Technical Challenges (3) Flashcards
what does “dietary fibers” include?
polymeric CHOS: cellulose, hemicellulose, pectin, gum
what are characteristics that fibers affect?
- color and flavor
- oil and H2O retention
- colloidal emulsion stability (improves)
- texture and gel formation
- other viscometric properties (eg. thickening and mouthfeel)
what are functions of cellulose in food formulations?
- stabilize foams and emulsions
- stabilize pectin and starch gels under heating
- modify textures
- improve adhesion
- replace fat and oil
- control ice crystal growth
what does cellulose not affect?
flavor
color
microbial contamination
describe the function of native cellulose powders in food pdts
- does not soften on hydration and heating
- may impart rough mouthfeel
describe benefits of using native cellulose in food pdts
- abundant
- cost effective
- inert and insoluble
- no caloric value
describe the production of colloidal MMC
- fibrous cellulose material is hydrolyzed to remove the paracrystalline region to form MCC
- add hydrocolloids (substance that forms gel in water) and CMC (carboxyl methyl cellulose) to form colloidal MMC
what is MMC
microcrystalline cellulose
describe the functional properties of MCC
- foam stabilizer
- emulsion stabilier
- heat stability w/ minimal loss of viscosity
- textural modifier (shortens texture or adds body)
- suspension aid of particulates
- replace fats and oils in emulsions
- controls ice crystal growth
- prevents aggregation of protein and other solids
- opacifier and whitening
what properties of starch is improved with the addition of MCC?
- improvement of heat and shear stability
- less starch thickener needed
what is CMC
carboxymethylcellulose
how is CMC chemically formed?
cellulose + alkali + chloroacetic acid = CMC
what requirement is needed for CMC to be water soluble?
degree of substitution of 0.45 or higher
in CMC, higher degree of polymerization = ____ (higher/lower) viscosity
higher
what differs chemically between different CMC?
- degrees of polymerization
- degrees of substitution
- uniformity of carboxyl methyl groups
describe solubility of CMC
soluble in cold water
- gives clear solutions w/ neutral flavor
what is the primary property of CMC?
what is it commonly used for?
- viscosity production
- used as a thickener and stabilizer
what are functional properties of CMC
- soluble in cold water
- increases viscosity
- stabilizer (b/d of anionic nature)
- improves water retention and water binding
- improves moistness and prolongs shelf life
- good film forming properties
what is HPMC
hydroxypropyl methyl cellulose
what structural/chemical components is HPMC characterized by?
- monomeric chain length
- degree of substitution
- ratios of hydroxypropyl and methyl substitution
MC and HPMC are soluble in ___ water but not in ___ water
cold; hot
what are major functional properties of HPMC?
- high emulsion stability
- extremely soluble in water
- good water retention
- reversible thermal gelation
- good resistance in acidic medium
- good film forming properties
describe the unique reversible thermal gelation property of HPMC
viscosity initially decreases with rising temp but then increases until a gel is formed
processes are reversible
describe solubility of HPC
water soluble (up to 40C) and organic soluble
why is HPC used in oil-in-water emulsions and whipped products?
- it is a good surface active agent (due to low surface and interfacial tension in solution)
- it has a good protective colloid action
how is bacterial or microfibrous cellulose produced?
by microbial fermentation of Acetobacter xylinum
how is bacterial cellulose similar or different than plant cellulose?
chemically identical, but has smaller fibers bundled to form a 3D network which allows higher surface area to provide high stability to temp, pH, salts, oxidizers, shear
what can be combined with bacterial cellulose to promote higher dispersion of a food pdt?
co-agents such as sucrose and CMC
how do pectins form gels?
in presence of water, acid and sugar
what are health benefits of pectin?
- lower cholesterol
- lower serum glucose
- anti-cancer activities
what can pectins be classified as?
- high/low ester pectins
2. high/low methoxy pectins
what are applications of pectin?
- thickening and gelling agents
- stabilizer in candies, syrups, frozen desserts, jams, jellies
what factors determine gelling properties of pectins?
- temp
- pectin type
- DE (degree of esterification)
- DA( degree of acetylation)
- pH
- sugar
- calcium
with pectins, higher degree of methyl substitution of the sugar acid = ____ (higher/lower) temp of gelation
higher
what requirements are needed for high methoxyl pectins to form gels?
- high soluble solids contents (>55%)
- low pH (2.7-3.5)
with pectins, higher DE = ____ (higher/lower) soluble solids required = (higher/lower) pH value at which gels can form
higher DE = LOWER amount of soluble solids required = HIGHER pH at which gels form
how does the addition of divalent cations (Ca) affect the gel formation of low-methoxyl pectins?
forms gels at lower soluble solids and higher pH
how does acetylation affect gel formation of pectins?
prevents gel formation but increases stabilizing and emulsifying effects of pectin
how can you modify functionalities of pectins?
using pectinolytic enzymes
example: to create amidated pectin
what is amidated pectin? how do they behave? what are characteristics?
a modified form of pectin
behaves like low-ester pectins
characteristics:
- more tolerant of varying Ca concentrations
- modifies hydrophilic nature of pectin to obtain a more compatible hydrocolloid
- increases water holding capacity
how is sugar beet pectin used? what can it substitute?
used for flavor oil emulsions due to its emulsifying effects
can substitute gum arabic in emulsions
