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 ( 표 16.1)

– 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

kcal/g 3.74kJ 4.184

1kcalgram

kJ 15.6180gmole 1

molekJ 2816

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– lactose 의 가수분해로

생성

O

H

HO

H

HO

H

OH

OHHH

OH

CH2

HCH2

H OH

HO H

O

H

OH

HO

O

OH

H

H

HO

H

OH

OHHH

OH

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 ( 표 16.2)

– 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 g 을 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

Triglyceride

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

Lipidproteins

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

H

Li

Rb

Na

K

Cs

Fr

Be

Sr

Mg

Ca

Ba

Ra

Ga

B

Al

In

Tl

Ge

C

Si

Sn

Pb

As

N

P

Sb

Bi

Se

O

S

Te

Po

Br

F

Cl

I

At

Kr

Ne

Ar

Xe

Rn

He

Y

Sc

Lu

Lr

Zr

Ti

Hf

Rf

Nb

V

Ta

Ha

Mo

Cr

W

Sg

Tc

Mn

Re

Ns

Ru

Fe

Os

Hs

Rh

Co

Ir

Mt

Pd

Ni

Pt

110

Ag

Cu

Au

111

Cd

Zn

Hg

112

Principal Components

Major Minerals Trace Minerals

Homework• 교과서 496 쪽 연습문제

– 6, 9, 16

References• http://www.americanscientist.org/articles/

99articles/Hardison.html

• http://www.people.virginia.edu/~rjh9u/hemoglob.html

• http://www.equal.com/

• http://www.aspartame.org/

• http://www.chosun.ac.kr/~mjkoh/a338.html