Lecture 14

Lecture 14 - © E.Garcia 2010 FST 1 – Main topics –...

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Unformatted text preview: © E.Garcia 2010 FST 1 – Main topics – Lecture 14 Fruits & Vegetables (cont.) Extending Post Harvest life of produce: ‐ Temperature Control ‐ Modified atmosphere (↓ O2) ‐ Minimize water loss (maintain high relative humidity, use of protective packaging) Temperature control is the most effective way to extend post harvest life of produce; it slows metabolic activity. Different produce have different requirements, so appropriate conditions need to be established for different fruits and vegetables. Eggs Egg structure (see McGee p. 75) Shell color: due to breed. Yolk color: due to feed Egg composition One large egg contains: white yolk (g) (g) Water 28.9 8.9 Protein 3.9 2.7 Lipids 0.06 4.5 → Yolk cholesterol content 200‐220 mg Carbohydrates 0.23 0.61 Plus Vitamins and Minerals Egg white and yolk have many uses. Examples of functional properties of egg components are: – foaming: whites (ex.: in meringues; whites can increase 6 – 8 times in volume when beaten to foam. – emulsifier: yolks (ex.: in mayonnaise) Egg Production. Main commercial hen breed in the U. S. is the white leghorn. Annual egg production: about 75 billion eggs. Egg Grading ( AA, A, B) USDA standards for egg quality are based on both interior and exterior factors: appearance, condition of the shell, quality of yolk, quality of albumen (white). Egg size (jumbo, extra large, large, medium, small, pee wee) is not included in the USDA evaluation of egg quality. Salmonella in eggs 79,000 cases of foodborne illness and 30 deaths occur every year, due to consumption of eggs contaminated with Salmonella Enteritidis. Salmonella can be found inside eggs that appear perfectly normal. Bacteria can also be found on the outside of a shell egg. Fecal material can contaminate eggs through the pores of the shells after eggs are laid, or through cracks on the shell. Some designer eggs are commercially available: eggs which have their composition modified in comparison to standard eggs. This is achieved by modifying the feed composition. Examples: increased vitamin E content and omega‐3 fatty acids enriched eggs. (Note: feed containing fish meal may impart off‐flavors to eggs) Pasteurized shell eggs are also commercially available. Shell eggs are pasteurized (in warm water bath) to destroy Salmonella. Eggs can also be coated with wax, to protect them from outside contaminants. Readings 1. McGee p.353 (from 7th line: “Most of the changes… and “Two styles of ripening..”) 2. McGee p.75‐figure (Egg structure) 3. Egg quality – USDA (pdf file posted on the course web page) 4. Safety after date (pdf file posted on the course web page) 5. Shell eggs (pdf file posted on the course web page) Videos 1. The Hen http://www.aeb.org/egg_industry/egg_facts101/egg_facts101.html 2. The Egg http://www.aeb.org/egg_industry/egg_facts101/egg_facts101.html 3. Egg Processing http://www.aeb.org/egg_industry/egg_facts101/egg_facts101.html ...
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