Unformatted text preview: Di- & Complex CBOH
! Glucose (reminder)
! ! ! G.M. Smith
Food Science & Technology Monosaccharide Hexose Sweet (!"#$ó%, # = &) Relation to other sugars
! ! ! fructose galactose galacturonic acid
FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 Maltose
! Structure of Maltose Termed “malt sugar”
! Think of the malt shop, malted milk, maltflavored cereal, candy, malting & brewing ! ! It is prepared by yeasts or enzymes acting upon starches. It is a disaccharide - 2 glucose moieties FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 Lactose
! Dairy History
! ! A disaccharide from mammalian milks Composed of glucose & galactose It is commercially prepared from whey 1/6 sweetness of sucrose Has low solubility (NB)
FST10 ©GMS/GFR 2010 Derivation of common words in dairying Latin lac = milk
! ! Led to lactation, lactose Led to galaxis to galaxy to galactose ! !"#" = gala = milk
! ! ! ! ! ! Is it an accident that our galaxy is the Milky Way? Hmmmm… reminds me of Monty Python’s “Galaxy song” (Eric Idle wrote & sings it, actually)
! See if it makes you feel as small and insignificant as Mrs. Brown…
FST10 ©GMS/GFR 2010 Milk – Consumption
! Only humans:
! ! Consume milk of other species Consume milk after weaning
! (Oh, all right, tell me about your kitty-cat) ! Northern Europeans are the primary group that:
! Consumes milk as adults become lactose intolerant decrease and lose production of LACTASE and cannot digest lactose.
FST10 ©GMS/GFR 2010 ! Many other humans:
! ! LACTOSE INTOLERANCE
! LACTOSE INTOLERANCE
! ! At least half of the world’s adults cannot effectively digest lactose ! McGee: “Ethnic chauvinism” We didn’t know about Lactose Intolerance until the 1950s-1960s UN, Peace Corps in SE Asia FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 LACTOSE INTOLERANCE
— Getting around the problem…
! Use of lactase enymes ! Directly in processing ! Naturally with fermented dairy products ! Dietary supplements (“Lact-Aid” tablets to be taken with meals) ! cf. Bean-O for beans (there will “be no” gas) FST10 ©GMS/GFR 2010 For every PhD there is an equal & opposite PhD…
! Cheese Consumption & Lactose Intolerance
Cheese Consumption, 2003 kg/person/year Lactose Intolerance Other things in dairy might cause digestion discomfort (such as proteins)
! Cheese is concentrated milk proteins and fat Lactose concentration begins at about that of milk Ripening reduces lactose concentration in cheese and yogurt. (later)
FST10 ©GMS/GFR 2010 Greece France Italy Switzerland Germany Austria Sweden 27.3 24.0 22.9 20.6 20.2 19.5 17.9
FST10 ©GMS/GFR 2010 ! ! Carbohydrate - Examples
! Carbohydrates - Starch
! Sugars A polysaccharide
! ! Starches
! a polymer of many sugar moieties (glucose) amylose: linear amylopectin: branched Composed of two polymers:
! ! FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 Starch Polymers FST10 ©GMS/GFR 2010 Simplify the Chemical Structure of Starch
Replace each of the preceding complex sugar monosaccharide structures by a circle with a “G” (for glucose) in the middle — and then just string them together…
Like we see on the next slide
FST10 ©GMS/GFR 2010 GGGGGGGG G G G G G G G G ••• G G G G G G G G Amylose Starch Granule Structure
! ! ! Swelling of Starch
Upon heating, starch granules swell (fill with water) Eventually, a sol (solution) is formed Upon cooling, a gel is formed from starch granules trapping water hilum laminations
FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 So, What’s a GEL?
! ! Q: Difference between “Regular chocolate pudding” and “Instant”
! Mostly solvent (water) entrapped in a network of polymer Examples
! Regular is smoother and has better texture
! Starch (Chocolate pudding)
! ! ! Regular must be heated to gelatinize the starch 1/4 cup Cornstarch (~59mL, ~.6g/mL) = ~35.4g 2 3/4 cup Milk (650 mL, 86% water) =~560g water ~95% water 20g Jello 946g water ~97% water
FST10 ©GMS/GFR 2010 ! ! Instant does not have as good a texture Instant just needs milk added and is then mixed
! ! ! Protein (Gelatin desserts - later)
! ! ! ! The reason it thickens without heating is that they have used pre-gelatinized starch The pre-gelatinized starch is also chemically modified to assist it dissolving and to prevent rapid retrogradation What’s retrogradation? — next slide please
FST10 ©GMS/GFR 2010 Starch — Retrogradation
! Retrogradation Inhibition or slowing
! ! The realignment of the starch polymers that causes the expulsion of water Causes the staling of bread (and other foods) The more amylopectin, the less retrogradation Starches with high amylopectin percentages are called “waxy” starches
! ! e.g., cornstarch ! To prevent retrogradation manufacturers chemically modify starches
! Must be labeled as “modified starch”
FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 Examples of Staling
! ! Examples of Staling
! ! Bread becomes tough & gritty Staling is not the formation of mold
! Mold can accompany the staling of bread, however, it is not staling per se French fries stale within minutes of deep fat frying Put gravy or pudding in a refrigerator and the next day cracks and “rivers” form ... FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 Folklore
! Bottom line…
Q. Does bread stale more quickly being left on the counter or when put in the freezer or refrigerator?
! ! Q. Does bread stale more quickly being left on the counter or when put in the freezer or refrigerator? A. Bread stales less quickly when left on the counter
! Freezing causes:
! ! ! A. Bread stales less quickly when left on the counter
! Retrogradation to proceed more quickly than leaving bread on counter due to ice crystal formation Evaporation of water ! Refrigeration causes:
! ! Bread will last longer (mold free) in the refrigerator or freezer
! Retrogradation to proceed more quickly than leaving bread on counter due to ice crystal formation Evaporation of water But it will be more stale when taken out
! You can compensate (a little) by reheating (like nuking in a microwave for a few seconds) FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 Carbohydrates - Starch
! ! Carbohydrates - Starch
! ! Amylase: enzyme(s) used to breakdown starch 2 Major types of amylases
! ! Amylase: enzyme(s) used to breakdown starch 2 Major types of amylases
! ! alpha — a random attack beta — cleaves off maltose alpha — a random attack beta — cleaves off maltose ! This is especially important to brewers
! Dr. Bamforth talks about the malting processes in brewing where starch in barley is broken down to maltose and glucose in order for yeast to ferment starch into alcohol
FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 "-amylase action on starch $-amylase action on starch FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 Dietary Fiber
American Association of Cereal Chemists’ Definition:
! Fiber provides bulk to help move material through the GI tract
Feces are 75% water, 25% solids; of the solids • 30% roughage • insoluble ﬁber: undigestible (e.g. cellulose, lignin) • - acts as a bowel irritant • - draws H2O out into lumen • - cleans out lower GI - correlated with less colon cancer • soluble ﬁber: partially digestible (e.g. gums, pectins???) • - lowers cholesterol concentration • - more cholesterol converted to bile salts • - cholesterol pulled from bloodstream • 20% dead bacteria • 10-20% fat • 10-20% inorganic material FST10 ©GMS/GFR 2010 • 10% undigested proteins ! ! Dietary fiber is the edible parts of plants or analogous carbohydrates that are resistant to digestion and absorption in the human small intestine with complete or partial fermentation in the large intestine. Includes polysaccharides, oligosaccharides, lignin, and associated plant substances. FST10 ©GMS/GFR 2010 Dietary Fiber Components
! Pectin — The Inside Skinny
! ! ! ! Cellulose (wood & paper CHO)— (starch-like, but with a different biochemical linkage; indigestible by mammals except ruminants where microorganisms actually break down the cellulose into simple glucose sugars) Hemi-celluloses (a bad term invented by somebody who will not stand up and take the blame) — a bunch of complex molecules nobody understands very well. But, a component of dietary fiber Gums & mucilages (more dietary fiber stuff); we’ll look at this right after we look at … Pectins (the first thing we will look at because it’s important in foods) — [enter stage left]… ! Pectin is what nature uses to cement plant cell walls together ! Refer to Dr. Shoemaker ’s lecture on Fruits & Vegetables !T echnically, some people call the original stuff Protopectin, but who’s counting… When plant cells are heated, they release broken “chunks” of the cell wall pectin to form smaller molecules that we call ordinary pectin
FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 Cell Wall Chloroplast Pectin — The Inside Skinny
! ! Middle lamella (Pectin glue between
cells) V a c u o l e Starch Grain ! ! So, we can just boil some fruits and release enough pectin to make a gel But we need to also have acid and sugar present to form the gel A gel with sugar is called a jelly (or jam) So, for example, we could check in with Alton and watch some snippets from his program for making wonderful jams & preserves
! ! Plasmalemma
FST10 ©GMS/GFR 2010 Watch for Alton grabbing the pineapple from the other guy’s shopping cart Oh, the quality is not too great, but it’ll do...
FST10 ©GMS/GFR 2010 Here’s some stuff that’s not pectin at all, but gels FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 Thickeners & gums
! ! ! Famous Thickeners & Gums
Polysaccharide derivatives “Natural” products Thicken and stabilize (interact with water)
! Locust bean gum
galactomannan from seeds of Carob tree !
sulfated polysaccharides extracted from red seaweeds !
linear !-D-mannuronate and C-5 epimer "-L-guluronate !
! Xanthan gum
Glucose, mannose and glucuronic acid !
FST10 ©GMS/GFR 2010
! Guar gum
galactomannan from Guar beans
FST10 ©GMS/GFR 2010 Trend in Dietary Fiber Bran - not just for Old Folks
! ! ! FST10 ©GMS/GFR 2010 Bran is the hard outer layer of grain and consists of combined aleurone and pericarp. Along with germ, it is an integral part of whole grains. Pericarp contains fiber Also, the name of Vlad the Impaler’s castle FST10 ©GMS/GFR 2010 Fiber Stimulates the Bowel Would you like to see some review questions?
OK, let’s look a few terms back… FST10 ©GMS/GFR 2010 Phil Hartman, SNL, NBC FST10 ©GMS/GFR 2010 40) Which of the following is/are not polymers?
! ! ! ! ! 42) Bread kept in the fridge will quickly
! ! ! ! ! a) b) c) d) e) amylose polysaccharides amylopectin xylitol dextrin a) b) c) d) e) Mold Gelatinize Undergo birefringence Retrograde Form a sol FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 43) How are starch and cellulose similar?
! ! ! ! ! 1) Dietary fiber is digestible.
! ! a) b) c) d) e) Both are digestible to humans Both are indigestible to humans Both have branched structures Sugar linkages are the same Both are made from glucose moieties a) True b) False FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 2) Cellulose is composed of many _____ molecules.
! ! ! ! ! 5) Which is not considered a component of dietary fiber?
! ! ! ! ! a) Lactose b) Glucose c) Galactose d) Maltose e) Sucrose a) Cellulose b) Hemicellulose c) Amylopectin d) Pectin e) Maltodextrins FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 6) Which is not digestible?
! ! ! ! ! 60) A polysaccharide consisting of “animal starch” (P. 588 old)
! ! ! ! ! a) Amylose b) Starch c) Protein d) Pectin e) Amylopectin a) b) c) d) e) Cellulose Pectin Glycogen Hemicellulose Amylose FST10 ©GMS/GFR 2010 FST10 ©GMS/GFR 2010 Starch, Pectins, Dietary Fiber 終…
FST10 ©GMS/GFR 2010 ...
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This note was uploaded on 03/01/2011 for the course FST 10 taught by Professor Jack during the Fall '08 term at UC Davis.
- Fall '08