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Biosynthesis and Secretion of Milk Protein
applications. Moreover, xanthan gum displays an intense synergistic viscosity interactIOn with galactomannans. CURDLAN: A GEL-FORMING f3-1, 3-GLUCAN Tokuya Harada The Institute of Scientific and Industrial Research Osaka University, Japan Curdlan is a f3-g1ucan composed mainly of (1-+ 3)-f3-g1ucosidic linkages. Curdlan is produced by Alcaligenes faecalis var. myxogenes and some strains of Agrobacterium radiobacter. It has an ordered conformation at low concentrations of sodium hydroxide, whereas it almost behaves as a random coil above .22 N NaOH since optical rotation, viscositv and the extinction angle of alkaline solution of curdlan change greatly. A 2% aqueous suspension becomes clear at about 54°C and forms a gel at higher temperatures, gradually becommg cloudy. When heated to about 160°C, the gel deswells and melts. On cooling the gel to about 40°C after raising the temperature to about 60°C, the gel becomes cloudy and a low-set gel is obtained. A firm, high-set gel is obtained by raising the temperature to about 70-100°C. One may select conditions to minimize syneresis of the gel. The supramolecular structures of curdlan prepared after heating at 60°C, 90°C and 120°C respectively, with and without treatment of ultrasonication, were observed by electron microscopy using a negative staining method. Curdlan is intermediate in character between the brittleness of agar gel and the elasticity of gelatin. It has potential in food production as film, fiber, support for immobilizing enzymes and a binding agent in tobacco products. Curdlan has been shown by members of the National Cancer Centre Research Institute in Tokyo to possess marked antitumor activity against certain allogeneic tumors, particularly Sarcoma-ISO in mice.
curring cellulose and chitin, characteristic of plants and invertebrate animals. Energy would never be the only cost, however, and could not. therefore, serve as a completely satisfactory currency but it could be the base on which a monetary currency rests (rather as gold was in the past). POL YSACCHARIDES AND HEALTH I. MacDonald De!-'artment of Physiology Guy's Hospital Medical School, London The polysaccharides in the diet can, for convenience, be subdivided into those that are non-digestible and those which are to be broken down by the gut enzymes into monosaccharides and thus absorbed into the blood. The non-digestible polysaccharides have received considerable prominence recently due to the speculation that their absence from the diet is the cause of many of the diseases peculiar to the Western World. Evidence for this is rather limited. The digestible polysaccharides are useful adjuncts to the diet as they provide bulk, are cheap sources of energy and lack the osmotic properties of the constituent monosaccharide, glucose. Polysaccharides are accused of causing excess depositions of body fat. Not all carbohydrates may be equal in this respect and may, in children in the tropics, lead to a type of malnutrition. There is evidence that polysaccharides have different effects from sucrose and glucose on lipid metabolism in the body. The skin lipids are also affected by the type of carbohydrate eaten.
A SUMMARY OF THE INTERNATIONAL DAIRY FEDERAnON SYMPOSIUM Shuryo Nakai Professor Department of Food Science University of British Columbia Vancouver, B.C. V6T 1W5
SOME ASPECTS OF FOOD LEGISLATION WITH PARTICULAR REFERENCE TO STABILIZERS AND THICKENERS A.Overeem Hercules Europe S.A.. The Hague, Netherlands The author discussed the following topics: 1. The position of additives in the food acts of some European countries. 2. Codex Alimentarius criteria and lists of approved additives. 3. E.E.C. lists of approved additives. 4. The E.E.C. Directive of Emulsifiers, Stabilizers, Thickeners and Gelling Agents. 5. Adaptation of national legislation of the member states to this Directive. 6. How to obtain approval for a new polysaccharide in food. SESSION 6. SOCIAL AND NUTRITIONAL ASPECTS POLYSACCHARIDES-THE WORLD'S ENERGY CURRENCY RESERVE C.R.W. Spedding Department of Agriculture and Horticulture University of Reading Money is an energetically efficient currency, requiring the minimum expenditure of energy in the exchange of goods. However, it is possible that future values can be more soundly based on the recognition that energy supplies will become scarcer and more expensive. Energy differs from all other resources in that every human activity involves it-including the search for more of it. Short of a technical break-through in the energy cost of obtaining energy. supplies are bound to increase greatly in cost and this may dominate all other costs. This suggests that there will be greater emphasis on the use of solar radiation but this also involves materials which in turn cost energy. Thus, future calculations might best (or additionally) be made in energy. as a kind of currency rather than monetary terms. partly because they will then be more likely to reflect future monetary values. A major aim must be to live within our solar energy income, rather than on capitaL but agricultural systems have been developing in the opposIte direction. This will need to be reversed by the greater use of bIOlogical processes, including greater use of photosynthesis for fuel produc11on. Reserves are always required but storage is costly and there are advantages in storing energy as polysaccharides, such as the naturally-ocCan. Inst. Food Sci. lechno!. J. Yo!. 12. No. 1, January 1979
Editorial Note: This report summarizes the International Dairy Federation Symposium held May 9-11, 1975 at the Hanna Research Institute, Ayr, Scotland. Proceedings will be published in the Journal of Dairy Research in early 1979. MAT.
Highlights Remarkable pwgress has been made in the study of milk protein biosynthesis and many investigators are studying the regularity role of phosphorylation of caseins in the Golgi apparatus. The proteolytic conversion of {3-casein to y-casein has been almost fully explalOed USlOg sequence analysis and chromatographic peptide analysis. Polyfunctional reaction theory was proposed to elucidate casein aggregation while a new hypothesis indicated similarity between Caa, ,-caseinate aggregation and isoelectric coagulation. Monomer-polyrner equilibriums of K- and {i-caseins have been studied. Using a new sedimentation equilibrium technique. it was proved that K-casein is dissociated first then bound with {3,,casein forming a complex prior to exertion of the stabilizing ability. A new approach using controlled-pore glass column chromatography for casein micelle study was suggested. and in conjunction with hydroxyapatite chromatography, the composition of casein micelles has been investigated. The structure of inorganic colloids, Ca phosphate-Ca citrate complex, was studied in relation to casein micelle structure. An excellent method to synthesize artificial casein micelles was also proposed. SESSION A. BIOLOGICAL ASPECTS OF MILK PROTEINS. BIOSYNTHESIS AND SECRETION OF MILK PROTEIN. B. L. Larson University of Illinois, Urbana, U.S.A. This main lecture was a general review of the area. STUDY OF THE PRECURSORS OF THE MAIN OVINE LACTOPROTEINS. J. C. Mercier and P. Gaye lnstitut de la Recherche Agronomique. France
/3-,
The amino terminal sequences of the main lactoproteins (",,-, a, k-caseins. (1-lactoglobulin and a-lactalbumin) synthesized by trans-
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curring cellulose and chitin, characteristic of plants and invertebrate animals. Energy would never be the only cost, however, and could not. therefore, serve as a completely satisfactory currency but it could be the base on which a monetary currency rests (rather as gold was in the past). POL YSACCHARIDES AND HEALTH I. MacDonald De!-'artment of Physiology Guy's Hospital Medical School, London The polysaccharides in the diet can, for convenience, be subdivided into those that are non-digestible and those which are to be broken down by the gut enzymes into monosaccharides and thus absorbed into the blood. The non-digestible polysaccharides have received considerable prominence recently due to the speculation that their absence from the diet is the cause of many of the diseases peculiar to the Western World. Evidence for this is rather limited. The digestible polysaccharides are useful adjuncts to the diet as they provide bulk, are cheap sources of energy and lack the osmotic properties of the constituent monosaccharide, glucose. Polysaccharides are accused of causing excess depositions of body fat. Not all carbohydrates may be equal in this respect and may, in children in the tropics, lead to a type of malnutrition. There is evidence that polysaccharides have different effects from sucrose and glucose on lipid metabolism in the body. The skin lipids are also affected by the type of carbohydrate eaten.
A SUMMARY OF THE INTERNATIONAL DAIRY FEDERAnON SYMPOSIUM Shuryo Nakai Professor Department of Food Science University of British Columbia Vancouver, B.C. V6T 1W5
SOME ASPECTS OF FOOD LEGISLATION WITH PARTICULAR REFERENCE TO STABILIZERS AND THICKENERS A.Overeem Hercules Europe S.A.. The Hague, Netherlands The author discussed the following topics: 1. The position of additives in the food acts of some European countries. 2. Codex Alimentarius criteria and lists of approved additives. 3. E.E.C. lists of approved additives. 4. The E.E.C. Directive of Emulsifiers, Stabilizers, Thickeners and Gelling Agents. 5. Adaptation of national legislation of the member states to this Directive. 6. How to obtain approval for a new polysaccharide in food. SESSION 6. SOCIAL AND NUTRITIONAL ASPECTS POLYSACCHARIDES-THE WORLD'S ENERGY CURRENCY RESERVE C.R.W. Spedding Department of Agriculture and Horticulture University of Reading Money is an energetically efficient currency, requiring the minimum expenditure of energy in the exchange of goods. However, it is possible that future values can be more soundly based on the recognition that energy supplies will become scarcer and more expensive. Energy differs from all other resources in that every human activity involves it-including the search for more of it. Short of a technical break-through in the energy cost of obtaining energy. supplies are bound to increase greatly in cost and this may dominate all other costs. This suggests that there will be greater emphasis on the use of solar radiation but this also involves materials which in turn cost energy. Thus, future calculations might best (or additionally) be made in energy. as a kind of currency rather than monetary terms. partly because they will then be more likely to reflect future monetary values. A major aim must be to live within our solar energy income, rather than on capitaL but agricultural systems have been developing in the opposIte direction. This will need to be reversed by the greater use of bIOlogical processes, including greater use of photosynthesis for fuel produc11on. Reserves are always required but storage is costly and there are advantages in storing energy as polysaccharides, such as the naturally-ocCan. Inst. Food Sci. lechno!. J. Yo!. 12. No. 1, January 1979
Editorial Note: This report summarizes the International Dairy Federation Symposium held May 9-11, 1975 at the Hanna Research Institute, Ayr, Scotland. Proceedings will be published in the Journal of Dairy Research in early 1979. MAT.
Highlights Remarkable pwgress has been made in the study of milk protein biosynthesis and many investigators are studying the regularity role of phosphorylation of caseins in the Golgi apparatus. The proteolytic conversion of {3-casein to y-casein has been almost fully explalOed USlOg sequence analysis and chromatographic peptide analysis. Polyfunctional reaction theory was proposed to elucidate casein aggregation while a new hypothesis indicated similarity between Caa, ,-caseinate aggregation and isoelectric coagulation. Monomer-polyrner equilibriums of K- and {i-caseins have been studied. Using a new sedimentation equilibrium technique. it was proved that K-casein is dissociated first then bound with {3,,casein forming a complex prior to exertion of the stabilizing ability. A new approach using controlled-pore glass column chromatography for casein micelle study was suggested. and in conjunction with hydroxyapatite chromatography, the composition of casein micelles has been investigated. The structure of inorganic colloids, Ca phosphate-Ca citrate complex, was studied in relation to casein micelle structure. An excellent method to synthesize artificial casein micelles was also proposed. SESSION A. BIOLOGICAL ASPECTS OF MILK PROTEINS. BIOSYNTHESIS AND SECRETION OF MILK PROTEIN. B. L. Larson University of Illinois, Urbana, U.S.A. This main lecture was a general review of the area. STUDY OF THE PRECURSORS OF THE MAIN OVINE LACTOPROTEINS. J. C. Mercier and P. Gaye lnstitut de la Recherche Agronomique. France
/3-,
The amino terminal sequences of the main lactoproteins (",,-, a, k-caseins. (1-lactoglobulin and a-lactalbumin) synthesized by trans-
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