PECTINS

sheet/spoon test

cool metal spoon dipped into boiling jelly, raise from mixture and tip spoon, drops fall off spoon as a sheet when jelly is done

deficient in pectin and acid

peaches

overripe?

pectin is degraded

what is a high-methoxy gel made of?

pectin, water, sugar, and acid

deficient in acid but adequate pectin

sweet apples, unripe bananas, unripe figs, unripe pears

low methoxy pectins

< 1/2 of COOH are satisfied, doesn't need sugar at all, not a lot of acid groups

pectin of a high-methoxy gel

.5-1 %, degree of esterification

high methoxy group pectins

1/2 to 3/4 of COOH are esterfied

boiling temp of jelly?

103-105 degrees or 4.4 above the boiling point of the water?

what is pectin made of?

a linear polymer of approximately 300 to 1000 galaturonic acid units

what is gel?

an interlacing network of collodially dispersed linear molecules bound together by intermolecular force that entraps water and solutes

adequate acid but deficient in pectin

apricots, strawberries

sugar of a high-methoxy gel

dehydrates pectin, tenderizes, keeps water in syrup, preservative effect, 40-70% sugar needed, solution boils between 103-105 degrees C

ph too high?

difficult time for gel to set

water of a high-methoxy gel

disperses pectin sugar and acid

what do low methoxy pectins do?

forms a gel with salt linkage, stearic fit requires linearity, requires divalent cations, if you add calcium these pectins form cross-linkages, doesn't need sugar to gel

ph too low?

gel start forming in pan

acids of a high-methoxy gel

gels form between 2.8-3.4 ph (no more than 3.5), most at home recipes ph 3.2 with 65% sugar, acid neutralizes charge on pectin so molecules can approach each other

pectin functions?

high and low sugar jams, heat resistant food spreads, fruit preparations for yogurt, glazings, milk puddings, instant creams, fat replacer, jelly beans, cereal bars (binding pectin)

adequate acid and pectin

lemon, grapes, sour plums, gooseberries, raspberries, currants, logan berries, cranberries, tart apples, blackberries, crabapples

too much pectin?

not a gel former

undercooked?

the pectin hasn't been concentrated so it might not gel which could lead to crystals

underripe?

too much protopectin, no gels formed

high methoxy pectin jells

used in jellies and jams, gels with hydrogen bonding, requires a low ph (3.5), requires sugar to dehydrate pectin, linear

low methoxy pectin gels

used in low sugar jellies, ge;s with salt linkage, stearic fit requires linearity, requires divalent cations, if you add calcium these pectins form cross-linkages, doesn't need sugar to gel

protopectins

water insoluble, very long chain, do not gel

pectic acids

water soluble no methyl groups

pectins (pectinic acids)

water soluble, used for jellies