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The value of milk hinges on its physicochemical functionality under processing conditions. We examined composition-functionality relationships with individual milks from 24 New Zealand dairy cows, sampled at 3 times over the season. Milks were classified into type A or B, according to the shape of 3-point heat coagulation time versus pH profiles. Milk type changed over the season for half of the cows in the study. Best subsets regression suggested that different factors controlled heat stability in the 2 milk types. Urea concentration was key for both types, but for type A milks, osmotic pressure and milk solids were the most important predictors of heat stability, whereas casein micelle size and ionic calcium predicted heat stability for type B milks. This study revealed that milk type is prone to change over the season, and the findings suggest that optimizing heat stability could be achieved by different means for type A versus type B milks.

peer-reviewed The effect of pH, adjusted using either hydrochloric acid (HCl), citric acid or sodium hydroxide, on calcium ion (Ca2+) activity, and consequent changes in viscosity and heat coagulation time (HCT) of milk protein concentrate (MPC) was investigated. Reducing the pH of MPC dispersions resulted in a reduction in their viscosity, which subsequently increased during heat treatment. The maximum heat stability of MPC was observed at pH 6.7. Reducing the pH of MPC from 6.7 to 6.2 resulted in a significant (P < 0.05) increase in Ca2+ activity, and reduction in HCT. Such changes were more extensive using HCl compared with citric acid. Increasing the pH greater than 6.7 also led to a reduction in HCT but a decrease in Ca2+ activity. These results demonstrate the importance of pH adjustment, and choice of acidulant, on Ca2+ activity, viscosity, and heat coagulation properties of MPC concentrates during processing.

peer-reviewed The effects of key manufacturing steps (heat treatment, evaporation and spray drying) during the manufacture of low- and high-heat skim milk powders (SMP) on the physico-chemical and processing characteristics of milk, and concentrates of varying total solids (TS) levels prepared by reconstituting the milk powders, were evaluated. Milk heat treatment had the most pronounced effect, with an increase in severity of heat treatment from 72 °C × 15 s to 120 °C × 120 s, prior to evaporation resulting in higher heat coagulation time (HCT) at pH 6.3–6.6 and ethanol stability (ES) at pH 6.2–6.6, and a marked deterioration of rennet-induced coagulability. Increasing TS of the milk on reconstitution from 9.4 to 25% reduced HCT at pH >6.3 and ES at pH 6.6–7.0, increased ES at pH 6.2–6.4, and led to partial recovery of rennet-coagulability. The results highlight how heat treatment may be used to customise the functionality of SMP to different applications.

Oil-in-water emulsion systems formulated with plant proteins are of increasing interest to food researchers and industry due to benefits associated with cost-effectiveness, sustainability and animal well-being. The aim of this study was to understand how the stability of complex model emulsions formulated using lentil proteins are influenced by calcium fortification (0 to 10 mM CaCl2) and thermal processing (95 or 140 &deg, C). A valve homogeniser, operating at first and second stage pressures of 15 and 3 MPa, was used to prepare emulsions. On heating at 140 &deg, C, the heat coagulation time (pH 6.8) for the emulsions was successively reduced from 4.80 to 0.40 min with increasing CaCl2 concentration from 0 to 10 mM, respectively. Correspondingly, the sample with the highest CaCl2 addition level developed the highest viscosity during heating (95 &deg, C &times, 30 s), reaching a final value of 163 mPa&middot, s. This was attributed to calcium-mediated interactions of lentil proteins, as confirmed by the increase in the mean particle diameter (D[4,3]) to 36.5 &micro, m for the sample with 6 mM CaCl2, compared to the unheated and heated control with D[4,3] values of 0.75 and 0.68 &micro, m, respectively. This study demonstrated that the combination of calcium and heat promoted the aggregation of lentil proteins in concentrated emulsions.

One of the main changes that occur during heat treatment of milk is whey protein denaturation, which in its turn may lead to protein aggregation and gelation. In this contribution, the effect of lysophospholipids, the main components of lysolecithins, as well as alternative surfactants, on heat-induced whey protein aggregation has been studied. Hereby, attention was paid to the relation between polar lipid molecular structure (e.g. effect of alkyl chain length, effect of polar head group) and heat-stabilising properties. Residual protein determination in the supernatant obtained after centrifugation of heated whey protein solutions learned that whey protein aggregation was at least partly prevented in the presence of surfactants. As the short alkyl chain lysophospholipids were particularly effective heat stabilisers, hydrophilic surfactants seemed to be most effective, which may be ascribed to their higher critical aggregation concentration. Upon more severe heat treatment, protein aggregation was probed either in-situ by oscillatory rheology, or ex-situ by yield rheometry. As some surfactants significantly reduced the gel strength, or even prevented heat-induced gel formation, these experiments corroborated the heat-stabilising effect of hydrophilic surfactants. Nuclear Magnetic Resonance (NMR) enabled a more direct evaluation of the protein–surfactant interaction. A strong hydrophobic interaction between small molecular weight surfactants and whey proteins became obvious from the chemical shift of the surfactant hydrophobic groups in the NMR spectrum and could be quantified by pulsed field gradient NMR (pfg-NMR) diffusiometry. The results indicated that protein–surfactant interaction did not occur upon thermal denaturation, but already took place at room temperature. However, the effect of this interaction became mainly obvious during thermal treatment. Overall, this work indicated that bound surfactants largely minimise heat-induced protein intermolecular interactions and hence prevent heat-induced protein aggregation. As the surfactant molecular structure plays a decisive role, it follows that the heat stability of whey protein containing products may be optimised by appropriate selection of ingredients such as (lyso)phospholipids.

Paneer represents a South Asian variety of soft cheese prepared by acid and heat coagulation of milk. It is popular throughout South Asia and used in the preparation of a number of several culinary preparations and snacks. It is a rich source of high quality animal protein, fat, minerals and vitamins. Due to availability of different types of milk and variation in milk composition, various techniques have been developed for the production of paneer as per the requirements of the consumers with appreciable improvement in the yield and other quality characteristics. Some of the modifications recommended in the preparation of paneer are discussed in this review. Examples of some ‘value-added’ paneer have been dealt.

The thermal stability and physico-chemical properties of individual buffaloes’ colostrum (5 animals) were followed during three days after postpartum. The heat stability of the first postpartum milk can be visually defined in terms of the time required to induce coagulation at boiling temperature. Gradually marked variations of heat coagulation time were detected up to 60 h postpartum milking when heated at boiling temperature. The thermal stability of individual buffalo’s colostrum gradually increased with progressive postpartum milking, namely, at 1 h (0.55 min.), 6 h (3.53 min.), 12 h (7.10 min), 24 h (12.30 min), 36 h (18.10 min), 48 h (21.05 min) and 60 h (24.13 min). But at 72 h postpartum, no visual change (coagulation) was observed during heating at boiling temperature for one hour. It can be seen that first postpartum milk was very unstable to heat treatment with coagulation at boiling temperature. Hydrometer is a simple, rapid and of low cost method to evaluate the quality of colostrum. Colostral immunoglobulins concentrations measured from one partial to third consecutive complete milking at 12 h intervals postpartum decreased at different rates over time or number of milking. The colostrum is thicker, stickier and slightly yellowish compared to normal milk, the specific gravity was higher than that of normal milk and the pH is lower. The total solids, total protein, fat and ash contents were highest after parturition and then decreased rapidly to reach values of normal milk almost after three days of parturition, where the protein content was the most variable constituent. While the changes in the lactose content followed an opposite trend.

The 1H-magnetic resonance imaging technique was applied for monitoring the extent of the heat coagulation in the shell egg. It is demonstrated that spin-spin relaxation time (T2) is an effective marker to observe the extent of coagulation in egg white and yolk and that the T2 value image is quite useful to recognize non-destructively the extent and status of coagulation of the heated eggs. This technique can also be applied to the material science as well as food science for observation of the inner status of the objects.

During the last decades, several researchers tried to clarify and fully explain the exact mechanism of the heat-induced coagulation which occurs during heating milk at elevated temperatures. Based on literature data, this phenomenon is mainly a consequence of heat denaturation and unfolding of the globular whey protein fraction of milk, which results in the exposure of the previously buried hydrophobic and free thiol groups. As the denaturation process proceeds, several interactions start to take place leading to the formation of a product with modified organoleptic and physicochemical characteristics. The most important interactions which are believed to take place during heating milk at high temperatures are the interactions between denatured whey proteins with themselves and/or the complex formation of denatured whey proteins (or whey protein aggregates) with casein micelles. The heat-induced network between milk proteins is essentially built due to the hydrophobic bonding between the denatured whey proteins, as well as the thiol-disulfide exchange between the denatured whey proteins with themselves and/or with the κ-caseins. In order to be able to apply high temperatures and at the same time to decrease the degree of protein complexation, the application of surface active molecules (surfactants) has been proposed. Previous studies described that the effect of surfactants on the heat stability of whey protein containing emulsions is based on the protein displacement or interaction with proteins bound on the oil interface, and/or interaction with free proteins in solution.

A CHANGE in pH when proteins are denatured has been reported by other workers1,2. When making observations of the change in pH of meat resulting from heat coagulation, we were struck both by the magnitude and by the variability of the change. Muscle is a highly buffered system3, and a change such as that observed, for example, from 5·6 to 5·9, indicates the production of a considerable amount of base.

To study the mechanism of the gel-strength increasing effect of sarcoplasmic proteins (Sp-P) on fish meat gel, the interaction between each component of Sp-P and actomyosin (AM) occurring during heating was examined. Heat coagulation temperature range was measured for each component by gradually heating the Sp-P extracts (I=0.05) from 9 fish species: 40-50 ℃ for 50K, 43K, and 23K; 50-60℃ for 94K, 60K, 40K, 30K, and 25K; 60-70℃ for 65K, 63K, 55K, and 35K; >70℃ for 20K components>. These components, however, remained in the mixed solution (I=0.7) of Sp-P and AM at a ratio of 1 to 2 even after heating at 80℃. This was attributable to the fact that the coagulable Sp-P components bound to AM molecules one after another at their coagulation temperatures were suspended in the solution.

Caseinoglycopeptides were isolated from sweet cheese whey by alcohol precipitation and ion exchange chromatography after heat coagulation of whey protein. The most successful method for obtaining the highest yield was by heating 10% (wt/vol) whey solution at pH 6.0 for 1h, followed by precipitation with cold ethyl alcohol (50% vol/vol). The caseinoglycopeptide was fractionated into sialo- and asialo-caseinoglycopeptides by peanut ( Arachis hypogoea ) lectin-affinity chromatography. Caseinoglycopeptides exhibited five peaks on reverse-phase HPLC, which were divided into the first peak of an asialo-caseinoglycopeptide and sialo-caseinoglycopeptide in the following four peaks. The ratio of asialo-caseinoglycopeptide in whole caseinoglycopeptide is approximately 10%. Asialo-caseinoglycopeptide also could be prepared from cheese whey acidified to pH 3.0 and heated for 1h at 98°C. Sialic acid in caseinoglycopeptide was completely released by this treatment. The yield of caseinoglycopeptide was approximately 1.1g from 100g of cheese whey powder.

Recent advances have been made in the understanding of factors that control the destabilization of milk proteins by alcohol and by heat. These advances are reviewed, and arguments are developed supporting a physical basis for the mechanism of alcohol-induced precipitation. These physical effects are contrasted with the mainly chemical reaction-based factors controlling heat coagulation. The benefits of these recent developments are illustrated by case studies on cream liqueurs and concentrated milk products.

Antivenoms are preparations of intact or fragmented (F(ab')2 or Fab) immunoglobulin G (IgG) used in human medicine to treat the severe envenomings resulting from the bites and stings of various animals, such as snakes, spiders, scorpions, or marine animals, or from the contact with poisonous plants. They are obtained by fractionating plasma collected from immunized horses or, less frequently, sheep. Manufacturing processes usually include pepsin digestion at acid pH, papain digestion, ammonium sulphate precipitation, caprylic acid precipitation, heat coagulation and/or chromatography. Most production processes do not have deliberately introduced viral inactivation or removal treatments, but antivenoms have never been found to transmit viruses to humans. Nevertheless, the recent examples of zoonotic diseases highlight the need to perform a careful assessment of the viral safety of antivenoms. This paper reviews the characteristics of equine viruses of antivenoms and discusses the potential of some manufacturing steps to avoid risks of viral contamination. Analysis of production parameters indicate that acid pH treatments and caprylic acid precipitations, which have been validated for the manufacture of some human IgG products, appear to provide the best potential for viral inactivation of antivenoms. As many manufacturers of antivenoms located in developing countries lack the resources to conduct formal viral validation studies, it is hoped that this review will help in the scientific understanding of the viral safety factors of antivenoms, in the controlled implementation of the manufacturing steps with expected impact on viral safety, and in the overall reinforcement of good manufacturing practices of these essential therapeutic products. UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto Clodomiro Picado (ICP)

Buttermilk prepared on a laboratory scale from raw cream, or on a commercial scale from flash-pasteurized cream (90 degrees C for 1 to 2 s), exhibited a type B heat coagulation time-pH profile (i.e., stability increased as a function of pH). The high heat stability of buttermilk in the pH range of the minimum of a type A milk (pH approximately 6.8 to 7.0) appears to be related to differences in the serum phase constituents (i.e., a low calcium and beta-Lg concentration and a high nonmicellar kappa-CN content).

Journal of Dairy Research, 59 (2), ISSN:0022-0299, ISSN:1469-7629

A view of the structure of the casein micelle is given. It is built of submicelles, roughly spherical aggregates of several casein molecules held together by hydrophobic bonds and salt bridges. Regions of amorphous calcium phosphate link the submicelles to each other, the ester phosphate groups form part of this colloidal phosphate. In this way, almost all regions of the casein molecules are severely restricted in mobility. The C terminal part of the κ-casein is however predominantly present as flexible "hairs" located at the outside of the micelles. There are essentially two types of submicelles, with and without (much) κ-casein. The casein micelles greatly change in properties upon lowering the pH, mostly due to dissolution of colloidal phosphate; at still lower pH, increased formation of salt bridges predominates. Temperature also has pronounced effects: upon lowering it, the micelles become more voluminous, presumably due to protruding hairs of (mainly) β-casein. Also at high temperature (>70°C), parts of the casein molecules become more flexible. Casein micelles are very stable, If conditions are changed they may disintegrate or aggregate. Aggregation mostly leads to formation of a gel. The application of the theory of fractal floc formation to gelation is briefly discussed: it serves to explain the very strong dependence of gelation times on volume fraction of aggregating particles. The stability against aggregation is primarily due to steric repulsion, caused by the hairs of κ-casein, and at low temperature presumably also pcasein. The hairs on different casein micelles may however touch, and this may lead to lasting contact of the micelles, i.e., aggregation. The bonds formed can be salt bridges or, at high temperature, covalent bonds (chemical crosslinks). Hydrophobic bonds are probably not involved. The probability that casein molecules in different micelles may touch each other for a sufficient time for bonds to be formed appears to depend on electrostatic as well as steric repulsion, which thereby affect aggregation rate.

The heat coagulation of water soluble proteins from walleye pollack, rat-tail, morid fish, eel-pout, halibut, and mackerel was examined to compare the difference in thermostabillty among fish species. From the thermodynamic parameters accompanying the heat coagulation process, it was shown that van't Hoff plots gave two lines with different slope in the temperature range of between 50° to 60°C. The ΔG° of walleye pollack, rat-tail, and morid fish showed the negative values at both 50° and 80°C. The results suggested that the thermostability of these fish proteins was lower, compared to that of the other fishes examined. The thermal reaction at 50°C resulted in a large value of the ΔS°.

Leaves are, and will probably remain, an important dietary source of β carotene (provitamin A). There is enough of it in extracted leaf protein (LP) to make that a useful source. β carotene is rapidly destroyed when LP, especially from young leaves, is preserved with salt. Destruction can be partly prevented by avoiding contamination with iron during preparation, by coagulating LP by heating rather than acidification, and by treatment with chelating agents. The unsaturated fatty acids in leaf lipids seem not to be involved in the destruction.

In the sterilizing process in the manufacture of evaporated milk, it is desirable to produce an incipient coagulation, in the nature of a tender jell or "fiver" as it is called by the practical men. Such a product will have a heavy creamy body after the "fiver" has been broken up by the shaking process. This is desirable because the product presents a richer appegrance to the consumer, and on account of the greater viscosity, there is little danger of fat separation from such a product. However, evaporated milk differs widely in the readiness with which it coagulates. At times the milk coagulates so readily that it would be unmarketable, on account of its curdy appearance, if it were heated long enough to preserve it. This constitutes the problem with which we are concerned in this paper. There is probably no condensery that is entirely free from this trouble throughout the year. I t is undoubtedly one of the biggest problems that confronts the industry.

Summary The variations in the time of coagulation with variations in the temperatures used have been shown to be of a logarithmic nature. However, these variations in the time of coagulation are less with milk of 9 per cent solids-not-fat than they are when milk of 18 per cent solids-not-fat is used. The results indicate also that the use of temperatures of from 110° to 120° C. yield results of greatest practical value. Higher temperatures are apt to give results wherein the errors are large. 2. The data presented upon forewarming also indicate that the concentration of solids-not-fat is an important factor in varying the relative effects of this procedure. The results show that forewarming at high temperatures lowers the stability of those of higher solids-not-fat concentration. Hence, in any comparison of results obtained with milks of different solids-not-fat concentration similar treatment with respect to forewarming must be assured. These results indicate also that the relationships established by forewarming are not altered by the addition of electrolytes except in degree of stability. It appears, therefore, that forewarming does not affect stability merely through changes in the equilibria of the soluble salts, as the stability cannot be restored by the addition of electrolytes in those cases wherein it has been reduced. 3. The results show conclusively that the heat stability of a milk of 18 per cent solids-not-fat concentration cannot be predicted from the heat stability of the original milk. They show further why the use of phosphates as a "neutralizer" has not led to serious trouble. In those cases wherein its use has not materially improved stability its use has not greatly reduced it. 4. The existence of two types of milk, one stabilized by the addition of positively charged electrolytes and the other stabilized by the addition of negatively charged electrolytes, has been confirmed. The effect of the addition of various electrolytes to these types of milk has been studied over a wide range of concentration and it has been shown that in the lower concentrations they are most sensitive to the effect of di- tri- and quadrivalent ions and the monovalent H-ion while in the higher concentrations the monovalent K-ion is also very effective. The relationships of these effects are similar to those found for As 2 S 3 sols. Hence it again seems to have been shown that the calcium caseinate suspension in milk is analogous to hydrophobic sols in its reactions with electrolytes at higher temperatures. Increased stability has been shown to result from the addition of citrates and phosphates to a milk stabilized by negatively charged electrolytes. Finally, complete data have been presented upon the effect of various electrolytes upon the two types of milk at 9 and 18 per cent solids-not-fat concentrations. In general, a study of the data presented shows clearly that in studies on coagulation careful consideration must be given to phase concentrations and that conclusions drawn from work on milk of one concentration are not applicable to other milks of widely different concentrations. Furthermore, at the lower concentrations of solids-not-fat various electrolytes exhibit critical.concentrations or ranges wherein their effect is great. Hence, any work which does not include results over a range of concentration of electrolyte as well as range of concentration of the sol used is apt to lead to erroneous conclusions.

The usefulness of 14 common organic solvents in lowering the temperature necessary for the heat coagulation of serum proteins is evaluated. Six of the compounds, when added to serum in final concentrations varying from 14.3 to 28.6% (v/v), result in the formation of a firm clot at 60°. Ethylene glycol monomethyl ether is effective at 50° at 22.8% (v/v). Lower concentrations are effective at higher temperatures. The boiling points of the six range from 65° (methanol) to 153° (N,N-dimethyl formamide).

The need for further studies on heat coagulation became apparent during attempts to measure the influence of various electrolytes upon the coagulation temperature of various milks. The data available proved rather limited, and attempts to check certain published results were only partially successful. A lack of uniform methods, it is felt, largely accounts for the differences obtained by various workers. In the present study, the method adopted was carefully standardized, in an attempt to minimize the error in judgment regarding the point at which coagulation first occurs. Goat's milk as well as cow's milk was used.

The sterilization processes used in the manufacture of evaporated milk are designed not only for sterility but for those physical characteristics which improve the quality of the milk. As a rule, most manufacturers of evaporated milk grade the sterilized milk in terms of viscosity, grain and color; the relative importance assigned to these properties varies, depending on the point of view of the manufacturer. In the quest for improved sterilization processes, the lack of organization of processing data has been an impediment to a comprehensive understanding of the :;terilization process. A knowledge of the relationship existing between the color. viscosity, grain formation and surface tension for processes in general would assist greatly in predicting the effects of contemplated changes in processing. Considerableattention has been given to the problems arising in the steriliza'don of milk. Bell et al. (1) found that high temperature-short time sterilized evaporated milk thickened on storage, but if the milk was filled into cans after the high temperature-short time sterilization process and the color increased by further heating, the gelation tendency was reduced greatly, if not eliminated. Holm et al. (3) determined the relationship between the cooking time and the temperature necessary for coagulation. Later, the logarithmic nature of the heat coagulation was noted by Webb and Holm (5) in test tube experiments. While many of the phenomena associated with the processing of evaporated milk are recorded in the literature, little if any attention has been given to the character of the heat coagulation or its relationship to color, viscosity and surface tension. The purpose of this paper is to examine the results obtained in various sterilization processes with reference to grain formation, surface tension, viscosity and color and to show the relationship of these measurements to one another.

Summary The relationship between the heat stability and the composition and other properties of the milks of four cows during the course of a lactation period was investigated. No marked correlation was found between the heat stability and the various tests and analyses conducted upon the milks. The "rapid" tests sometimes used to classify milks to be used for condensing, such as the acid test, the alcohol test, and the phosphate test, did not satisfactorily indicate the relative heat stability of the milks. The salt balance as determined by analyses of the milks showed no direct correlation with the heat stability of the samples. The buffer intensity was not related to the stability of the milks toward heat. No clear relationship was noted between the heat stabilities of the fresh milks and of their evaporated products. Each of the individual milks for the most part retained fairly constant values in many of the tests, these values being characteristic of the milk from each cow. The results of this investigation of the individual milks of four cows conclusively demonstrated the inadequacy of our present knowledge of the heat stability of milk.

Summary Laboratory experiments in which high temperature-short time sterilization of concentrated milk was carried out under static conditions showed that heat and storage stability were at times adversely affected by the presence of a lipid phase. Three types of milk were encountered. The predominant type (if forewarming was employed) consisted of milks in which the fat phase behaved as an inert phase, that is, the processed whole and the corresponding processed skimmilks were heat-stable and resisted gelation during storage to approximately the same degree. On occasions, a type of milk was encountered in which the processed whole but not the corresponding processed skimmilk coagulated during sterilization. On other occasions, a type of milk was met in which the processed whole milk had a slightly greater shelf-life than the corresponding processed skimmilk. Exchanging the fat globules belonging to a heat-stable for those in a heat-labile milk tended to reverse the order of stability. Substitution of fat for an equal weight of protein showed that both heat stability and storage stability were significantly decreased by the substitution. Milks prone to coagulate because of an unstable lipid phase were stabilized to some extent by forewarming against both heat coagulation and gelation during storage. Mixing of forewarmed and unforewarmed milks resulted in composite milks with heat and storage stabilities intermediate between those of the unmixed milks. Milks reconstituted from butter oil and skimmilk were stabilized by the addition of fat-soluble interfacially active mixtures to the butter oil. Sterilization under static conditions yields results which, supplementing the results of sterilization under turbulent canditions, allows one to isolate the effect of heat from the combined effect of heat and turbulent flow.

Mineral salts have effects on the heat coagulation of proteins, and presumably on that of wort proteins. To ascertain the effects of each individual salt it is desirable to start with wort which is free from salts. To obtain such wort, recourse was had to electrodialysis to remove the salts actually present in wort. During this process a protein was precipitated. This was separated, purified and investigated. The results indicated that it consisted of nucleoprotein, was insoluble in the absence of mineral salts at Ph 3.9, but increasingly soluble at reactions more alkaline than Ph 5.0. It was also coagulable by heat. A small quantity of another protein which remained dissolved at the end of the electrodialysis was separated by magnesium sulphate precipitation and proved to be soluble in water and not coagulable by heat.

A method for the quantitative separation of serum urate from the proteins present, that does not employ chemical precipitation, is presented. The separation is accomplished by heat coagulation of serum and the subsequent aqueous extraction of the purine from the intact coagulum. Serum is placed at the bottom of a container of sufficient size to permit the formation of a thin layer and then coagulated in a boiling-water bath. The resultant coagulum is firm, adherent to the container, and not easily disrupted. Water is then added to cover the coagulum and the urate extracted. The urate present in the extract is determined using a phosphotungstate reduction method.

1. It was found that there are two Hb's (component F and S) in blood of chum salmon, the ratio of these Hb's in amount being almost constant (component F 55 to component S 45). 2. Component F and S were separated from each other by means of starch electrophoresis and some properties were compared with each other. Component S is less anionic electrophoretically, more soluble in phosphate buffer, more resistant to heat coagulation, and moved slower in column chromatography than component F. The near ultraviolet spectra of component F shift towards longer wavelengths than those of component S.

It is supposed that there are some relationships between the physico-chemical properties of fish meat paste containing salt and that of the fish jelly produced by steaming the paste. The authors have devised four laboratory tests by means of adhesive power and resistance on push-in for the paste1), and depression- and breaking-strengths for the jelly2). For the test, an amount of meat from the great blue shark, prionace glaucus LINNE, was divided into a few groups of samples and left to stand for lengths of time to let them deteriorate to different extents. Each sample was in turn processed into paste in a strictly uniform manner which included chopping, adding 2.5 par cent of NaCl, and grinding it up. After taking the measurements stated above, the paste was turned to a fish jelly by steaming for 20 minutes. Then measurements of depression and breaking strengths of it. The results from measurements of all the samples revealed that adhesive power and resistance on push-in of the paste decrease in accordance with deterioration of material meat, and that strengths in depression and breaking weaken in parallel with the above decreases. A series of hypotheses on the mechanism of variation in physico-chemical properties of the products have here drawn out of discussion on the properties in relation to chemical deterioration of muscle proteins. When the chopped fish meat is ground with salt (NaCl), the muscle proteins seem to transform from a gel into a sol and acquire a marked stickiness. That adhesive power of the paste decreases with the deterioration of material meat is attributable to the denaturation of myosins, and thus to the decrease in the amount of myosins dispersing in the paste. As a result, the paste, when turned into a jelly after heat coagulation, would be more or less prevented from forming a well developed structure of network. The last may explain variation in jelly strengths. On standing the sticky paste falls into “setting” which was found to take place as the loss of stickiness and as the increase in elasticity. When the curve in Fig. 3 are examined, modes of the setting may be classified into three types which are likely associated with different grades in freshness of material meat. Chmeical explanations given to this fact have come in harmony with the above view bared on the denaturation of myosins. 1) Bull. Jap. Soc. Sci. Fish., 18, 319-326 (1953). 2) Ibid., 17, 377-384 (1952).

The results were summarized as follows: (1) The commercial cation exchange resin used in this study was showed to have a usable maximum capacity amounting to 0. 587g of calcium per 20g of the resin. The procedure of Ca→Na regeneration of the exchange resin adsorbing calcium was tested, and it was found that the indirect procedure in wich the regeneration was done in the way of Ca→H→Na with HCl and NaCl solution was more profitable than the direct one with NaCl solution alone. (2) In respect of a salt solution mixed at the same rate as mineral salts in milk, experiments of the exchange resin treatments were performed. It was found that calcium was preferentially exchanged close to the theoretical value and there was hardly any effect of other cations. (3) Experiments treating milk with the exchange resin were carried out concerning to the relations between volume of milk, velocity of the blow, acidity and pH of the milk, and the rate of calcium removed. It was shown that the higher the rate of calcium removed, the lower the temperature of heat coagulation of treated milk, whereas the opposite case was existed in a special example.

A direct ultraviolet absorption method that does not require uricase for the determination of serum urate is presented. Serum (0.3 ml.) is placed in the bottom of a 25 X 95-mm. shell vial and coagulated by immersion of the vial in boiling water for 2 min. The clot is overlaid with 3.0 ml. of water and the serum urate extracted for 60 min. at 37°. The absorbance of the extract is measured at 295 mµ, and the serum urate determined by comparison with the known absorption of pure urate at the same wavelength. The agreement between the direct ultraviolet method and a standard phosphotungstate reduction method is excellent in cases in which no medication is being administered. Some drugs absorb ultraviolet light, and in certain instances may be responsible for a discrepancy up to 1.5 mg./100 ml. between the two procedures. The method is extremely simple and requires no reagents.

The fish muscle increases in weight while it keeps the freshness, by absorbing water when it is cooked in water. And if this heated muscle is soaked in saline water, the increase in weight becomes more intense. The changs seems to be greater when it is cooked in higher temperature. On the other hand, if the temperature reaches to a certain limit, the muscle decreases in weight, while in the former case it increases, owing to the heat coagulation of protein. As a result of the composition of these opposite actions, a peak appears on the hydrating curve. the peak becomes low more rapidly in accordance with rising of the previous temperature and moves into the lower side of the temperature as the time of pickling extends. The maximum point of the dehydrating curve lies at near 60° which corresponds with the coagulating point of myogen. And the curve corresponding the coagulating point of myosin doesn't appear. We consider, therefore, that there is only one kind of coagulable protein in fish muscle while it is fresh.

Summary 1.The results of the first part of the work where only milk cultures of the sweet curdling organisms were used can be summed up as follows: a.Small amounts of acid inhibit heat coagulation over a small range. b.Larger amounts of acid increase heat coagulation. c.Small amounts of a milk culture of a sweet curdling organism inhibit heat coagulation over a small range. d.Larger amounts of a milk culture of a sweet curdling organism hasten heat coagulation. e.In the presence of little acid the addition of portions of a milk culture of a sweet curdling organism lowers the acidity at which heat coagulation will take place. f.In the presence of larger amounts of acid this action of the culture of a sweet curdling organism is obscured or eliminated. 2.The results of the second part of the work when the rennin-like enzymes of certain bacteria were isolated and purified are as follows: a.The rennin-like enzymes of sweet curdling organisms were isolated and purified to some extent by methods described. b.Bacterial rennin is destroyed by a temperature of 60°C. for fifteen minutes. c.The purified bacterial rennin has no effect upon heat coagulation when the milk is heated immediately upon addition of the rennin. d.When the rennin has been allowed to act on the milk for a time, the heat coagulability of the milk is increased. e.The rate of this action of the rennin is dependent on the concentration or strength of the enzyme present. f.The rate of action of the rennin is dependent on the temperature at which the enzyme is allowed to act. A temperature of 40° to 43°C. is the optimum for most remains. An increase in temperature up to the optimum temperature hastens rennin action. Action goes on at a slow rate at temperatures as low as 10°C. g.The addition of acid in small amounts accelerates the rennin action. h.The presence of soluble calcium salts in small amounts accelerates the rennin action. i.The presence of citrates in small amounts retards the rennin action. j.The effect of acid plus rennin upon heat coagulation is additive. k.The effect of soluble calcium salts plus rennin upon heat coagulation is additive. l.A definite amount of curdling enzyme can cause heat coagulability only in a limited amount of milk. m.This limit of influence is the same whether the rennin is allowed to complete its action at its optimum temperature or autoclave temperatures are applied after the action is started. n.Chymosin resembles the bacterial rennins in its influence upon the heat coagulation of milk. o.Bacterial rennin may be an important factor in the coagulation of milk upon sterilization in the condenseries. The rennin may work in conjunction with acid in the milk or an excess of soluble calcium.

Rice plants (Var. Aichiasahi) were grown in pots under 8 different nutrient conditions as follows : (1) Full nutrients (F), (2) Nitrogen only (N), (3) Phosphorus only (P), (4) Potassium only (K), (5) Without Potassium (NP), (6) Without Phosphorus (NK), (7) Without Nitrogen (PK), (8) No nutrients (O). Leaves of the definite orders were sampled from the seedling of all plots and then "heat coagulation method", which has been devised one of the authers, was applied as follows : The sampled leaves were ground out carefully and the solution were diluted by adding 30c.c. dist. water per 1gr. green weight. After filtrating it, 5c.c. solution was taken and at 60°C in the water bath. At the sametime, another 5c.c. solution was taken and added with 0.5c.c. of 10% NaCl solution as coagulater before heating as above. Then the time required for the appearance of coagulantion was measured. It was found that the coagulation generally appearance earlier in the plots which containd nitrogen such as F, N, NP, NK, than in those without nitrogen such as P, K, PK, O. Moreover, this tendency was recognized with the plants at any stages of growth as far as this experiment goes.