Curd Tension Research Articles

The Relationship Between the Curd Tension of Milk and Gastric Emptying Time in Children

The Relationship Between the Curd Tension of Milk and Gastric Emptying Time in Children

A series of substitutes for milk in the treatmentof allergies

Summary In eczema, especially infantile eczema, milk allergy plays a major role. The majority of eczematous infants react to the curd of milk whether there is sensitivity to the casein alone or sensitivity to both casein and lactalbumin. Casein of both cow's milk and goat's milk is almost identical immunologically. Because of the greater proportion of casein in cow's milk than in human milk, there is a greater chance of casein sensitization. Soybean flour varies widely in protein, fat, and phosphorus content. Therefore, to avoid variations in soy formulas, processing of the flour must be investigated throughly before using as the base for “soy milk.” The literature has demonstrated the necessity of the addition of both calcium and phosphorus to milk substitutes rather than calcium alone. equal to or greater than equivalent amounts of calculated formulas made with milk and added carbohydrate. Gelatin as a complementary protein fortification rather than as a sole source of protein seems adequate. The increased absorptive ratio of vegetable oils over butter fat makes such fortification desirable. Correct physical constitution of the substitutes with surface tensionapproximating that of milk, curd tension that of a soft curd milk, and pH about the neutral point has been attained. These substitutes combine the advantages of a soft curd milk with the advantages of an acidified milk. The palatability, fluidity, low cost, ease of availability, and ease ofpreparation are all exemplified in the comparative lack of difficulty with which these preparations have been offered to both the patient and the one preparing the formula.

297. The firmness of rennet curd; its measurement and variations

A method is described for the measurement of the firmness of the rennet curd from 100 ml. samples of milk coagulated under conditions simulating those of the cheesemaking process. Tests with a series of homogeneous curds ranging in firmness from very soft to very hard showed that the curds behaved as elastic gels of varying modulus, and the deformation produced under a suitable compressive load was accordingly adopted as a simple objective measure of firmness.The method was used to observe the variation in the curd firmness of samples of milk from individual cows and separate quarters, with some observations on the relationship between curd firmness and milk composition, and the effect on curd firmness of variations in the following factors: acidity, addition of calcium chloride, amount of rennet, time of coagulation, and the admixture of soft-curd milk.The results of these experiments indicate that the method provides a satisfactory measure of the rennet curd firmness of small samples of milk. The utility and applications of the method are discussed, and the suggestion is made that a standardized reproducible test on the same principle should be evolved to serve the same function with regard to milk for cheese making as the standardized measurement of curd tension serves with regard to the digestibility and suitability of milk for infant feeding.

Soft curd homogenized milk in infant feeding: A laboratory and clinical study

Summary Pasteurized milk homogenized by means of (a) the sonic homogenizer,(b) the low pressure homogenizer, and (c) the high pressure homogenizer in accordance with sound principles of milk technology has been compared with boiled pasteurized milk as a base for infant formulas, using both laboratory and clinical techniques of observation. Each of these milks containing added carbohydrate was fed unboiled and undiluted to over 200 infants for from two to twelve months. There was a low incidence of constipation, diarrhea, vomiting, and kindred gastrointestinal upsets in all groups, and the babies grew and thrived normally. In digestibility and safety the homogenized milks proved as satisfactory as the control boiled milk. Laboratory studies demonstrated that by use of holding pasteurizationtemperatures of from 150 to 160° F. for thirty minutes, the bacterial counts of homogenized milks can be kept at low levels, usually below 2,000 per milliliter, with resulting high sanitary quality and without the introduction of an objectionable heated flavor. The curd tension and related values fluctuated with the seasons andwere at different levels with each type of homogenized milk, but the changes and differences did not give rise to detectable clinical disturbances. In the light of this finding and related observations recorded in the literature, the suggestion is made that there exists a threshold or dividing zone which delimits readily digested or soft curd milks from less thoroughly processed milks or from plain pasteurized milk.

An Analysis of the Relationship Between the Curd Tension and the Curd Surface Area of Milk

Summary Within individual types of commercially modified milks there appears to be no significant correlation between curd tension and curd surface area. Within mixed groups of various types of modified milk the relationship between curd tension and curd surface area is of variable significance and seems to depend upon the types of milk included in the particular group. It appears that curd tension and curd surface area are independent characteristics of milk and that each may be influenced or determined by factors not closely related.

The Significance of Lipolysis in the Curd Tension and Rennet Coagulation of Milk. I. The Role of Fat Globule Adsorption “Membrane.” II. The Effect of the Addition of Certain Fat Acids to Milk

The Significance of Lipolysis in the Curd Tension and Rennet Coagulation of Milk. I. The Role of Fat Globule Adsorption “Membrane.” II. The Effect of the Addition of Certain Fat Acids to Milk

The Effect of Curd Tension of Milk on the Utilization of Added Vitamin D

The Effect of Curd Tension of Milk on the Utilization of Added Vitamin D

Effect of Free Fat Acids of Milk Fat on Curd Tension of Milk. Relation to Milk Esterase, Temperature, Use of CaCl2, Kind of Fat Acid, Milk Lipase and Churning

Effect of Free Fat Acids of Milk Fat on Curd Tension of Milk. Relation to Milk Esterase, Temperature, Use of CaCl2, Kind of Fat Acid, Milk Lipase and Churning

Changes Observed in Milk “Sham Fed” to Dairy Calves

Summary 1. Pasteurized and superheated whole milks and separated milk were “sham fed” either from open pails or through nipples to fistulated calves. 2. A comparison of the properties of various samples of “sham-fed” milks with properties of their respective controls revealed in the case of pasteurized whole milk increases in rate of rennet coagulation, in tension of the body of the curd, in hydrogen-ion concentration, in lipolytic activity and in cream volume. The corresponding changes in superheated whole milk were in the same direction but of less magnitude. Separated milk manifested a slight increase in the rate of coagulation, an insignificant decrease in curd tension, no pronounced change in hydrogen-ion concentration but a marked increase in lipolytic activity. 3. Further alterations were evident after retention of the samples at 38° C. for two hours. Except for a slight increase in pH there were no marked changes in the control sample of pasteurized whole milk, but in the “sham-fed” samples all initial changes, except for a reduction in curd tension, were further amplified. The trends of all samples of superheated whole milk were in the same direction as in pasteurized whole milk. In the separated milk the only notable change in the control sample was a decrease in curd tension, whereas in the “sham-fed” sample there was a slight increase in rate of coagulation and in curd tension. 4. Several of the pronounced changes in the properties of the whole milk as contrasted to those of the separated milk were attributed in part to lipolysis, a reaction probably resulting from enzymes present in saliva and/or other secretions of the mouth and esophagus. 5. Ingestion of milk through a nipple as compared with consumption from an open pail exaggerated the changes in whole milks but produced little difference, except in increased lipolytic activity, in separated milk. 6. The pre-gastric alterations of milk apparently are of such a nature as to expedite subsequent digestion and assimilation.

An evaluation of enzyme treated milk in infant feeding

<h2>Summary</h2> Market milk was treated with a pancreatic proteolytic enzyme just prior to pasteurization. The addition of the enzyme so reduced the curd tension that boiling, for formulation for infant feeding, was found unnecessary. The curds formed from this milk are soft, flocculent, finely divided, and do not tend to agglomerate. The enzyme treatment does not alter the appearance, taste, or cream line of the milk. This milk has been fed at St. Vincent's and Cook County Hospitals, to the premature, newborn, and older infants during the past three years. It has been used either diluted or undiluted in accordance with the usual method of prescribing infant formulas. Several thousand infants were fed this unboiled milk. Observations did not reveal a single instance of milk intolerance. Curds were rarely seen in the infants' stools. The physicochemical change which takes place when the enzyme is added is not definitely known. It is presumed that some change takes place in the calcium casein bond, resulting in denaturization of the casein. The enzyme is inactivated by pasteurization, just as are the indigenous enzymes of milk. The preparation of an infant's food, using cold unboiled milk, cold water, and cold sugar solutions, eliminates the dangerous bacterial multiplication that occurs during the cooling phase of previously heated solutions. Elimination of boiling large quantities of milk reduces the cost of preparation and refrigeration and materially increases the comfort of the workers in the milk kitchen. Our observation demonstrates that the growth and increase in overall measurements of the infants fed enzylac compare favorably with those in a control group on formulas made with other milks and by other methods. When subjected to statistical analysis, the difference between the two groups is not appreciable. Less diarrhea and fewer infections of the upper respiratory tract occurred in the groups fed cold processed enzylac than in those fed control milks.

Physical and Chemical Properties of the Fat Globule Adsorption “Membrane.” II. Nature and Origin of Surface Active Materials Involved in Curd Tension Reduction and Prevention of Rennet Clot of Cow's Milk by “membranes” from Natural and Synthetic Creams

Physical and Chemical Properties of the Fat Globule Adsorption “Membrane.” II. Nature and Origin of Surface Active Materials Involved in Curd Tension Reduction and Prevention of Rennet Clot of Cow's Milk by “membranes” from Natural and Synthetic Creams

Reduction of Curd Tension of Milk by the Addition of Sodium Salts

Summary A method has been presented for producing milk with reduced curd tension by the addition of certain sodium salts. It is indicated that there is need for further nutritional study of the product before recommending adoption of the method by the industry.

The Use of Sodium Metaphosphate for the Preparation of Soft-Curd Milk

Summary 1.Sodium metaphosphate when added to milk in an average ratio of approximately 41mg. to 100ml. prevents the formation of a curd when the milk is treated with a pepsin-hydrochloric acid coagulant. For the milk samples used the metaphosphate required to prevent curd formation varied from 30 to 52mg./l00ml. of milk. 2.When metaphosphate is added to milk before heating, the amount should be increased to 75mg. per 100ml. of milk. 3.Additional calcium may be added to milk, and zero curd tension maintained by adding metaphosphate. 4.In vitro experiments indicate that metaphosphate-treated milk is more easily digested than untreated milk. 5.Sodium metaphosphate is nontoxic in the doses used. When added to milk it seems to form a soluble complex with calcium that may be absorbed and utilized by the body. 6.The addition of sodium metaphosphate to a diet decreases the calcium excreted in the feces and increases the calcium excreted in the urine. 7.Sodium metaphosphate increases iron absorption from an iron-containing milk diet. 8.Sodium metaphosphate appears to be a safe, simple and economical means of preparing soft-curd milk either in the home or in the dairy. In contrast to the other methods available, this treatment requires no additional equipment and very little additional labor.

Study of Physical and Chemical Properties of the Adsorption “Membrane” around the Fat Globules in Cream. I. the Effect of the Adsorption “Membrane” of Synthetic Creams on Curd Tension of Cow's Milk

Summary Synthetic creams were made by emulsifying pure butter fat in the following aqueous sols: Dried whey sol, skim milk powder sol, calcium caseinate sol, gelatin sol, and tissue fibrinogen (lecithoprotein material) sol. The resulting synthetic creams were dispersed in normal milk plasma to obtain remade whole milks which were separated to give the corresponding remade skim milks and remade creams. The remade buttermilks were prepared by churning the remade creams. The fat globule adsorption membrane from dried whey cream, when released in buttermilk by churning the remade cream, exerted a profound effect on the rennet clot of the buttermilk. This effect was characterized either by the total inhibition of clotting or by the formation of very soft and fragile curd with little or no syneresis. A still more pronounced effect of the fat globule adsorption membrane on the rennet clot of remade buttermilk was found in the cases of gelatin cream and calcium casemate cream. Remade buttermilk from either of these creams invariably had no curd tension whatever and did not show even a visible coagulation on the addition of rennet. Although the addition of CaCl 2 , in rather large concentration, to buttermilks from the above creams restored somewhat their curd tension values, it has been shown by calcium and phosphorus analysis of the papain clot whey from the buttermilk of gelatin cream that the ultimate cause of this phenomenon of low curd tension, or non-coagulation, is more deep seated than that of lack of Ca ++ This being the case the CaCl 2 cannot be regarded as restoring the clotting properties in these experiments simply because it supplies Ca ++ to the system. The fat globule adsorption membrane from skim milk powder cream had only a relatively slight curd tension reducing effect on its remade buttermilk as compared with the effect exerted by the adsorption membrane from dried whey cream. The fat globule adsorption membrane derived from tissue fibrinogen (lecithoprotein complex material) had no effect on the curd tension of remade buttermilk. The phenomenon of total non-coagulation with rennet, or abnormally low curd tension of remade buttermilks, was always accompanied by considerably lower pH and lower surface tension of the remade buttermilks as compared with the pH and surface tension of their respective whole and skim milks. The factors involved in the decreased pH and lowered surface tension and their relation to the loss of clotting ability have been the subject of extensive further study by us. 7 7Part of this further study was a post doctorate work and was done by the senior author in the Dairy Chemistry Laboratory of the Dairy Industry Division, University of California, Davis develop as the result of hydrolysis of esters of these fat acids by esterase in the milk, the normal clotting properties of the milk are inhibited. Other important aspects of these findings will be presented in detail in the papers to follow. It may be stated briefly at this time that the total destruction of the clot in the case of certain remade buttermilks was found to be due largely to the liberation of certain fat acids and their adsorption by the calcium caseinate, preventing the clotting of the milk by rennin. It was also found that curd tension is not seriously affected, if affected at all, by butter fat hydrolysis except when an unnatural emulsifying agent is substituted for the natural fat globule adsorption membrane of cow's milk. Furthermore, when lauric, myristic or palmitic acid is added directly to skim milk or allowed to develop as the result of hydrolysis of esters of these fat acids by esterase in the milk, the normal clotting properties of the milk are inhibited. Other important aspects of the se findings will be presented in detail in the papers to fallow.

The gastrointestinal response of children to testmeals of barium and pasteurized, evaporated, and base-exchanged milks

To determine the relation of gastrointestinal motility to milks of different curd tension, seven healthy children, aged 7 to 11 years, each of whom had been observed previously in an acid-base mineral balance study covering 225 successive days, and whose gastrointestinal motility patterns were known, served as subjects of serial roentgenographic studies upon the orderly passage through the alimentary tract of test meals composed of 2 ounces of barium sulfate and 4 ounces of pasteurized milk, evaporated milk diluted 1:1 with water, and base-exchanged milk. Roentgen examinations were made at frequent intervals until the meal had passed out of the stomach and at twenty-four-, forty-eight-, and seventy-two-hour intervals after its ingestion, a total of 181 exposures. The average gastric emptying times for the seven children were 227,214, 193 minutes, respectively, for pasteurized, evaporated (diluted 1:1), and base-exchanged milks. The roentgenograms taken ten minutes after ingestion indicated that the soft curd milks (evaporated and base-exchanged) began emptying from the stomach in much less time than the pasteurized milks: in nine instances the soft curd milk had reached the duodenum and in four of these had entered the jejunum after ten minutes, while in only one exposure at the 10-minute interval had the pasteurized milk meal left the stomach. The fluffier, more evently dispersed masses formed by the processedmilks, presenting greater surface areas to the digestive juices in the small intestine, and the more orderly progression of these soft curd milks throughout the alimentary canal, are in accord with results of metabolic and clinical observations upon the nutritive advantages of different milks. To determine the relation of gastrointestinal motility to milks of different curd tension, seven healthy children, aged 7 to 11 years, each of whom had been observed previously in an acid-base mineral balance study covering 225 successive days, and whose gastrointestinal motility patterns were known, served as subjects of serial roentgenographic studies upon the orderly passage through the alimentary tract of test meals composed of 2 ounces of barium sulfate and 4 ounces of pasteurized milk, evaporated milk diluted 1:1 with water, and base-exchanged milk. Roentgen examinations were made at frequent intervals until the meal had passed out of the stomach and at twenty-four-, forty-eight-, and seventy-two-hour intervals after its ingestion, a total of 181 exposures. The average gastric emptying times for the seven children were 227,214, 193 minutes, respectively, for pasteurized, evaporated (diluted 1:1), and base-exchanged milks. The roentgenograms taken ten minutes after ingestion indicated that the soft curd milks (evaporated and base-exchanged) began emptying from the stomach in much less time than the pasteurized milks: in nine instances the soft curd milk had reached the duodenum and in four of these had entered the jejunum after ten minutes, while in only one exposure at the 10-minute interval had the pasteurized milk meal left the stomach. The fluffier, more evently dispersed masses formed by the processedmilks, presenting greater surface areas to the digestive juices in the small intestine, and the more orderly progression of these soft curd milks throughout the alimentary canal, are in accord with results of metabolic and clinical observations upon the nutritive advantages of different milks.

Soft Curd Milk : A Critical Review of the Literature

This invention relates to milk which has been rendered more readily digestible by treatment with a proteolytic or a milk curdling enzyme, and has for its principal object the provision of such a low curd tension milk which will stand boiling. A further object of the invention is to provide...

The Effect of Gelatin on the Curd Tension of Milk

Summary In general, increase in the curd tension of milk was accompanied by an increase in casein concentration, although wide variations occurred. The relation of the curd tension to the concentration of the casein seemed to follow approximately an S-shaped curve. The addition of gelatin (Knox) to milk caused a marked fall in curd tension. In most cases, two per cent of gelatin added to milks of curd tension up to about 50 grams converted them to soft curd milks. The reduction in the curd tension of milk increased with increasing viscosity of the gelatin preparation employed. As the jelly strength of the gelatin preparation increased, the reduction in curd tension increased for the porkskin gelatins and decreased for the bone gelatins. A bone gelatin with a high viscosity and a low jelly strength was most effective in lowering the curd tension of milk. The pH was found to have considerable influence on the curd tension. The average curd tension of milk reached a maximum when the pH of the milk before coagulation was between 5.7 and 5.9. In the case of milk which contained five per cent of gelatin, the average maximum curd tension occurred when the pH before coagulation was between 5.6 and 6.6.

Modification of the Bloom Gelometer for Use in the Determination of the Curd Tension of Milk

Summary The Bloom gelometer has been adapted for use in the estimation of the curd tension of milk. It is especially useful in the measurement of very low curd tensions. When the regular pepsin-calcium chloride coagulant of Hill is used, the modified gelometer gives results which agree well with those of the Hill apparatus. If a coagulant consisting of 0.45 per cent of pepsin in 0.09 N hydrochloric acid is used, however, the gelometer under the experimental conditions outlined in this paper gives erroneous results, due, in part at least, to greater retraction of the curd produced by this coagulant.

Curd Tension of Milk and its Relationship to Firmness of Curd in Cheesemaking

Summary In experiments on over 300 samples of milk the following observations were made: The Hill curd test was found not satisfactory for determining the firmness of curd in milk to be used for making cheese. The rennet curd tension as measured by means of the Hill Curd-O-Meter was entirely suitable for this purpose, and the determination of rennet coagulation time was fairly satisfactory. The pH values of milks bore a very definite relation to the rennet coagulation time and to the rennet curd tension, and bore a less definite relation to the Hill curd tension. The pH seemed to be a major factor in influencing the rennet coagulation time, while the percentage of casein was found to be more important in influencing the rennet curd tension. Milks stable to rennet were usually stable to alcohol. Stability to both rennet and alcohol was increased when milk was stored at 2° to 52° C. for from a few hours to several days. Stability to both rennet and alcohol was decreased by the addition of CaCl 2 . Homogenization markedly decreased the rennet curd tension of whole milk but did not change that of skimmilk; this process did not change the rennet coagulation time of either whole or skimmilk. Removal of milk fat by separation increased the rennet curd tension and caused a slight increase rather than a decrease in the rennet coagulation time. These observations lead'to the conclusion that the curd-softening effect of homogenization is due principally to an increase in the dispersion of the fat, the dispersed fat acting as a physical hindrance to the aggregation of the casein molecules and micellae. Pasteurization caused a noticeable softening of milk curd and caused a slight increase in rennet coagulation time. The presence of mastitis caused an increase in pH, an increase in rennet coagulation time, and a decrease in rennet curd tension.

The Effect of the Adsorption “Membrane” around the Fat Globules on the Curd Tension of Cow's Milk

The Effect of the Adsorption “Membrane” around the Fat Globules on the Curd Tension of Cow's Milk