Chemistry of Food 식품화학

Chapter 16

Chemistry of Food

식품화학

What the body needs!

• 영양소 Nutrients

– substances that are needed by our bodies

• What do are bodies need?

– 물 water

– 탄수화물 carbohydrates

– 지방 (지질) lipids (fats)

– 비타민 vitamins

– 무기질 minerals 

Water

• Water

– 가장 간단하고 생명유지에 최소한의 양 필요

– 몸의 65-75% (approx. 40 liters)

• 물의 역할

– solvent -  polar OH, NH group 

(탄수화물, 단백질, 수용성 비타민)

– key transport system in body

• 삼투

– 세포 안과 밖으로 물이 출입하는 방법

Water

• 일반 음식물의 물 함유량 (표16.1)

– 맥주 90%

– 사과 84%

– 감자 76%

– 힌빵 39%

Carbohydrates

• 탄수화물

– Compounds composed of carbon hydrogen and oxygen, with a H/O ratio of 2 to 1

– Name comes from carbon, C, and hydrate, H2O

– Cx(H2O)y – most common C6H12O6

• Three classes of carbohydrate

– 간단한 당(단당류와 이당류)

– 녹말 (고분자 탄수화물)

– 섬유질

Carbohydrates

• Energy of Carbohydrates

– glucose is the primary energy source

– C6H12O6 + 6 O2    6 CO2 + 6 H2O + 2816kJ/mol

• Calories 

– dietary calories = kcal

1 kcal = 4.184kJ

Carbohydrates

• Carbohydrate are made from sugars

– natural polymer

• A single sugar is called monosaccharide

– 3 common monosaccharide

– glucose, galactose, fructose

– all have the same formula, C6H12O6

– different structures

Monosaccharides

• Glucose

– 혈액 속의 당

– 혈당, 포도당

• Fructose

– 꿀과 과일 속의 당

– 과당

• Galactose

– 자연식품에는 존재무

– lactose의 가수분해로 생성

Disaccharides

• 이당류는 두 개의 단당류가 축합 반응

– 2 C6H12O6  C12H22O11  +  H2O

• Common disaccharides

– sucrose

• glucose and fructose

• 당(sugar) - 설탕

– lactose

• glucose and galactose

• 포유류의 젖에 들어 있는 당 (젖당)

– maltose

• glucose and glucose

• startch 가수분해로 생성

Glycosidic bond

• 글리코시드 결합

– 두 개의 단당류를 결합

– 물이 빠져 나오는 축합 반응

Sweetener

• 상대적인 당도 (표16.2)

– lactose 0.2

– sucrose (sugar) 1.0

– fructose 1.7

– xylitol 2.0

– aspartame (L-aspartyl-L-phenylalanine methyl ester, 고온분해) 200

– saccharin (사용금지) 500

– monellin 2500

– P-4000 (사용금지) 4000

Sweetener

• 종류

– 탄수화물 계- sucrose, fructose

– 아미노산 계-monellin, aspartame

– 당 알코올 계-xylitol, sorbitol

– 합성 감미료-saccharin, P-4000

Sweetener

• 단 맛을 측정하는 방법

– 온도, 환경 고려

– 관능검사 (sensory evaluation)

• 이점 비교법 paired comparison method

• 일정한 부피의 물에 설탕 100 g을 녹이고 이것을 사카린 1 g, 0.1 g, 0.01 g 등을 녹인 용액과 맛을 보아서 비교

• 비슷한 단맛을 가진 범위가 정해지면 더 세분화해서 용액을 만들고 다시 맛을 보아서 비교

• 통계 처리 - 유의적 차이가 나지 않는 농도 범위

Complex Carbohydrates

• Complex Carbohydrates

– starch and cellulose

• 신문을 읽으며 옥수수를 먹는다

– polymers of glucose

Two Form of Glucose

Complex Carbohydrates

• Starch

– energy storage for quick release

– amylose and amylopectin 

– can be found in seed and tubers

Starch from -glucose

• Amylose 

–  1,4 glycosidic bond

– long chain of -glucose 

– that coils into a helix 

– natural organic polymer

• amylopectin

– mostly amylose 

–  1,6 glycosidic bond

– 분말형태

Complex Carbohydrates

• Cellulose

– long chains of -glucose

– not digestible

– makes up the fiber in our diet

• 섬유질 - 음식물 속의 셀룰로오스

• 섬유질 결핍은 암 발생 위험도 증가

– cleans digestive tract and carries away toxins

– found in the walls of plants

-glucose for cellulose

Fats, Oils and Lipids

• 지질, Lipids

– biological compounds that do not dissolve in water

– 지방 fats 과 기름 oils

• 몸 안에서의 역할

– 오랫동안 저장될 수 있는 에너지원 

• 불용성이므로 물에 씻겨 나가지 않음

– 동물의 피부 밑에서 추위 차단

– 세포막의 구성 성분

Fats, Oils and Lipids

• 지방과 기름

– belong to a class of compounds called triglycerides

– found in animals (fats) and plants (oils)

– solid fat, liquid oil

• 삼중글리세리드 Triglycerides

– from four molecules

– three fatty acids and a glycerol

– diglycerides and monoglycerides

Fats, Oils and Lipids

• 지방산 Fatty Acids

– Long hydrocarbon chains with a carboxylic acid group at one end, 8-22 carbon long

– even number of carbon atoms

– Can have one or more double bonds

• 포화 Saturation 

– 포화 – fatty acids with no double bonds

– 불포화 – one or more double bonds

– 다중 불포화 – two or more double bonds

Fats, Oils and Lipids

• Saturation

– saturation has become an important health issue

– saturated fats are more easily converted to cholesterol, which is linked to heart disease

– cholesterol is only produced by mammals 

• Cholesterol (C27H46O)

– water insoluble lipid

– dissolved in other water soluble media 

– building block for vitamins and hormones

– only animals (in meat, milk, egg)

Lipoprotein

• 지방 단백질

– 지질 (지방과 콜레스테롤) + 단백질

– 지질을 물에 녹을 수 있게 해 준다

– 지질이 많을수록 밀도 감소

– Very low density lipoprotein

– low density lipoprotein - 나쁜 콜레스테롤

– high density lipoprotein - 좋은 콜레스테롤

Proteins

• Proteins

– water soluble

– polymers of 20 amino acids with peptide bonds 

– complex and highly specific structure

– meat, egg, milk, bean, nuts, rice - cereal

• Role of Proteins

– tissue (muscles and organs)

– enzymes

– biological functions (immune system)

Proteins

• Proteins

– proteins must be broken down before digestion

– cooking denatures the proteins, which assist in digestion

– digestion requires acidic condition and enzymes break down protein to amino acids

• Dietary Essential Amino Acids

– bodies can produce 11 of 20 amino acids

– essential amino acids are those we can not produce (egg white and meat contains all)

Protein Structure

• Primary structure

– 아미노산의 종류와 결합 순서

– 펩타이드 결합

• Secondary structure

– 나선 혹은 판

– 수소 결합

• Tertiary structure

– 이차 구조가 다시 접혀 이루는 구조

– disulfide linkage from -SH

Protein tertiary structure

Vitamins and Minerals

• Vitamins

– 건강을 위해 꼭 필요한 화합물이나 몸에서 만들어 지지 않는 것

– required for many biological functions

• Vitamin C (retinol)

– 생식, 성장, 세포분화, 시각. 괴혈병 Scurvy

– 하루 200-500 mg

• Vitamin D (calciperol)

– 햇빛 비타민.

– 뼈와 치아 성장. 구류병 Rickets

Vitamins and Minerals

• 무기질

– 무기물과 관련된 원소

– 건강 유지에 필요

• 대표적 무기질

– Iron(Fe) – oxygen transport in the blood

– Sodium(Na) – blood serum (ions in blood)

– Calcium(Ca) – bones, blood clotting, nerve signals

– Phosphorus(P) – bones, DNA & RNA, ATP

Red blood cell & Hemoglobin

Hemoglobin

Hemoglobin

• Structural comparisons 

– Phycocyanin

• a protein found in cyanobacteria that binds a compound related to heme

• shows no significant sequence matches to modern hemoglobins. 

• However, the 3D pattern of helices is similar to the fold found in hemoglobins

– Bacterial hemoglobin (from Vitreoscilla) and a mammalian myoglobin show very similar myoglobin folds 

Necessary Elements