food sci exam LAB

How and why are recipes standardized?

To ensure consistent quality, yield, and results every time.

Measurement accuracy _________ as more measurements are made

decreases

New measuring devices should have deviation no more than _______%

5%

measuring liquids

use graduated cup with handle and pouring spout

measuring solids

use individual fractional cups

measuring flours

Tends to pack so sift before measurement

1. sift directly into cup

2. sift onto surface then scoop into cup

3. if NOT sifted, remove 2 TBSP per 1 cup

whole wheat flour

Do not sift because particles are too large. Stir with spoon, then scoop into cup without tapping the cup before measuring

measuring granulated sugar

no sifting- just measure

measuring confectioners sugar

sift then scoop intp cup

measuring brown sugar

pack firmly, sugar should maintain shape

measuring solid fats

dry measuring cups packed firmly then level

measuring liquid fats

Use standard graduated measuring cup

flavor

Distinctive taste of food or drink, indicator of the essential characteristics of a food

Descriptive Sensory Tests

Special vocabulary to describe samples.

affective Sensory Tests

Preference or liking of a sample.

Difference tests

Asks panelists to detect differences between samples.

 What does sensory evaluation include?

Sight, smell, taste, texture

what is flavor?

Taste, aroma, mouthfeel

How can we judge flavor?

Can judge overall acceptability of a flavor, specific flavor component (sweetness, tartness, etc), or how flavor of one product compares to another

Descriptive Sensory Tests examples

Usually involves trained panelists, but consumers can also assess.

• Difference Tests examples

• rank order

• Affective Sensory Tests

Hendoic scale

Sensory vs. Objective Tests

Sensory tests use human senses to evaluate food (taste, smell, texture), while objective tests use instruments to measure physical and chemical properties with numerical data

• Supersaturated solution

A solution in which more sugar than normal goes into a solution and dissolves

• Interfering agents

1. To prevent crystallization in amorphous candy

2. Delay and control the size of the crystals in crystalline candy

 What is a supersaturated solution and how do you make one?

• Dissolve a large amount of sugar in some type of liquid by heating. As solution cools, the sugar wants to go back to crystal form making it highly unstable.

• What are examples of interfering agents? (Be specific)

1. Fats: high-fat dairy ingredients

2. Proteins: gelatin

3. Monosaccharides- Acid hydrolysis : cream of tartar that creates glucose and

   fructose from sucrose

4. Monosaccharides- enzymes: invertase that creates glucose and fructose from sucrose

5. Monosaccharides- corn syrup

what type of candy do interfering agents prevent crystallization?

amorphous

what type of candy do interfering agents delay and control the size of crystallization?

crystalline

• -  Crystalline candy

• candies formed from sugar solutions yielding many fine, small crystals such as fudge, divinity, penuche, fondant

sugar concentration

lower

temperature

lower

• Appearance
  

• Appear smooth without lumps, opaque with no off-color areas

• Texture crystalline
  

• Very small crystals with smooth feel on tongue

• -  Tenderness: crytsalline
  

• Firm enough to hold its shape, easy to cut and chew

• Mouthfeel

• smooth

• Flavor
  

• Mild, sweet, accented by flavors like chocolate

• -  Amorphous candy definition:
  

• Candies formed from sugar solutions that do no crystallize such as caramel, taffy, toffee, marshmallows.

sugar concentration- amorphous

higher

temperature

higher

• Appearance
  

• Hard candies should be hard, not sticky and clear. Other candies like caramel should be opaque with no off-color and hold its shape upon cooling and cutting

• -  Texture amorphous
  

• hard candies should be hard, other candies smooth and no apparent graininess

• Tenderness
  

• Hard candies should be difficult to cut or bite but dissolve in mouth. Soft candies like caramel should be soft and chewy

• -  Mouthfeel of amorphous candy
  

• Smooth with no lumps or crystals

• Flavor amorphous

mild, sweet

What effect does the addition of NaCl (rock salt) have on the ice water slurry regarding its temperature?

the freezing temperature decreases

-How does the ice/rock salt/water slurry freeze the ice cream?

It reduces the temp low enough to freeze the cream and milk.

• Gluten
  

structural protein that is essential to breads = Strong protein made kneading + water+ glutenin (elastic) + gliadin (fluid and sticky), high amounts of gluten are favorable in breads, but not favorable in pastries or cakes.

glutenin

elastic

gliadin

fluid and sticky

• Shortened cakes

High fat content, creaming method to make light cake, chemical leaveners like baking powder are used to prevent cake from being too dense. YELLOW CAKE

• foam cakes

Use either no fat or fat only from eggs so that the cake is dry and perfect for soaking. No chemical leaveners added, eggs beaten with sugar to create foam and allow cake to be light and rise, ANGEL FOOD CAKE

•  What level of protein flour should be used when making cakes?

low-protein flour for more soft crumble liek all purpose flour or cake flour which has 8-10% protein

• Flour protein content and resulting texture based on flour type:

o Cake or pastry-low protein content (tender result, less gluten development)

o All-purpose-medium protein content (moderately tender, moderate gluten development)

o Bread-higher protein content (less tender, more gluten development)

o Whole wheat-higher protein and includes fiber (crumbly texture bc of

fiber, prevents gluten development)

- What texture results from whole-wheat flour used in pastries?

Crumbly texture because fiber in whole wheat tears gluten strands which prevents gluten development

• -  What are the leavening agents used in both types of cake?

• o Shortened cakes -baking powder
  o Foam cakes -air whipped in before baking

• -  Functions of ingredients in shortened cakes

o Flour- gluten development and gelatinization of starch for volume and

structure
o Fat-provides structure and flavor
o Sugar-flavor, volume, tenderness
o Eggs-structure,stability
o Liquid-aids in gluten development and gelatinization of starch

o Baking powder-leavening agent

• -  What causes tunnels to form inside baked goods?

• Too much baking powder (leavening agent)

• -  What causes tunnels to form inside baked goods?

• Too much baking powder (leavening agent)

• -  Pastry quality is judged by what two factors?

• 1. Flakiness

2. Tenderness- determined by concentration and distribution of gluten

• -  What texture results from too much gluten development?

tough texture

• -  What texture results from not enough gluten development?

crumbly texture

• -  What determines flakiness in pastries?
  

• determined by the size of fat particle and how evenly spread the fat is

• -  Why does cold fat lead to increased flakiness?

• Less fat is absorbed by flour

• -  Why is fat added before water when preparing pastries?
  

• Protects flour from overhydrating which prevents gluten over-development

• -  What is lamination?
  

• What happens when fat is pressed into “sheets” or layers between strands of gluten before baking. ex- flaky pastry

• Best fat in pastries

1. butter for flavor

2. lard and shortening for texture

• How does oil and butter affect pastries?

1. Oil- leads to mealy texture, easily penetrates flour preventing hydration and

   thus preventing adequate gluten development

2. Butter- tastes good but 20% water in butter leads to too much gluten

   development, but best flavor

• Role of water and heat in pastries

1. Water- forms steam for leavening of pastry, allows for proper gluten

   development, dissolves fat

2. Heat- generates steam, melts fat, sets gluten

• -  What causes too much gluten development?

• Not enough fat, too much flour, excessive mixing

- What causes too little gluten development?

Fat cut too small oil used, too little/too much water (dilution effect), not enough mixing

• Dough
  

• contain more flour and are kneaded, high fat content prevents over-development of gluten, liquid to flour ration is 1:3. EX: tortillas, biscuits

• Batters
  

• goal is to avoid gluten over-development, so they are only mixed briefly- made by 2 different methods

• -  What does hydration do for the development of gluten?

• Pulls glutenin and gliadin in flour from endosperm cells

• -  How does kneading contribute to the development of gluten?
  

• Realigns proteins to form crosslinks (like rubber bands) to give strength. In yeast warms the dough to increase fermentation and co2 gas production

• -  What do leavening agents do?

• Make dough rise

- What are the 3 categories of leavening agents? (be able to recall examples)

1. Air- physical: creates air pockets. EX: beating egg whites/sifting

   flour/kneading/creaming fat and sugar

2. Steam- physical: h20 high in volume as it evaporates and expands, leavening in

   all Batters/doughs, only leavening agent in popovers and creampuffs

3. CO2- chemical: baking soda and powder yield CO2 when mixed with an acid

   in presence of liquid.

   - Biological: yeast

• -  What is the leavening agent used in quick breads? (know examples)

• Air, steam, chemical agents (baking soda or powder). EX: biscuits, tortillas, muffins, etc

• -  How does yeast work as a leavening agent?
  

• Uses sugar and produces CO2 and H2O, yeast can hydrolyze starch

• -  What will kill yeast?
  

• If temp exceeds 135-140F

• -  What 3 enzymes are produced by yeast?

1. Diastase- starch to maltose

2. Invertase- disaccharides to monosaccharides

3. Zymase- monosaccharides to CO2 + alcohol

• -  Know the differences between types of yeast

1. Dry active yeast- dehydrated form of fresh yeast, most common, stored at room temp

2. Fresh yeast- 70% moisture, refrigeration required due to moisture

3. Instant yeast- not completely dehydrated, used commercially, reproduces

   more quicky and dough rises 2x as fast, less flavor

• -  What is necessary for baking soda to produce carbon dioxide?

• Acid must be added and baked immediately

• -  What are some food acids that can be used in conjunction with baking soda?

• Cream of tartar, lactic acid (buttermilk), aconitic acid (molasses), acetic acid (vinegar), gluconic acid (honey), malic acid (apples).

• -  What is baking powder? (baking powder vs baking soda)

• Baking soda with the acid already added + inert filler (cornstarch)

• -  What are the 2 types of baking powder?

1. Fast, single acting: CONTAINS 1 ACID. Commercial use only, bake

   immediate;y bc reacts quickly.

2. Slow, double acting: CONTAINS 2 ACIDS (reacts twice).

• -  What are the different types of breads? (be able to recall examples)

1. Yeast breads- fermented after mixing ingredients. EX: bread, rolls

2. Quick breads- leavened by air, steam, chemical agents (baking soda or

   powder). EX: muffins, biscuits, tortillas

3. Cakes and cookies- higher fat, leavened by chemical agents. EX: cake

   donuts,cookies, cakes

• -  Which type of breads contains the most fat?

• Cakes and cookies

• -  Why are quick breads called quick breads?

• Cooked quickly after mixing

• -  What is important to consider for quick breads?

1. Consistency of raw mixture 2. temperature

• -  What are the 2 methods that are used for different types of batters?

1. Pour method- liquid to flour ratio 1;1, sometimes cooked at high temp to

   produce steam, hen lo to brown crust. EX: pancakes, crepes

2. Drop method- contain more flour and are kneaded, high fat to prevent gluten

   over-development, liquid to flour is 1;2. EX: tortillas, biscuits

• -  Know liquid to flour ratio of different batters and dough

• BATTERS-

  1. Pour is 1;1liquid to flour

  2. Drop is 1;2 liquid to flour

  DOUGH

1. 1;3 liquid to flour

• -  Starch
  

• storage form of energy in plants

• -  Starch pastes

Used to thicken foods

• -  Starch slurry
  

• A colloidal dispersion of water and starch

• -  Whole grain
  

• A cereal or grain that retains bran and germ as well as the endosperm

• -  What is the structure of starch?

• Many glucose units

• -  What is the function of starch in foods?

• Used as thickening agent in foods

• -  What physical properties variations occur in starches?
  

• Thickening power and translucency when added to a liquid, ability to form gels

• -  What are the 2 types of starch?

1. Amylose- linear chain

2. Amylopectin- branched chain