Ch. 21 Fruits and fruit preparation

ENZYMATIC OXIDATIVE BROWNING •Occurs in fruits and vegetables

•Prevention? •Acid pH •Reduce oxygen contact •Heat (blanching)

CONSUMPTION

•U.S. Dietary Guidelines •2 cups recommended daily •U.S. supply / disappearance data •1.4 servings of fruit consumed per day •46% consumed fresh •42% consumed as juice •Top in popularity •Oranges, apples, grapes, and bananas

List and be able to recognize fruits that are good sources of vitamin C.

-Oranges -Grapefruit -Lemons -Limes *excellent sources of vitamin C

What are phytochemicals?

-Phytochemicals are nonnutritive plant chemicals that have protective or disease-preventative properties. -Phytochemicals are present in many fruits and vegetables and are identified as being health protectors.

Describe the major changes that occur during the ripening of fruit.

-Release of Ethylene Gas: >Ethylene gas is a ripening hormone produced in small amounts by the cells after the fruit is mature >(1): A decrease in green color and development of yellow-orange or red-blue colors >(2): A softening of the flesh >(3): Development of characteristic pleasant flavors > (4): Changes in soluble solids [sugars and organic acids] -Color: -Softening: -Flavor: -Vitamin content:

Compare the general effects of cooking fruits in water and in sugar syrups. Explain what is happening in each case.

-Sugar syrup= balancing external surrounding so internal sugar from fruit does not leave semi-membrane -Water=leaves fruit withered, sugar and texture lessen since internal water from fruit exits into surrounding water.

What factors are generally monitored during controlled-atmosphere storage of fruits and vegetables? Why is this type of storage effective for some fruits? *Controlled Atmosphere* *Modified-Atmosphere Packaging* *Irradiation*

*Controlled atmosphere*: >Total sums of methods used in controlling the atmosphere delays ripening, it does NOT stop it. -Temperature -Oxygen exchange (High CO2: low O2 levels) >This lowers the rate of cell metabolism and aging of fruit *Irradiation* -At controlled dosages, fruits can be irradiated to delay senescence, reduce mold growth and extend shelf life. It can also be used in combination with modified-atmosphere packaging.

Describe common characteristics of fruit flavor. List four types of chemical substances that contribute to the flavor of fruits.

- - - -

-What is the usual % water found in fruits? -What is the usual % of carbohydrates? -What type of carbohydrate usually predominates in ripe fruits?

- *85% water content* -The caloric value of fruits is usually higher than that of succulent vegetables because of fruits' higher sugar content. (*What is the % though?*) -The chief carbohydrate found in fruit is sugar.

Pigments same in fruit as in vegetables: Things to consider: -What pigments are often present in fruits?

- Chlorophyll (green) - Carotenoids (primarily yellow and orange) -Anthocyanins (red, purple and blue) -Betalains (primarily purple-red) -Anthxanthias (creamy white to colorless) -

What pigments are often present in fruits?

- In fruits, the predominant pigments are the *yellow-orange carotenoids* and the *red-blue anthocyanins*.

Flavor of fruits

- Tart -Fragrant -sweet >Owe their flavor to aromatic compounds. Esters, aldehydes, various alcohols, organic acids, essential oils, sugars, mineral salts and phenolic compounds

Describe several additional methods for cooking fruits.

-Baking=aim is to have fruit hold its form but be tender throughout -Glazing=fruit placed in a saucepan, then covered and cooked over low heat. Cook until tender. Uncovered last minute -Broiling/Grilling=sometimes glaze or sauce are added for flavor -Sautéing=cooking quickly in a small amount of fat. Particularly, butter is preferred b/c it is a flavorful fat.

Suggest an appropriate procedure for cooking dried fruits. Explain why you would recommend this procedure.

-Dried fruits maybe be soaked in water to rehydrate prior to cooking. The higher sugar content [more concentrated] of dried fruit makes the use of additional sweetening unnecessary.

What contributes to the stability of the hazy cloud characteristic of orange juice? >To what treatment may the juice be subjected during processing to maintain cloud formation? >Explain why this treatment is effective.

-Haze = complex mixture of cellular organelles, color bodies, oil droplets, flavonoids, and cell wall fragments that include pectic substances, cellulose, and hemicelluloses -Pectic substances play an important role in stabilizing the cloudy appearance and also contribute consistency. Thus, the citrus juices are *flash heated* to a temperature higher than usual pasteurization temp. to eliminate effects of pectin esterase enzymes (break down cloudiness)

Describe the major steps in the production of orange juice concentrate.

1.) Extraction= (a) Fruit is graded, washed, and sanitized -Fruit is cut in 1/2, then halves are pressed into something similar to a kitchen juicer (rotating burr) (b) Fruit is penetrated by a porous tube and then crushed 2.) Processing= removal of seeds and membranes. In this step, the amount of pulp can be controlled to produce high-or-low pulp juice.

What is a fruit? Define a pome and a drupe. Give examples of each.

All fruits are the products from flowers and are the ripened ovaries and adjacent tissues of plants. - A *pome* is any fruit that has a core. [i.e. apples, pears,] - A *drupe* is any fruit which has a stone or a pit that encloses the seed. ["pitted" dates] -An *aggregate fruit* is one that is developed from several ovaries in one flower. For example, {raspberries, strawberries and blackberries} -*Pineapples* and *figs* are examples of *multiple fruits* that have developed from a cluster of several flowers

From a nutritional standpoint:

Fruits are valuable for vitamin and mineral content, phytochemicals and indigestible dietary fiber or bulk.

Describe the usual characteristics of fruits of good quality and suggest appropriate storage conditions to maintain quality.

Good fruits are usually: - Ripe -Good in color -Free from insect damage -No bruising -No skin punctures -No DECAY

Explain why pigment content should be considered when mixing various fruit juices to make a fruit drink.

Mixing various colored fruit juices may sometimes produce surprising, often unattractive results. -Tin or iron salts from canned juices can cause some unwanted reactions -Metals combine w/ anthocyanin pigments= violet or blue green colors - Pineapple juice contains a small amount or iron from processing procedures, and when added to red/purple fruit juices, reds may become blue and blues may be intensified -Lemon juice (acidic medium) usually intensifies red color of red or blue fruit juices mixtures. -Orange juice is best omitted from combinations of red/blue fruit juices b/c it often creates a brown color when present in large quantities. -

Explain what is involved in modified-atmosphere packaging.

Modified atmosphere packaging modifies the oxygen, CO2 and water vapor levels in the air surrounding a product in package. >A semipermeable film used for packaging allows the natural process of respiration by the "fresh or minimally processed" fruit to reduce O2 and increase CO2 content of the atmosphere surrounding fruit

Why are some fruits treated with sulfur before drying? Describe some effects of this process on nutritive value.

Take peaches and apricots for example: they are treated with sulfur dioxide gas/sulfite solution to prevent darkening of color and kill insects. -As for nutritive maintenance, sulfuring preserves vitamins A & C but affects levels of thiamin [B vitamin]

What special processing that involves enzyme action may be used to produce a sparking clear fruit juice? Describe and explain.

To create sparkling clear fruit juice, *clarification* is employed so as to make the juice less viscous and more filterable via pectinases-(pectin-degrading enzymes). [(cellulose and hemicellulase)]. -This step also