Michael P. Dougherty

Antioxidant-rich foods retard lipid oxidation in extruded corn

ABSTRACT Antioxidant-rich plant materials could provide protection against oxidation in extruded foods and feeds, but their efficacy is not well established. Degermed yellow cornmeal was mixed with 0.02% (w/w) ascorbic acid or quercetin, or with 2% (w/w) spray-dried ginkgo extract, onion powder, potato peels, or wheat bran. The mixtures were processed in a laboratory-scale twin-screw extruder at a feed rate of 227 g/min. Water pump rate was 16 g/min; screw speed was 200 rpm. Mass temperature during extrusion averaged ≈170°C. Samples were cut into small spheres, dried to 5% moisture, then stored in trilaminate bags at 25°C. Ground sample headspace was assayed for hexanal and other volatile indicators of oxidation by gas chromatography. Ginkgo and potato peels significantly darkened the extrudates. Total soluble phenolics, as ferulic acid equivalents, were highest in the ginkgo sample. Volatile compounds were lower in several treatments during storage compared with the control. These findings suggest that m...

Composition and consumer acceptability of a novel extrusion-cooked salmon snack.

The objectives of this study were to develop a value-added jerky-style snack from salmon flesh and to minimize loss of healthful lipids during processing. Three formulations were extruded in a laboratory-scale twin-screw extruder. The base formulation included Atlantic salmon (82%, w/w), sucrose (4%), pregelatinized starch (3%), modified tapioca starch (3%), salt (2%), and teriyaki flavoring (2%). Three oil binding agents (tapioca starch, high-amylose cornstarch, oat fiber) were each studied at the 4% level. Barrel temperature, from feed to die, was 65, 155, 155, and 80 degrees C. Screw speed was 250 rpm. Feed rate was 220 g/min. Extrudates were convection-dried at 93 degrees C for 40 min. A texture analyzer was used to evaluate textural properties. Sixty-three consumers evaluated the hedonic attributes of the snacks. Extrusion cooking did not adversely affect content of omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in Atlantic salmon. The oat fiber formulation had the highest lipid (17.49%) content. The other formulations had higher moisture content. A serving (28 g) of the oat formulation provides 0.6 g EPA + DHA. Snacks containing oat fiber had the highest CIE L* and b* values. Snacks containing oat fiber required greater force to bend, cut, and puncture. The oat fiber formulation had the lowest overall acceptability. This portable snack could appeal to consumers who are interested in the health benefits of fish and omega-3 fatty acids and provide salmon processors with a value-added solution for processing by-products.

Effect of Moisture Content and Screw Speed on the Physical Chemical Properties of an Extruded Crab-based Snack

Crab processing generates by-products that could be used in new value-added products to decrease processing waste and increase profits. In this product development study, the effects of moisture content and screw speed on physical properties and composition of an extruded crab-based snack product were investigated. Corn meal was fortified with 10% ground crab leg and passed through a twin-screw extruder using moisture contents of 25% and 30% and screw speeds of 200, 250 and 300rpm for a total of six treatments, extruded in duplicate. Screw speed and moisture content had a significant (p 0.05) influence on moisture content, expansion ratio, crunchiness and L-value of the extrudate while protein, fat, ash and mineral were not significantly (p 0.05) affected. As screw speed increased, moisture content and bulk density of the extrudates decreased. The snack product extruded at 25% moisture content and 300rpm had significantly different (p 0.05) physical properties compared to all other treatments. Increases in torque and melting temperature were observed for higher screw speed and lower extruding moisture content.

Control of lipid oxidation in extruded salmon jerky snacks.

A shelf-life study was conducted to evaluate the effect of antioxidants on oxidative stability of extruded jerky-style salmon snacks. Deterioration of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) due to lipid oxidation is a major concern for this healthy snack. A control jerky with no added antioxidants and 4 jerkies with antioxidants (rosemary, mixed tocopherols, tertiary butylhydroquinone, and ascorbyl palmitate) added as 0.02% of the lipid content were extruded in duplicate in a Coperion ZSK-25 twin screw extruder. Salmon jerkies from each formulation were placed in 3 mil barrier pouches, flushed with nitrogen, and stored at 35 °C and 75% relative humidity. Lipid oxidation was evaluated as by peroxide value and malonaldehyde content. Other chemical analyses included total fatty acid composition, lipid content, moisture, water activity, pH, and salt. Astaxanthin and CIE L*, a*, b* color were also analyzed at 4-wk intervals. Rosemary inhibited peroxide formation better than did other antioxidants at week 8; no treatment inhibited malonaldehyde levels. All jerkies had lower astaxanthin levels after 8 wk, but rosemary-treated jerky had higher pigment concentrations than did the control at weeks 4 and 8. Protection of omega-3 lipids in these extruded jerkies must be improved to offer consumers a convenient source of these healthful lipids. Practical Application: Salmon flesh can be extruded to produce a jerky that provides 410 mg of omega-3 lipids per serving. Natural antioxidants such as rosemary should be added at levels over 0.02% of the lipid content to help control lipid oxidation. Astaxanthin and CIE a* values correlated well with lipid stability and could be used to monitor quality during storage if initial values are known.

Color influences consumer opinions of wheat muffins

Numerous nonprofit and government organizations promote the consumption of whole grains. The 2005 Dietary Guidelines for Americans recommend that three or more servings of whole grain foods be consumed daily to reduce risks for chronic diseases, yet only 11% of total grain servings were whole grains in the 19992002 United States National Health and Nutrition Examination Survey (NHANES) (2). Several reasons for low consumption of whole grain foods include difficulty identifying whole grain products, cost, perceived poor taste, time-intensive preparation, and limited product availability (1). Confusion exists among health professionals as well. A survey of dietitians in the United States revealed that only 60% of respondents could correctly identify a whole grain food and 42% did not know that a recommendation for whole grains consumption existed (3). Approval of a health claim for whole grains and widespread introduction of whole grain products, including those made with white wheat should help to increase consumption of whole grains (6). The objectives of this pilot study were to determine whether product color affects acceptability and perceived healthiness of wheat muffins by consumers and to assess how providing information on flour composition (whole wheat or all-purpose) influences consumer opinions of those traits.

Characteristics of Formed Atlantic Salmon Jerky

UNLABELLED Smoked salmon (Salmo salar L.) processing may generate large amounts of small pieces of trimmed flesh that has little economic value. Opportunities exist to develop new added-value foods from this by-product. Brining was compared with dry salting for the production of formed salmon jerky-style strips that were then smoked. The formulations also contained brown sugar and potato starch. Salted samples had higher salt concentrations and required less force to break using a TA-XT2 Texture Analyzer. Brined samples contained more fat and were darker, redder and more yellow than the salted samples. Processing concentrated omega-3 fatty acids compared with raw salmon, and the brined jerky had the highest omega-3 fatty acid content. A panel of 57 consumers liked the appearance and aroma of both samples equally (approximately 6.7 for appearance and 6.3 for aroma on the 9-point hedonic scale. Higher acceptability scores for taste, texture, and overall quality were given to the brined product (6.7 to 6.9 against 6.2 to 6.3). PRACTICAL APPLICATION Salmon trim from smoking facilities can be utilized to produce a jerky that is a good source of omega-3 fatty acids, simultaneously adding value and reducing the waste stream.