Fruits PDF - 2004

Understanding Food Amy Brown Chapter 18: Fruits Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Composition of Fruits The cellular structure and pigments of fruits are similar to those of vegetables. Organic acids, pectic substances, and phenolic compounds are also found i...

Understanding Food Amy Brown Chapter 18: Fruits Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Composition of Fruits The cellular structure and pigments of fruits are similar to those of vegetables. Organic acids, pectic substances, and phenolic compounds are also found in some vegetables, but have more relevance to fruits. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Composition of Fruits Organic Acids Common organic acids in fruit include: – Citric acid in citrus fruits and tomatoes – Malic acid in apples, apricots, cherries, peaches, pears, and strawberries – Tartaric acid in grapes – Oxalic acid in rhubarb – Benzoic acid in cranberries Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Composition of Fruits Acidity of Fruits Acids cause most fruits to have a pH value below 5.0. The tartness of fruits is related in part to their acidic content. The least acidic fruits are more bland and sweet in flavor, and those with a pH above 4.5 most often serve as vegetables. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Composition of Fruits Other compounds frequently found in fruit are pectic substances, of which there are three groups: – Protopectin – Pectin (pectinic acids) – Pectic acid Slide Development: Lonnie M. Lowery, Ph.D. Pectin is a general term describing this group of polysaccharides found in fruits. – It acts as a cementing substance between cell walls and is partially responsible for the plant’s firmness and structure. Albedo: The white, inner rind of citrus fruits, which is rich in pectin and aromatic oils. Copyright 2004 Thomson Learning Composition of Fruits As fruit continues to ripen and becomes overripe, all the pectin gradually turns to pectic acid. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Composition of Fruits Phenolic compounds are responsible for the browning and bruising that often occurs in ripening fruit. – These compounds, also known as tannins, are found predominantly in unripe fruits. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Purchasing Fruits Grading Fruit Some fruit producers have fresh fruits graded by the USDA on a voluntary basis. The four grades for fresh fruit are: – U.S. Fancy – U.S. No. 1 – U.S. No. 2 – U.S. No. 3 Slide Development: Lonnie M. Lowery, Ph.D. USDA grading is based on: – Size – Shape – Color – Texture – Appearance – Ripeness – Uniformity – Freedom from defects Copyright 2004 Thomson Learning Purchasing Fruits Fruit consumption is on the upward trend. Not only does it look and taste good, but people feel that it is good for them. There are many varieties available, and selection tips are different for each fruit. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Purchasing Fruits Dates There are two basic classes of dates: – Soft – Semi-dry There are over 100 varieties; however, Deglet Noors constitute 95% of the market. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Purchasing Fruits Processed Fruits Other ways of making fruit available all year are : – Canning – Freezing – Drying Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Preparation of Fruits Inhibiting enzyme activity (enzymatic browning) can be accomplished by: – Denaturing enzymes – Adding acid – Lowering the storage temperature – And/or blocking exposure to oxygen through the use of coatings or antioxidants Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Preparation of Fruits Changes that can occur during heating are: – Color pH Metal Salts Ethylene Gas – Texture Osmosis Slide Development: Lonnie M. Lowery, Ph.D. – Flavor Aromatic compound: A compound that has a chemical configuration of a hexagon. Essential oil: An oily substance that is volatile (easily vaporized), with 100 times the flavoring power of the material from which it originated. Copyright 2004 Thomson Learning Preparation of Fruits Dry-Heat Preparation Baking Broiling Frying/Sautéing Moist-Heat Preparation Stewing/Poaching Slide Development: Lonnie M. Lowery, Ph.D. Preparing Dried Fruit Dried fruit is usually soaked in water and then simmered in a covered pan. Copyright 2004 Thomson Learning Preparation of Fruits Types of Fruit Spreads The most commonly consumed fruit spreads are: – Fruit preserves – Jams – Conserves – Jellies – Marmalades – Butters Slide Development: Lonnie M. Lowery, Ph.D. Except for bananas and melons, most fruits lend themselves well to these methods of preservation. Copyright 2004 Thomson Learning Preparation of Fruits Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Storage of Fruits Many types of fruit are picked and shipped to market in an unripe state because the hardship of transportation damages delicate fruits. Unripe fruit can be left at room temperature in a paper bag until ripe. Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning Storage of Fruits Storing Fresh Fruit Ripe fruit with a high water content is best if consumed within three days of purchase. Once fruit is ripe, storage time may be increased by placing it in plastic bags punctured with air holes, and then in the refrigerator. Slide Development: Lonnie M. Lowery, Ph.D. Storing Canned Fruit Canned fruits keep their quality longer if the cans are stored in a dry place with temperatures under 70°F (21°C). Bulging, dented, leaking, or rusted cans should always be discarded. Copyright 2004 Thomson Learning Slide Development: Lonnie M. Lowery, Ph.D. Copyright 2004 Thomson Learning