation on finfish is being finalized but it is not yet approved in the U.S. M533–M538

Seasonal Changes in Plants Affect Final Product

“Season's Variation Impact on Citrus aurantium Leaves Essential Oil: Chemical Composition and Biological Activities” reports on the changes in chemical composition and antioxidant activity of: Citrus aurantium (bitter orange) leaves’ essential oils over the course of a year. The samples were taken 5 different times, and essential oils made by hydrodistillation; those were then characterized by.gas chromatography/mass spectrometry and GC/flame ionization detection. Forty-six compounds were elucidated. The main components were linalool (43.2% to 65.97%), linalyl acetate (0.77% to 24.77%), and α-terpineol (9.29% to 12.12%). There were more components found in the samples made from summer leaves. Purified compounds derived from EOs such as carvacrol, eugenol, thymol, and linalool inhibit a wide variety of microorganisms, and by evaluating the variance in the essential oils, researchers add to the basic knowledge of these “natural” compounds. In folk medicine, C. aurantium is used for the treatment of sunstroke, gastrointestinal disturbances; it is also known to be a relaxant. The results of the research demonstrated that seasonal variations produced different chemical composition that led to different antimicrobial activities. This suggests that testing and blending could produce a useful product, if toxicity testing shows no problems. T173–T180

Recent Research into the Purification of Phospholipids from Egg Yolk Provides Purity for Emulsifiers and Stabilizers

Phospholipids (PL) have garnered a lot more interest recently, as their biochemical characteristics as signal transmission messengers, emulsifiers, and stabilizers are seen to be increasingly important. PL are a class of lipids that contain phosphorus in their molecules including phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositols, phosphatidylserines, phosphatidic acid, and sphingomyelin (SM). Both PE and PC with high purity (over 80%) are increasingly demanded in the fields of nutrition, pharmacology, and cosmetics. Improving rapid manufacture of these fractions of egg is important. On a dry weight basis, egg yolk contains 2/3 lipids, which comprise 66% triacylglycerols (TAG), 28% PL, and 6% cholesterol (CH) with its esters. Research into methods and testing is disclosed in “Separation of Phospholipids from Hen Egg Yolk by Short Packed Silica Gel Column Chromatography”. Using the procedures described in the paper, and evaluated high-performance liquid chromatography/ultraviolet detector (HPLC-UV) the PL had purity over 96%. Egg yolk PL are extremely desirable for specialized formulas in nutrition and dietetics: for example, infant feeding and undernourished patients. This work should make the separation and testing of these key compounds both simpler and more economical. C948–C953