fnu 232 chapter 10

starch

storage form of energy in plants

flour

made from the endosperm portion of cereal grains (seeds)

what is the most common type of flour?

wheat

what other types of cereal grains can provide flour?

oats, rye, barely, rice, corn

what non- cereal sources can flour be made from?

soybeans, potatoes, cattails, taro, arrowroot, nuts

plants make carbohydrates by using the sun's energy to combine ____________, _________________, ________________ from carbon dioxide and water

carbon, oxygen, hydrogen

how is crumb developed in baked goods?

number and size of air cells, degree of gelatinization, amount of protein coagulation

polysaccharides are broken down into smaller glucose molecules called

dextrin

what do sugar and fat do to baked products?

tenderize

fine crumb

delicate with small, densely packed air bubbles

course crumb

large and irregular air holes

gluten

protein in wheat flour, provides structure in baked products, ability of a product to rise depends on it

what are the 2 proteins in gluten?

gliadin and glutenin

what does gliadin do?

gives bread the ability to rise during baking

what does glutenin do?

responsible for strength and elasticity

what causes gluten expansion?

production of steam and CO2

why do gases rise?

yeast or leavening ingredients, kneading, temperature

when does the baked products structure set?

when the heat from baking coagulates the proteins and gelatinizes the starch

what does opening the door during baking?

it decreases the temperature and causes the product to set prematurely

in cakes and pastries, ____________ formation is not desired bc it will result in a _________ texture

gluten, tough

what are the steps to gluten formation?

hydration and kneading

what are the four types of food reactions to cereal exposures?

baker's asthma, wheat allergy, celiac disease, non- celiac disease

celiac disease

immune disorder resulting in the body producing antibodies to gluten, inflammation damages surface of intestinal wall

gluten free

product containing less than 20 ppm, does not contain wheat, rye, barley

milling (grinding)

process in which the grain kernel's endosperm is ground into a fine powder known as "flour"

what is the protein in cornmeal?

zein- does not mimic gluten, reason for crumbling and compact texture

what is the product of leavening agents in a product?

helps them expand

what is the difference btwn. baking powder and baking soda as a leavening agent?

baking powder is slow, baking soda makes products expand quickly

what does baking soda have added to it?

monocalcium phosphate

what was 1st used to grind grain into whole- grain flour?

mortar and pestle (brand, germ, aleurone, and endosperm weren't removed)

soft wheats

least protein and highest starch content (ideal for fine crumb)

hard wheats

higher protein content (best for making yeast bread)

whole- wheat flour

made from the entire wheat kernel (bran, germ, endosperm)

bread flour

higher gluten content of bread makes it ideal for making yeast breads and hard rolls that require elastic gluten for multiple rising periods

white flour

made only from endosperm

all purpose flour

most widely used in the US

pastry flour

made from soft wheat, preferred by professional bakers

cake flour

pure white, silky- soft texture

high- gluten flour, vital wheat gluten, and seitan

contains wheat proteins and can form gluten

what are non- wheat grain flours containing gluten?

rye and triticale

what are the gluten- free grains?

amaranth, buckwheat flour, cornmeal, masa harina, rice flour, sorghum flavor, gluten- free flour

cornmeal

made from yellow, white, and even blue varieties of corn

what may be added to gluten- free flour to prevent crumbliness?

xanthum gum

what are the types of nongrain gluten- free flours?

tuber- based, legume based (garbanzo bean and soy flour), nut- based (almond meal and coconut)

what are the treated wheat flours?

aged, bleached, phosphated, self- rising, enriched

how are flours aged?

they are stored for several months so it could become naturally bleached by oxygen in the air

what does oxidizing do to the flour?

improves the volume, texture, and crumbed structure of baked goods

phosphated

leavened by baking soda instead of baking powder; increases calcium content

self- rising

AP flour with leavening agent and salt added (1 cup AP flour, 1/2 tsp salt, and 1.5 tsp baking powder)

enriched

white flours with B vitamins (thiamine, niacin, riboflavin, folate, and iron). calcium is optional. fiber and vitamin E are lost in the removal of bran and germ and are not added back

plants serve as the

source of starch granules, which are the plant cell's unit for storing starch

glucose is converted to starch by the __________, and then used for energy or stored in the ________, __________, __________, or ____________

plant, seeds, roots, stems, tubers

what are the common sources of starch?

cereals- wheat, rice, corn / root starches- potatoes, arrowroot, cassava (tapioca)

the wet milling process turns corn into cornstarch. Explain it.

1) dried kernels are softened by soaking them in water containing sulfur dioxide 2) kernels are cracked, extraneous material is removed, cracked kernels are cracked and screened, or sifted down to yield starch and protein 3) protein is removed and starch is filtered, washed, dried, and packaged as cornstarch

what is starch's main use in processed foods?

thickening agent (and gelling)

what foods are typically thickened?

soups, sauces, pie filings, gravies, cream filing, custards

what are the purposes of starch?

thickening agent, edible film, sweeteners, starch syrups

edible film

protective coating for chewing gums, bind foods such as meat products, and as a base on food to hold flavor oil in chocolates

sweetener (dextrose -- dextrose equivalents --maltodextrins)

repeating units of glucose molecules, broken into individual units to sweeten confections, wine, and some canned goods

starch is a ________________ consisting of long chains of repeating glucose molecules linked together either in the form of _________ or _______________.

polysaccharide, amylose, amylopectin

amylose

primarily made up of linear molecules

amylopectin

molecules are highly branched

most starches contain _______ amylopectin and _______ amylose.

75%, 25%

how much amylose do high- amylose starches contain

40- 70%

all starches contain amylopectin but a few consist entirely of ___________________, which are known as ___________________.

amylopectin, waxy starches

starches containing higher levels of amylose tend to _____, whereas starches containing higher levels of amylopectin are considered ___________________, but are gummy.

gel, non- gelling

gelatinization

contributes to viscosity of thickened foods and the structure of baked goods

what are the steps in gelatinization?

heat applied, hydrogen bonds weaken, water penetrates the granule, amylose migrates out of the starch granules, water becomes less available

what happens when amylose migrates out of the starch granules?

hydrogen bonding between water and amylopectin increases

what is the result of water becoming less available during gelatinization?

the mixture is made thicker and more viscous

factors influencing gelatinization

water, temperature, heating time, stirring, acid, sugar, fat

what temperature causes starch granules to thicken?

140 degrees F

starches do not dissolve in

cold water or room temperature liquids

what does heating beyond gelatinization temperatures do?

decreases viscosity

what does acid do during gelatinization?

weakens ability of starches to thicken

what does sugar do during gelatinization?

competes with starch for available water, delays onset of gelatinization, increases required temperature

what does fat do during gelatinization?

delays gelatinization by coating starch and preventing absorption of water

gel formation

sol, gel, 3- D network, retrogradation, dextrinization

sol

fluid starch paste that firms into a semi- solid paste

gel

forms after gelatinized sol has been cooled, usually below 100 degrees F)

as the gels cool, linear amylose molecules lose energy and form strong bonds, creating a _______________ that traps water and increases the rigidity of the starch mass

3-D network

retrogradation

as gel cools, bonds continue to form btwn. amylose molecules, and retrogradation occurs. the pie filing appears to be losing its structure or "leaking" -known as syneresis or "weeping", accelerated by freezing

dextrinization

increase in sweetness, causes starches to lose some of their thickening ability

modified starches

exposed to hydrostatic pressure to reduce its gelatinization temperature and instant starch (corn and tapioca)

instant/ pregelatinized starches

do not need to be heated in water to expand and gel (dry mix puddings- contain modified cornstarch)

resistant starches

resists digestion by enzymes and therefore does not contribute kcals

cross- linked starch

chemically treated starches that have starch molecules linked together with cross- bridges, makes starch more heat- resistant and less likely to lose viscosity when exposed to heat (BBQ sauces, pie filings, bakery glazes, puddings)