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Professor Dr. Jin Bangquan Deparment. of Food Science & Nutrition NJNU

Protien Nutrition. Professor Dr. Jin Bangquan Deparment. of Food Science & Nutrition NJNU. Review: Protein Metabolism. Review: Protein Chemical Function. 氨基酸缩合. 亚基形成. 肽链延长. 蛋白质. §1 Concept. Definition: Protein is the life base Complex of 20 Amino Acids (AA) in body Named:

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Professor Dr. Jin Bangquan Deparment. of Food Science & Nutrition NJNU

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  1. Protien Nutrition Professor Dr. Jin Bangquan Deparment. of Food Science & Nutrition NJNU

  2. Review:Protein Metabolism

  3. Review:Protein Chemical Function

  4. 氨基酸缩合 亚基形成 肽链延长 蛋白质

  5. §1 Concept • Definition: Protein is the life base Complex of 20 Amino Acids (AA) in body • Named: 1836 Chemist Muldgr (柏采里.乌斯 Sweden) found 1888 Berzelius named 1852-1919 Emil Fischer (Germany) ，建立有机结构 化学和蛋白质分析法，1902年获诺贝尔化学奖, 1907 年合成18个AA的肽链。

  6. Composition • Main Elements: C, H, O, N • Fewer Others: S, Fe, Cu---- • Content in Body: 16-19% • Renew:3% in a day (20g Prot. or 3.2g N) • Exchange : 1/4 in total Surviving 30-50d when starving

  7. Analysis Method (GB) • kjeldehl • CP% = N×6.25

  8. §2 Protein function & classification 1 Function • Composition in Body: Muscle, Blood plasma • Physiological Actives: Enzyme keeping osmosis • Supplying Energy: 1g = 4kcal/g = 16.7kJ/g

  9. 2 Classification • 按EAA： 完全蛋白 半完全蛋白 不完全蛋白 • 按结构和溶解度： 简单蛋白 硬蛋白 结合蛋白

  10. *Protein classification in Nutrition N: 根据食物蛋白质所含氨基酸的种类和数量 将食物蛋白质分三类： 1. 完全蛋白质   这是一类优质蛋白质。它们所含的必需氨基酸种类齐全，数量充足，彼此比例适当。这一类蛋白质不但可以维持人体健康，还可以促进生长发育。奶、蛋、鱼、肉中的蛋白质都属于完全蛋白质。 2. 半完全蛋白质 这类蛋白质所含氨基酸虽然种类齐全，但其中某些氨基酸的数量不能满足人体的需要。它们可以维持生命，但不能促进生长发育。例如，小麦中的麦胶蛋白便是半完全蛋白质，含赖氨酸很少。食物中所含与人体所需相比有差距的某一种或某几种氨基酸叫做限制氨基酸。谷类蛋白质中赖氨酸含量多半较少，所以，它们的限制氨基酸是赖氨酸。 3. 不完全蛋白质   这类蛋白质不能提供人体所需的全部必需氨基酸，单纯靠它们既不能促进生长发育，也不能维持生命。例如，肉皮中的胶原蛋白便是不完全蛋白质。

  11. 4 Reference Protein Egg Human milk These AA pattern are similar to human AAP

  12. §3 Amino Acid (AA) & Peptide Definition • AA is the basic unit for synthesizing protein α-AA chain • Peptide can carry on the protein function

  13. Classification 1According toα-AA chain -NH3+, -COO- Neutral Alkali Acid Suppl.

  14. Classification 2According to Nutritional important • Essential Amino Acid (EAA) • Limiting Amino Acid (LAA) • Non-Essential Amino Acid (NEAA)

  15. Essential Amino Acid (EAA):(8+1) Leucine (Leu, 1st 1810) Isoleucine (Ile) Lysine (Lys) Methionine (Met) Phenylalanine (Phe) Threonine (Thr, last1935) Trypotophane (Try) Valine (Val) Histidine (His for Infant) Knownas 1983 We need them from Food, but not made in ourselves

  16. Limiting Amino Acid (LAA) • Three:Lys, Met, Thr Special for Growing • Ideal Ratio:Lys: Met: Thr = 100: 60: 40 inRation • Amino Acid Pattern：Compared with different kinds, ratio & content between human body and food supplement Trp as 1 • High quality of protein:

  17. Nonessential Amino Acid (NEAA) NEAAcan be synthesized from others in body Ala Arg Asp Asn Glu Gln Gly Pro Ser Conditional EAA Cys Tyr When Cys and Tyr were enough in body the requirement of Met and Phe was decreased by 30% and 50% .

  18. Amino Acid Pattern (AAP) Complementary Action of Protein/Amino Acids can be access tobody protein pattern from various foodstuffs Such as : beef/ Pork + Corn/ Rice Bio-value Lys Met + Cys 1The amino acid values for the pattern are expressed on a per-gram-of-nitrogen basis 2The amino acid patterns and the total nitrogen content were used to calculate the levels of individual amino acids per 100 g of food

  19. Examples: Kinds Corn Flour Soya Account （%） 21 31 48 100 Lys/Met Lys Lys Met Lys Met BV(%) 60 67 64 70 Kinds Flour Millet SoyaBeef Account （%） 39 13 22 26 100 BV(%) 67 57 64 69 89

  20. §4Nitrogen Balance & Balanced Diet • Balanced Diet • Nitrogen Balance Suppl.

  21. 1 Balanced Diet Hypothesis of Ideal Protein • The number of EAA is enough • The ratio of AA is suitable from foodstuffs • Various foodsources A set of values that serve as the pattern for calculating the amino acid profile of other similar foods

  22. 2 Nitrogen Balance • Definition: N-intake is equal to N-ejection every day keeping weight for adults • Index NB= N-intake - N-ejection (Urine + Feces + Skin) • Zero Nitrogen Balance： N-intake = N-ejection • Positive Nitrogen Balance： N-intake > N-ejection • Negative Nitrogen Balance：N-intake < N-ejection Notes: ONL≈3.2g/d (×6.25) Protein Loss≈20g/d (= 16%×N) Obligatory Nitrogen Loss/ ONL/必要的氮损失

  23. §5 Nutritional Evaluation for Foods1 • CP or AA content (Ratio of EAA : CP) • CP Digestibility 1 Apparent Digestibility: (Protein in food - Protein in feces ) ÷ Protein in food × 100% 2 True Digestibility*: (Protein in food - Protein in Control) ÷ Protein in food × 100% P14-16

  24. Nutritional Evaluation for Foods2 • Nutritional Absorptivity : Percentage of Nutrients in Gut • Biological Value (BV)* BV=Food N-(FN+UN)/ Food N-FN100% • Net Protein Utilization (NPU) NPU= Digestibility BV= UN-EnN/Food N100

  25. Protein Availability or Efficiency • Percentage of change and synthesis into new tissue Body Weight Gain÷ Protein in food × 100% Body Weight Gain÷ a kind of food × 100% Data tested from animal , no human P16 top

  26. §5 P-requirement & Supplement1 • Basic requirement: 30g CP/d for adult • Safety Supplement: 0.8g/kg.d (48-56g/d) • Recommendation: 1.16g/kg.d (70-90g/d) RDA: 72g/d • CP in Energy: 10-12% (P: E) for adult 12-14% for child range: 10-20% (15-20) P18

  27. P-Supplement 2 From foods at all • Food Protein Source 1 Protein content >15% eg: meat, egg, soybean 2 Better Protein Source eg: as above

  28. Sources and Content in foods • Grain： 8-14% • Beans：Soybean 35-40% Other bean 12-25% • Meat, Egg, Fish, Poultry：10-20% • Milk：3-5% High quality protein: Meat, Egg, Fish Poultry, Milk, Soybean Suppl. Ratio in diet：40-50% Protein in Energy：15-20%

  29. Malnutrition P17-18 • Low-protein in blood (albumin 35-50g/L) • Dropsy • Marasmus Examples in Nutritional Evaluation & Anthropometry P197-205

  30. Deficiency or Surplus • Deficiency： Dropsy & Marasmus • Surplus：Over acid in body Accumulating NH4 + , Cr Overload of liver & kidney

  31. Protein Evaluation for Human • Arm Circle • Albumin in serum • Urine、Cr、BUN

  32. Question 1 What is protein？ 2 Water is referent protein? 3 Which food is the source of better protein？ 4 What and how many are EAA ？ 5 What is LAA？Why？ 6 What is AA pattern？ 7 How to increase bio-value of food protein？ 8 What is N-balance Hypothesis？ 9 Which effects are on protein utilization？ 10 What is protein support problem？

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