식품 ≫ 단백질 ≫ 채내 역할

단백질 구조의 변형 : 효소, 물리적, 화학적

단백질 구조 : 단백 결합
- 단백질 folding
- 단백질 Unfolding
- 구조 변화(변성) 원인
- 응집, Aggregation

Some proteins don’t exhibit good functional properties and must be modified.
Other proteins are excellent in one functional aspect but poor in another but can be modified to have a broader range of function.

1. Chemical modification
Reactive amino acids are chemically modified by adding a group to them.
- Lysine, tyrosine and cysteine
- Increases solubility and gel-forming abilities.
- Modified protein has to be non-toxic and digestible
Retain 50-100% of original biological value
Often used in very small amounts due to possible toxicity

 

2. Enzymatic modification

Protein hydrolysis (proteolytic enzymes)
- Proteins broken down by enzymes to smaller peptides
- Improved solubility and biological value

Protein cross-linking
- Some enzymes (transglutaminase) can covalently link proteins together
- Great improvement in gel strength

3. Physical modification
Most of the methods involve heat to partly denature the proteins; alkaline treatment

Texturized vegetable proteins – TVP (e.g. soy meat)
- A combination of heat (above 60C), pressure, high pH (11) and ionic strength used to solubilize and denature the proteins which rearrange into 3D gel structures with meat like texture
- Good water and fat holding capacity
- Cheaper than muscle proteins - often used in meat products

Protein based fat substitutes (e.g. SimplesseTM )
- Milk or egg proteins heat denatured and mechanically sheared: on cooling they form small globular particles that have the same mouthfeel and juiciness as fat.
- SimplesseTM is very sensitive to high heat – limits its use in processing