4 Polymorph Conversion

Question 1

what are the methods for converting beta to beta-prime?

Answer 1

• interesterification
• interesterification & hydrogenation
• winterization (destearinization)
• addition of cottonseed oil/tallow flakes (beta-prime)

Question 2

what is intEResterification?

Answer 2

exchange of acyl groups on the glycerol backbone between triglycerides w/a catalyst (eg Sn, Pb, Zn, alkali earth metals)

1,2,3 –> 2,3,1

Question 3

what’s the purpose of interesterification?

Answer 3

• randomize FA distribution to change properties without forming trans FAs
• removes graininess in lard
• enzyme catalyzed can make mono/diglycerides used as emulsifiers

Question 4

how is interesterification carried out?

Answer 4

• under low temps

- more saturated long chain FAs will fractionally crystallize out

Question 5

what is the process in which fats are interesterified to result in random distribution of FAs called?

Answer 5

randomization

Question 6

what catalyst should be used to create a FA with a SPECIFIC composition when doing interesterification?

Answer 6

enzyme (lipase)

Question 7

how can human milk structure be replicated artificially?

Answer 7

interesterification using sn-1,3 specific lipase

Question 8

what is intRAesterification?

Answer 8

• acyl groups transferred WITHIN triglycerides

- can change the FAs present on an individual TG

Question 9

what catalysts are used for low/high temp interesterification?

Answer 9

low: KOH, NaOH
high: NaOCH3 (sodium methanoxide)

Question 10

what are the steps of the interesterification mechanism?

Answer 10

1) formation of enolate ion
2) formation of beta-keto ester
3) interesterification

Question 11

how is randomized interesterification achieved?

Answer 11

rxn is carried out to an equilibrium condition

Question 12

how is directed interesterification achieved?

Answer 12

fat must be crystallized during the reactions. trisaturated glycerides crystallize first

Question 13

what are the products of interesterification of lard called?

Answer 13

• CML: crystal-modified lard (intRAmolecular)
• PML: partially modified lard (random dist)
• DIL: direct interesterified lard (directed)

Question 14

what properties of oils can be altered through changing polymorphs?

Answer 14

• air incorporation
• plasticity
• consistency
• solid-liquid ratio

Question 15

what’s the air incorporation and consistency of BETA PRIME polymorphs like?

Answer 15

• lots of small bubbles

- smooth

Question 16

what’s the air incorporation and consistency of BETA polymorphs like?

Answer 16

• large air bubbles

- grainy/waxy

Question 17

which polymorph is most preferred in baking?

Answer 17

beta prime

• most small air bubbles = largest volume & consistency
• promotes tenderness

Question 18

what’s responsible for “cocoa bloom?”

Answer 18

the conversion of beta-prime FAs to beta FAs

Question 19

what is tempering?

Answer 19

transformation of FAs to a desired polymorph. accomplished through meticulously controlling temperature during melting/cooling

Question 20

does randomization improve or worsen the plastic range of lard?

Answer 20

improve

Question 21

define plasticity

Answer 21

changes in consistency as a function of temperature

Question 22

define consistency

Answer 22

apparent hardness at a temperature

Question 23

how is it possible that we can make margarine high in PUFAs and free of trans fats?

Answer 23

interesterifying a blend of liquid oil and completely hydrogenated oil

Question 24

what commodities are of greatest interest to a food science when working with fats?

Answer 24

• shortening
• margarine
• confectionery fat

Question 25

what do shortenings do?

Answer 25

- reduce elasticity of dough (cuts gluten) | - increases flakiness

Question 26

shortening power increases as degree of unsaturation:

Answer 26

increases

Question 27

does hydrogenated veggie oil or lard make better shortening?

Answer 27

functionally, they're about the same. however, lard is grainier but this can be fixed with interesterification

Question 28

what can margarines be made of?

Answer 28

- hydrogenated fats - mixture of hydrogenated fats & unhydrogenated oils - mixture of interesterified fats & unhydrogenated oils - mixture of unhydrogenated fats

Question 29

what are the 3 most stable margarine blends?

Answer 29

1) 75% co-randomized (40% coconut oil, 60% palm oil) 2) 10% co-randomized (50% coconut, 50% hydrogenated canola oil) 3) 15% hydrogenated soybean oil

Question 30

how is margarine made?

Answer 30

- mixture is plopped into a SSHE which partially solidifies the material - mixture is then tempered for optimal plasticity/spreadability

Question 31

what must be done during tempering to avoid melting and a later conversion to beta crystals?

Answer 31

removal of heat of transformation

Question 32

what's the TG composition of the cocoa butter?

Answer 32

- 20% SOS - 50% POS - 5% POP ``` s = stearic o = oleic p = palmitic ```

Question 33

cocoa butter has a (narrow/wide) melting point range

Answer 33

narrow

Question 34

randomizing palm kernel oil does what to its melting point and texture?

Answer 34

- decreases melting point (from 46°C to 35°C) | - less waxy