GB2147188A - Low calorie, low fat fruit-containing yogurt product and method for making same - Google Patents

Abstract

The yogurt product having a fat content less than 0.2% by weight and a carbohydrate content of less than 0.5% by weight is prepared by admixing pasteurized skim milk, having a fat content of less than 0.2% by weight, with heat modified nonfat dry milk solids, and suitable stabilizers; heating the mixture to 190 DEG to 195 DEG F. (87.7 to 90.6 DEG C.) for 20 to 60 minutes; adding optional heat labile vitamins; homogenizing the mixture at 1000 to 2000 psig (70.03-140.06 kg/cm<2>); cooling the homogenized mixture to 110 DEG F. (43.3 DEG C.); and innoculating with a blend of standard yogurt cultures. If a Swiss style yogurt is to be produced, the innoculated mixture is cooled, pumped through a pressure valve to obtain a smooth texture, blended with low calorie fruit preserves, packaged and refrigerated to stop fermentation. If a Western style yogurt is to be produced, the innoculated mixture is added into individual yogurt containers containing low calorie fruit preserves and cooled to stop fermentation. The low calorie fruit preserves comprise 40 to 50% by weight fruit in an invert sugar syrup containing at least 36% by weight fructose.

Description

SPECIFICATION Low calorie, low fat fruit-containing yogurt product and method for making same The present invention relates generally to a method for making a fruit-containing yogurt product having the appearance, texture and taste of conventional custard-type fruit-containing yogurt and, more specifically, to a method for making a fruit containing yogurt product having a fat, carbohydrate and calorie content significantly below that of conventional fruitcontaining yogurt.

In recent years cultured milk products, referred to as yogurt, have enjoyed immense popularity. The beneficial effects on health due to the therapeutic properties of the bacterial cultures contained in yogurt are well known. In addition, yogurt has become a popularfood among dieters. To increase its appeal, the sharp, tangy taste characteristics of plain, unflavoured yogurt, which heretofore madeyogurtunacceptable to many people, has been masked in many yogurt products with fruit and sweeteners. This practice has resulted in a flavoured yogurt product that is more palatable to a wider segment ofthe population.However, the use of these additives has been accompanied by an increase in product calorie contentfrom about 90 calories per eight ounce (224 grams) serving of plain, unflavored yogurtto about 250to 270 calories per eight ounce (224 grams) serving of the sweetened, fruit-containing yogurt. Such a high calorie content renders the fruited product generally unsuitable for inclusion in reducing diets since the fruit yogurt uses up the majority of the calories usually allotedto a single meal. As a resultthe dieter has difficulty choosing a sufficientvariety or quantity of foods to form a balanced meal within the remaining calories allowed. Accordingly, a need has developed for a fruit-containing yogurt product which is low in calories, fat and carbohydrate content.

Prior methods for producing sweetened or flavored yogurt have succeeded in obtaining a product with a relatively low butterfat content, for example, as low as the O.5% butterfat content of ordinary skim milk, but none seem to have been able to produce a really low fat, less than about 0.5%, yogurt product having the characteristic creamy custard-type yogurt consistency while atthe sametime overcoming the high calorie and high carbohydrate problems accompanying the use of fruited orflavored yogurt. One reason forthis is that yogurt previously made from really low fat milk products, less than about 0.5% butterfat, has been loose and watery and lackinginflavorratherthan creamy and custard-like with consumer acceptable flavor, appearance and mouth feel.Efforts to overcomethis problem to obtain a palatable product have either required adding flavor influencing milk solids, which increases the yogurt calorie content, or increasing the milkfat content, which has a similar effect.

Exemplary of prior methodsfor producing flavored yogurt is U.S. Patent No. 3,969,534 to Pavey et al which teaches the production of a fruited, flavored yogurt which has a relatively low, about 0.5%, butterfat content. However, the product produced by the Pavey method does not appearto be low in carbohydrates or significantly lower in calories than conventional flavored yogurt. In U.S. Patent No.3,025,165, Metzger discloses a process for producing yogurt which uses relatively low butterfat starting materials, such as skim milk, to which is added about 1.5% to 6.4% of an unsaturated vegetable oil. As a result, a hig her than desirable fat contentfor a reducing diet is obtained without significantly reducing the numberof calories.

Likewise, the fruited yogurt product produced by the process disclosed in U.S. Patent No.3,269,842 to Mayeretal has a fat content of about 4% and appears to be a high calorie, high carbohydrate product. Donay et al in U.S. Patnet No.3,128,190, disclose the use of a skim milk starting material. However, the process for making Donay's fruit-containing yogurt requires fruit which is precooked with sucrose to preventfermentation thereof by the yogurt cultures with resultant unpleasant flavors. As a result ofthis procedure the Donayetal method neither produces really lowfat yogurt nor reduces the high calorie and carbohydrate content offruit-containing yogurt. In U.S. Patent No.

4,110,476, Rhodes discloses a process for preparing liquid, rather than custard-type, yogurt products which utilize whey protein concentrate together with milk products as the starting material ingredients and contain highersugar contents than are desirable for a fruit-containing yogurt product suitable for a reducing diet.

In one aspect of the present invention there is provided a fruit-containing yogurt product which resembles conventional yogurt in appearance, texture and taste, but which has a fat, carbohydrate and calorie content significantly below that of known custard-type yogurt products.

In still another aspect ofthe present invention there is provided a fruit-contai ni ng, custa rd-type yog u rt which is nutritionally equivalent to an average serving of milk and fruit, but is sufficently low in fat, carbohydrate and calories to be included as a desirable component of a reducing diet.

In yet another aspect ofthe present invention there is provided a nutritious, palatable, fruit-containing yogurtproductwhich has the creamy mouth feel and the sweet, fruity, slightly tangy taste of conventional custard-type yogurt but which has a fat content below about 0.2% byweightofthefinal product and a carbohydrate content below about 1 % by weight of the final product.

In still another aspect ofthe present invention there is provided a method for making a very lowfat, low carbodhydrate, low calorie fruit-containing, custardtype yogurt product.

In accordance with the aforesaid objectives, the present invention provides a process for making a low fat, low carbohydrate, low calorie, fruit-containing, custard-type yogurt product resembling conventional fruit-containing yogurt in appearance, texture and taste which includes the steps of admixing pasteurized skim milk having a fat content of less than about 0.2%, preferably less than about 0.1 %,with suitable stabilizers and specially heat modified nonfat dry milk solids; adding optional vitamin and mineral fortifica tion,sweeteners,flavorants andlorcolorants; heating the resulting mixture with constant agitation to about 190 to 195 F. (87.7 to 90.6"C.)for about 20to 60 minutes; adding optional heat labile vitamins, such as Vitamin C; and homogenizing the mixture under conventional elevated pressure conditions at 500 to 5000 psig (35.15 to 351.5 kg/cm2), desirably 1000 to 2000 psig (70.30 to 140.06 kg/cm2) and preferably at 1200 to 1500 psig (84.36to 105.45 kg/cm2).The homogenized mixture is cooled to about90to 120 F.

(32.2 to 48.9"C.), preferably 1 10'F. (43.3"C.), and innoculated with a uniquely proportioned blend of standard yogurt cultures.

It it is desired to produce a Swiss style yogurt which has pieces of fruit homogeneously mixed thro ughout anda predominantlyfruityflavor,theinnoculated mixture is maintained at this temperature until the desired taste and custard body are achieved, which is usually at a pH of about4.5 to 4.7. The yogurt is then cooled to about 50, to 75"F. (10 to 23.90C), preferably 65'to 700F. (18.3to 21 .10C.), and pumped through a small orifice, such as a screw or pressure valve, to break up small pieces of coagulant which are present and to produce a smooth, continuous mass, all as is well known in the art.Low calorie, low carbohydrate fruit preserves arethoroughlyblended into the custard, and the resulting product is packaged in suitable individual containers and refrigerated at temperatures sufficiently low to stop fermentation, generally 35 to 50"F. (1.6 to 1 0'C). The resulting low calorie, low carbohydrate, low fat product, which resembles conventional Swiss type yogurtwith its smooth, creamytexture and slightlytangyfruity flavor, contains pieces of fru it suspended throughout.

If it is desired to produceWestern styleyogurt in which a deep layer of plain orunflavoredyogurt custard covers a shallow layer offruit preserves, the innoculated milk-stabilizer-milk solids-vitamin-flavor- ant mixture is pumped into individual containers, such as conventional 8ounce (224 gram) yogurtcontainers to which has already been added 1.0 ounce (28 grams) of low caloriefruit preserves.The containers are then maintained at about 110"F. (43.3"C.) until the desired taste and custard body has been achieved, which is usually when the pH of the yogurt is about 4.5 to 4.7, and are then cooled to a temperature sufficiently low to stop fermentation, generally 35 to 500F. (1.6 to 10"C.), preferably to conventional refrigeration temperatures, until ready for sale. The resulting low calorie, lowfat product has a smooth, creamy custard texture and, unless sweeteners have been added, a typical tartyogu rt taste which becomes sweet and predominantly fruity only when the preserves at the bottom are stirred into the yogurt custard.

The low calorie, low fat custard-type fruit-containing yogurt product of the present invention comprises a major amount of pasteurized, homogenized cultured skim milk and minor amounts of low calorie fruit preserves, stabilizers, vitamins, minerals and flavorants. Mostimportantly,the productofthe present invention has a total fat content by weight of less than about 0.2%, preferably less than about 0.1%, a total carbohydrate content by weight of less than about 1 %, preferably about O.4%, and contributes only about 150 calories per eight ounce (224 gram) serving to the diet.

Desirably,the product has a pH in the range 4.3 to 4.6, a total solids content of about 19%, and contains about 15% to 20% byweightfruit.

The present invention relates broadly to a lowfat fruit-containing yogurt product which resembles con- ventional custard-typefruit-containing yogurt in appearance, texture and taste, but which has fat, calorie and carbohydrate contents substantially reduced belowthose of conventional yogurt. As a result, the yogurt made by the methodofthe present invention is suitable for inclusion in the diets of persons for whom a reduced intake offat, carbohydrates or calories is necessary or desirable.

The process by which the fruit-containing yogurt product ofthe present invention is made involves admixing pasteurized skim milk, stabilizers and step cially heat modified nonfat dry milk soilids; adding vitamins and minerals, sweeteners, flavorants andlor colorants to the admixture; heating the resulting mixture to a temperature of about 190 F.to 1950F.

(87.7 to 90.6"C); adding optional heat liable vitamins, such as Vitamin C; and homogenizing the resulting mixture by conventional homogenization means. The homogenized mixture is then cooled to a temperature of about 90 to 120"F. (32.2 to 48.9"C), preferably 11 00F.

(43.3"C) and innoculated with a uniquely proportioned blend of standard lactic acid producing yogurt cul- tures. Depending on whether a Swiss type or a Western style yogu rt is desired, the innoculated mixture is maintained at this temperature in the bulk mixing vat until the desired taste and texture are achieved, then cooled to about 50" to 75"F. (10 to 23.9"C.), pumped through a screw or pressure valve and admixed with fruit preserves priorto packaging and refrigeration (Swiss style) or placed in conventional yogurt containers to which fruit has already been added and maintained at about 1 100F. (43.3 C.) while in the containers until the product has achieved an acceptable taste and texture before being cooled at conventional refrigeration temperatures (Western style).

In orderto prepare a yogurt product having a fat content notgreaterthan about 0.2% by weight the use offat contributing ingredients must be carefully controlled. Inasmuch asthe primaryfatcontributing ingredient in yogurt is generally milk, a low fat content maybe achieved by selecting a skim milkwitha butterfat content of less than about 0.2% by weight, and preferably less than about 0.1 % by weight, for use in the process of the present invention. The term "milk" as used herein means the conventional milk of commerce (butterfatcontent ranging from about O.1 % to 7% by weight) as well as equivalent compositions formed by suitable admixtures of milk solids and water.

The primary carbohydrate contributing ingredients in yogurt are sugars, which may be added to the yogurt custard to flavor it or, more typically, are added in the preparation ofthefruit component. Typically, the fruit added to yogurt resemblesfruit preserves having discrete pieces offruit or whole berries in a thickened sugar syrup. Fruit in this form effectively maskstheflavoroftheyogurtwith a predominantly sweet, fruity taste and is less likely to be fermented by the yogurt bacteria. To prepareafruit-containing yogurt having a carbohydrate content of less than about 1 by weight, the amount of sugar added to the yogurt custard or used in the preparation of the fruit must be carefully regulated.In the past, this has presented a problem since use of less than about 1 % by weight of the final product of sucrose, the sugar form most commonly used to prepare fruit for use in yogurt products, does not result in a sufficiently sweet product.

The e process of the present invention achieves a low carbohydrate fruit containing yogurt product by utilizing fruit which has been prepared to resemble the preserves heretofore used in conventional yogurt, but which have been prepared with monosaccharide sugars having high sweetening effects, instead of sucrose. Forexample,the use of fructose, a monosaccharide with a sweetening effect substantially greater than that of sucrose, to form the syrup results in fruit preserves which are as sweet as those prepared with sucrose but which have a substantially lower carbohydrate level.A preferred fruit preserve preparation which has been found to achieve the desired results contains 40% to 50% by weightfruit pieces or whole berries cooked in a syrup made from invert sugar containing at least 36% fructose thickened with pectin.

The resulting preserves contain about 41% to 47% solids, are at the normal pH forthe specific fruit used, and contain not more than 825 calories per pound (about 1817 calories per kg) of preserves. Any ofthe fruits and berries commonly used in conventional fruit-containing yogurt products, such as strawberries, blueberries, cherries and the like, may be prepared for use in the product ofthe present invention. The combination of a low level of carbohydrates and a low level offat results in a yogurt product havingsignificantlyfewercaloriesthan prior products.

To prepare the low calorie fruit-containing yogurt of the present invention pasteurized skim milk having a fat content of less than about 0.2% by weight, preferably less than about 0.1 % by weight is placed in a stainless steel mixing vat orthe like container. The skim milk may have been pasteurized by any conventional means, although it is preferred to use skim milk which has been pasteurized by the high temperture, shorttime (HTST) method. To the skim milk are added stabilizers and nonfat dry milk solids. A preferred combination of stabilizers which has been found to be successful contains agar, pectin, guar gum and gelatin. However, other commonly used commercially available dairy stabilizers could also be utilized, either alone orion combination.The stabilizer or combination of stabilizers comprise less than about 1.0%, preferably about 0.7%, by weight ofthefinal product. The nonfat dry milk solids comprise up to about 2%, preferably about 1.2%, by weight ofthe final product. In order to achieve the low fat, low carbohydrate and low calorie levels of the yogurt of the present invention yet prepare a custard-type product having a creamy consumer acceptable appearance and mouth feel ratherthan the loose and watery consistency of previously attempted low fat yogrt products,the dry milk solids should be of the heatmodifiedtype.Such a modified milk solids product is commercially available from a number of manufacturers.Exemplary of suitable products are "PMC" available from Pro-Mark Co. of Tulsa, Oklahoma, "Hi-Sorb" available from MPI Division of Stauffer Chemical Company, Inc. and "Crest Lac" available from Crest Foods Co., Inc. of Ashton, Illinois. Each of these products is a grade-A conventional nonfat dry milk product which has been modified primarily by heat for the purpose of increasing the hydration of the protein and for making the product more effective in transmitting texture and flavor. See, for example, U.S.

Patent No.4,096,287 for a discussion of acceptable methods for preparing the nonfat dry milk product including the essential step of non-coagulative direct steam heating of condensed skim milk priorto spray drying for modifying the milk protein. It has been found convenient to premix the stabilizers and nonfat dry milk solids in the amounts normally used for production so that the nonfat dry milksolids serve as a carrierforthe stabilizers. In this connection, as previously indicated, it is acceptable to use admixtures of nonfat dry milk solids and water in lieu of the skim milk in the process of the present invention.If this is done, preparation of the milk starting ingredient must beconsistentwith the desired 17to 20% by weight, preferably about 19% byweight, total solids in the final product.

It is desirable to fortify the fruit-containing yogurt product of the present invention with vitamins and minerals so that an eight ounce (224 gram) serving is nutritionally equivalentto a single serving of milk, which is usually eight ounces (224 gram), and a single serving offruit, which varies according to the kind of fruit. Such fortification, while not essential to the present invention, results in a product of greater nutritional value than a nonfortified product and facilitates the intake of the recommended daily allowances of these vitamins and minerals. Heat labile vitamins and minerals, such as Vitamin C which is destroyed by prolonged high temperatures, should not be added at this stage of the process, but are preferably added at a later time after high temperature heating hastaken place.

Atthis stage in the process, particularly if the end product isto be a Western style yogurt in which the fruit is on the bottom, it may be desirable to add a sweetener, flavor enhancer or colorant. Addition of one or any combination ofthese ingredient materials produces a yogurt custard that is sweet, flavored and/or colored withoutthe fruit being stirred therethrough. Any sweetener used must not, in combination with the sweetened fruit, exceed the required carbohydrate level limitation of less than 1 % by weight of the product. It is preferred, therefore, to use as the added sweetenerfructose or a similar high sweetening monosaccharide. Any one of a number of commercially available and well known flavor enhancers and/or certified food grade colorings may also be used.

The skim milk-stabilizer-nonfat dry milk solids mixture, which may contain vitamins, minerals, sweeteners, flavorants and/or colorants is heated to a temperature in the range from about 190"to 195"F.

(87.7 to 90.6 C.) for a time sufficient to form a uniform, substantially homogeneous mixture and to pasteurize the mixture, usuallyabout20-60 minutes. Heat treating atthis high temperature denatures the milk protein, causing water in the mixture to be absorbed and helps to create a thicker, richer product having a custard-type body and texture. The heat labile vita mins and minerals, such as Vitamin C, may be added once the heat treatment at 190-195"F. (87.7 to 90.6 C.) is complete and the mixture has cooled belowthe temperature atwhich the particular vitamin and/or mineral might be adversely affected.The mixture is then homogenized by conventional homogenization means at about 500-5000 psig (35.15 to 351.5kg/cm2), desirably 1000 to 2000 psig (84.36 to 105.45 kg/cm2), afterwhich it is cooled to an optimum culturing temperature, generally in the range 90to 120 F. (32.2 to 48.9 C.) and preferably about 110"F. (43.3"C) in preparation for bacterial innoculation, although the temperature mayvaryslightly according to the bacterial culture or cultures used.

The pasteurized, homogenized mixture is innoculated with a uniquely proportioned blend of lactic acid producing bacterial cultures commonly used in yogurt production in orderto confer upon the final yogurt productthe proper combination of acidity, tartness and body appropriate for a custard-type yogurt product. Preferred as constituents of the customized yogurtcultureforuse in the process ofthe present invention are Lactobacillus bulgaricus, Streptococcus thermophilusand Lactobacillus acidophilus.It has been found thatwhen all three ofthese bacterial cultures are simultaneously employed in predetermined proportions, even very lowfat milk-containing mixtures can be cultured to achieve the important custard-type creamy body and mouth feel of conventional yogurtwhile, atthe same time, achieving the desired tartness and acidity.This cannot be successfully achieved with otherthan all three bacterial cultures employed in thefollowing proportions by weight: Lactobacillus acidophilus 30-50% Lactobacillus bulgaricus 25-35% Streptococcus thermophllus 25-35% The proper combination ofcultures is generally determined by the amount of Lactobacillusacidophilus required to culture the lowfat milk mixture to a stringy, rubbery bodytexture which will yield an acceptable custard-type creamy mouth feel. The Lactobacillus bulgaricus and Streptococcus thermo phlluscomprisethe balance of the culture in about equal proportions.

To this pointin the processthere is no significant difference in processing between the preparation of Swiss style yogurt, which has a predominantly fruity flavor and contains pieces of fruit uniformly dispersed throughoutthe yogurtcustard, and the preparation of Western style yogurt, which has a shallow layer of fruit preserves on the bottom of the yogurt container covered buy a deep Iayerofyogurtcustard. The primary difference in processing the two types is that the Swiss style is cultured in the bulk mixing vat before packaging while the Western style is cultured in the individual containers in which it is packaged.

If a Swiss style yogurt is desired, the cultured mixture is maintained at about 110"F. (43.3"C.) until a yogurt custard with an acceptable body and taste is produced. Although taste and texture are highly subjective andwill vary from producertoproducer, experience has shown that when the product reaches a pH in the range of about 3.8 to 4.8, preferably about 4.5 to 4.7, which typicallytakes abouttwo to four hours, an acceptablyfirm yogurtcustardwith a pleasantly sharp, tangy taste has been produced.

When an acceptable productfrom the standpoint of taste and texture has been produced, the yogurt is cooled to about 50 to 75 F. (10 to 23.9C.), preferably about 65" to 700F. (18.3 to 21.1 C. }, to slow the fermentation while maintaining a sufficientlyfluid mixture so that it can be readily pumped through a screw or pressure valve. The cooled mixture is then pumped through a screw or pressure valve to achieve a smooth texture. Fruit preserves prepared with high sweetening monosaccharides, preferably fructose, arethoroughly blended into the yogurt custard, preferably at a level of about 15% to 20% by weight fruit in the final product.The resulting product is packaged in conventional yogurt containers and held at conventional refrigeration temperatures, preferably about 35 to 40 F. (1.6 to 4.4"C.), to fully terminate fermentation. When maintained under conventional refrigeration temperatures, the product has a shelf life of about 30 days.

If a Western style yogurt is desired, about one ounce (28 grams) of fruit preserves prepared with high sweetening monosaccharides, preferably fructose, is placed in the bottom of conventional eight ounce (224 gram) yogurt containers. On top ofthis is added about seven ounces (196 grams) ofthe culture-containing, pasteurized, homogenized mixture. The fruit comprises preferably about 15% to 20% byweightofthefinal product. Thefilled containers are maintained at about 110 F. (43.3"C.) until an acceptable taste and texture are produced in the yogurt custard.If a sweetener has been added to the yogurtmixturethis may affect somewhat the perception of when an acceptable yogurttaste has been achieved. However, as with the Swiss style yogurt, the notion of what constitutes a suitable product is likelyto vary, with acceptable results generally reached when the pH ofthe product is about 3.8 to 4.8, preferably 4.5 to 4.7. This pH level is generally reached in a bout two to four hours. The containers are thereafter cooled to and maintained at conventional refrigeration temperatures to stop the fermentation, preferably 35" to 40"F. (1.6 to 4.4"C.).

Underthese conditions, the product has a shelf life of about 30 days.

Thefollowing examples illustrate the practice of the present invention and are intended to exemplify and to limit in any respectthe content and scope thereof.

Example I A low calorie, lowfat Swiss style yogurt was prepared in the following manner: 2125 pounds (964.75 kg) of HTST pasturized skim milk (less than 0.2% by weight butterfat) was placed in a stainless steel culturing vat equipped with an agitator. To this milk was added 40 pounds (18.16keg) of a premixed stabilizer-nonfat dry milk mixturewhich contained about8 pounds (3.63 kg) of a mixture of agar, pectin, guargum and gelatin and about 32 pounds (14.53 kg) of"PMC" brand heat modified nonfat dry milk solids, and a mixture of vitamins (except Vitamin C) and minerals in quantities which, in the final product, would bethe nutritional equivalent to those contained in an 8 ounce (224 gram) serving of milk and an average serving offruit The resulting mixture was thoroughly blended and vat pasteurized at 190" to 195 F. (87.7 to 90.6"C.) for 30 minutes.

Vitamin C was added and the mixture was homogenized at 1500 psig (105.45 kg/cm2). The homogenized mixture was then cooled to about 1 10'F. (43.3"C.), innoculated with mixture, by weight, of 40% Lactobacillusacidophilius, 30% Lactobacillus bulgaricus and 30% Streptococcus thermophilus cultures and maintained in the vat atthis temperature until the mixture reached a pH of about 3.8 to 4.8 and had an acceptable custard consistency. The yogurt was cooled to about 65" to 70"F. (18.3two 21.1"C.) and then pumped through a pressure valve to give it a smoother texture. Five hundred pounds (227 kg) of blueberry preserves having less than 825 calories per pound (1817 calories per kg) were mixed into the yogurt custard.The blueberry preserves contained 40% to 50% by weight whole blueberries in a syrup made from invert sugar containing at least 36% to 38% fructose to which pectin had been added to thicken it. The resulting low calorie, low carbohydrate, low fat yogurt had a smooth, creamy texture, contained blueberries uniformly mixed throughout, was the color of blueberries mixed with cream and had a predominantly sweet blueberrytaste in combination with a slightly sharp and tangyyogurttaste. The product was packaged in conventional eight ounce yogurt cups, contained 150 calories, 0.2% by weight fat, 0.4% by weight carbohy drate, 4% by weight protein and 19% byweightsolids per eight ounce (224 gram) serving, and remained stable for about 30 days at 35" to 40 F. (1.6 to 4.4"C.).

Example II A low calorie, low fat Western style yogurt was prepared in the following manner: 2202 pounds (999.7 kg) of HTST pasteurized skim milk (less than 0.2% byweight butterfat) was placed in a stainless steel vat equipped with an agitator. To this milkwas added 93 pounds (42.22 kg) of invert sugar which contained 36% to 38% fructose, minor amounts offlavorenhancers and certified color, 40 pounds (18.16kg) ofthe same premixed stabilizer-nonfat dry milk additive used in Example land a substantially identical mixture ofvitamins and minerals as in Example I.The resulting mixture was thoroughly blended and vat pasteurized to 190"to 195"F. (87.7 to 90.6'C.)for30 minutes. Vitamin Cwasthenadded and the mixture was homogenized at 1500 psig (105.45 kg/cm2). The homogenized mixture was cooled to about 110"F. (43.3"C.) and innoculated with a mixture, by weight of 40% Lactobacillus acidophilus, 30% Lactobacillus bulgaricus and 30% Streptococcus thermophiluscultures. 335 pounds (152.09keg) of blueberry preserves in an invert sugar syrup was prepared as described in Example land one ounce (7-8 grams) of these preserves was pumped into each of a number of conventional eight ounce (224 gram) yogurt cups. The cups were then filled with the innoculated 11 0'F.

(433C.) homogenized mixture and maintained at 110of. (43.3"C.) until the yogurt reached a pH of about 3.8to 4.8 and had an acceptable custard consistency.

The cups were cooled to 35" to 40"F. (1.6 to 4.4 C.), at which temperature the product remained stable for about 30 days. The resulting low calorie, low carbohydrate, lowfatyogurt had a smooth, creamy texture which had a slightly sweet, predominantly sharp yogurttaste before the preserves were stirred up from the bottom. This yogurt looked and tasted like the Swiss style and had the same calorie, fat, carbohydrate, protein and solids content.

Claims (10)

1. A method for making a less than 1% by weight total carbohydrate, less than about 0.2% by weight fat, low calorieyogurt product containing fruit in an amount from 1 5 to 20% by weight of the yogurt product, said method comprising the steps of:: (a) admixing pasteurized skim milkhavingafat content of less than about 0.2% by weight, stabilizers and an amount of nonfat dry milk solids effective to improve texture and flavor, said nonfat dry milk solids being derived from a process in which condensed skim milk is subjected to non-coagulative direct steam heating priortospraydrying; (b) heating said mixtureto a temperature in the range from about 190" to 195"F (87.7 to 90.6 C.) for a time sufficientto form a uniform, substantially homogeneous mixture and to effect pasteurization; (c) homogenizing said pasteurized mixture at pressures in the range 500 to 5000 psig (35.15to 351.5 kg/cm2);; (d) cooling said homogenized mixture to a temperature of about 90 to 120 F. (32.2 to 48.9DC.); (e) innoculating said cooled homogenized mixture with a lactic acid producing bacterial yogurt culture mixture consisting essentially of, by weight, 30-50% Lactobaclllus acidophllus, balance Lactobaclllus bul- garicus and Streptococcus thermophilus in approximately equal proportions;; (f) maintaining said innoculated mixture art a temperature of about 90 to 120 F. (32.3 to 48.9 C.) for a timesufficientto product a pH in the range of about 3.8 to 4.8 and to form an acceptable taste and texture in said innoculated mixture; (g) cooling said innoculated mixture to atemperature in the range 50to 75"F. (10 to 23.9'C.); (h) forming said cooled innoculated mixture into a smooth textured product;; (i) blending said smooth textured product with low claorie fruit preserves, said low calorie fruit preserves comprising about40% to 50% by weight of fruit and a syrup for said fruit, said syrup including invert sugar containing at least 36% by weight fructose, said low calorie fruit preserves containing not more than 825 calories per pound (1817 calories per kilogram) thereof; and (j) cooling said blend of fruit preserves and smooth textured product to a temperature sufficiently low to stop fermentation.

2. A method for making a lessthan 1% by weight total carbohydrate, less than about 0.2% byweightfat, low calorie yogurt product containing fruit in an amountfrom 15to 20% by weight ofthe yogurt product, said method comprising the steps of:: (a) admixing pasteurized skim milk having a fat content of less than about 0.2% by weight, stabilizers and an amount of nonfat dry milk solids effective to improve texture and flavor, said nonfat dry milk solids being derived from a process in which condensed skim milk is subjected to non-coagulative direct steam heating priorto spray drying; (b) heating said mixture to a temperature in the range from about 190 to 195"F. (87.7 to 90.6"C.) for a time sufficientto form a uniform, substantially homogeneous mixture and to effect pasteurization; (c) homogenizing said pasteurized mixture at pressures in the range 500 to 5000 psig (35.15 to 351.5 kg/cm2);; (d) cooling said homogenized mixture to a temperature of about 90 to 120"F (32.2 to 48.9 C.); (e) innoculating said cooled, homogenized mixture with a lactic acid producing bacterial yogurt culture mixture consisting essentially of, by weight, 30-50% Lactobacillus acidophilus, balance Lactobacillus bulgaricus and Streptococcus thermophilus in approx imatelyequal proportions;; (f) adding said innoculated mixture into individual yogurt containers containing low calorie fruit preserves, said low calorie fruit preserves comprising about 40% to 50% by weight offruit and a syrup for said fruit, said syrup including invert sugar containing at least 36% byweightfructose, said low calorie fruit preserves containing not more than 825 calories per pound (1817 calories per kilogram) thereof; (g) maintaining said fruit preserves and innoculated mixture at a temperature ofabout 90 to 1 20"F.

(32.2 to 48.9'C.) for a time sufficientto produce a pH in the range of about 3.8 to 4.8 to form an acceptable taste and texture in said innoculated mixture; and (h) cooling said fruit preserves and innoculated mixtureto a temperature sufficiently low to stop fermentation.

3. A method, as claimed in claims 1 or 2, wherein said skim milk has a fat content of less than about 0.1% by weight.

4. A method as claimed in claims 1 or2wherein the pH produced in said innoculated mixture is in the range of about4.5 to 4.7.

5. Amethod,as claimed in claims 1 or2,wherein said time sufficient in step (b) is from about 20 to 60 minutes.

6. A method, as claimed in claims 1 or 2, wherein said homogenizing is practiced in the pressure range 1000 to 2000 psig (70.03 to 140.06 kg/cm2).

7. A method, as claimed in claims 1 or2, wherein said temperature sufficiently low to stop fermentation is in the rangefrom 35to about 50"F. (1.6 to 1 0'C).

8. A method, as claimed in claims 1 or2, wherein said temperature sufficiently low to stop fermentation is in the rangefrom 35 to 40"F. (1.6to 4.4"C.).

9. The product of the process of claim 1.

10. Theproductoftheprocessofclaim 2.