Fermentation of whey to produce a thickening agent

Dairy whey, a waste product of cheese production, is fermented to produce a thickening agent for use in the food industry by forming a fermentation broth containing whey and sucrose, and fermenting the broth with Leuconostoc mesenteroides ATCC 14935. The fermentation broth can optionally contain a water-soluble phosphate as a pH buffer and yeast extract.

BRIEF DESCRIPTION OF THE INVENTION 
The process of this invention provides a method of functionalizing whey by 
forming a fermentation broth of the whey, sucrose and optionally 
water-soluble phosphate as a pH buffer, and yeast extract and then 
fermenting this whey broth with the organism Leuconostoc mesenteroides 
strain ATCC 14935 on deposit with the American Type Culture Collection, 
Rockville, Md. 
BACKGROUND OF THE INVENTION 
Controlled fermentation of food can be used as a means of improving 
functionality of food. Dairy whey, a food, may be an economical source of 
a fermentable substrate, and is widely used as an accepted milk-derived 
ingredient in manufactured foods. If whey can be functionalized by 
fermentation with an organism that produces a thickening polymer when 
grown on the whey substrate, it is possible to obtain whey products that 
may serve the function of a stabilizer, thickener, emulsifier, or flavor 
enhancer. 
Whey is the fluid medium containing a very low concentration of milk solids 
and a high concentration of lactose. Disposal of this waste by-product by 
drying is an energy-intensive, expensive procedure which results in an 
expensive by-product. Sewering of the whey is prohibitive in cost due to 
the high biological oxygen demand which is placed on municipal sewer 
systems. 
The most desirable method of handling a whey waste stream is to produce a 
high quality natural food ingredient from the whey waste product. 
Applicant has discovered a novel method of producing a functionalized whey 
product for use as a food ingredient or any type of product where milk 
solids and lactose are acceptable ingredients.

DETAILED DESCRIPTION OF THE INVENTION 
A functionalized dairy whey product having a viscosity greater than 200 
centipoise at a 12s.sup.-1 shear rate for use as a food ingredient that 
may serve as a stabilizer, thickener, or emulsifier, can be produced by 
fermenting a mixture comprising whey, sucrose, optionally yeast extract 
and a pH buffer with the organism Leuconostoc mesenteroides ATCC 14935 to 
produce a functionalized whey product containing a thickening polymer 
produced by the organism Leuconostoc mesenteroides ATCC 14935. 
Dextrans are polyglugans that are synthesized from sucrose by many species 
of the genera Leuconostoc, Lactobacillus, and Streptococcus. The synthesis 
occurs extracellularly and is catalyzed by a species specific enzyme, 
dextransucrase. Soluble and insoluble dextrans are produced and molecular 
weights range from 1.5.times.10.sup.4 -2.times.10.sup.7 and higher. 
Although dextran has the potential to be used in food products as a 
conditioner, stabilizer, "bodying agent," etc., it has not found wide 
commercial use in the food industry. Dextran has been used in gel 
filtration processes to concentrate proteins or to recover proteins from 
liquid wastes, including cheese whey fractionation. Dextran solutions are 
reported to have properties similar to locust bean gum; see, Brooker, 
1979, "Electron Miscroscopy of Dextrans Produced by Lactic Acid Bacteria," 
Microbial Polysaccharides and Polysaccharases, Berkeley et al. Eds, pp. 
84-115, Academic Press, N.Y.; Jeans, 1977, "Dextrans and Pullulans: 
Industrially Significant D-glucans," Extracellular Microbial 
Polysaccharides, Sanford et al. Eds., pp. 284-298, ACS, Washington, D.C.; 
Kang et al., 1979, "Polysaccharides," Microbial Technology, 2nd Ed., Vol. 
1. pp. 417-481, Academic Press, N.Y.; Lawford et al., 1979, "Dextran 
Biosynthesis and Dextransucrase Production by Continuous Culture of 
Leuconostoc mesenteroides," Biotech. Bioeng. 21:1121-1131; and Wells, 
1977, "Extracellular Microbial Polysaccharides--A Critical Overview," 
Extracellular Microbial Polysaccharides, ACS Symposium Series 45, pp. 
299-313, ACS, Washington, D.C. 
Fermentation of a whey broth comprising unhdyrolyzed whey (acid or sweet), 
sucrose, and optionally yeast extract and phosphate results in polymer 
formation and functionalization of the whey so that the whey product can 
be utilized as a food ingredient. This anaerobic fermentation can be 
carried out preferably in a pH range of 5.5 to 7.5, preferably with the pH 
maintained in a range from about 6.0 to about 7.0. The fermentation can be 
carried out at a temperature from about 20.degree. to 35.degree. C., 
preferably carried out at a temperature from about 25.degree. to about 
30.degree. C. Typical composition of Teklac (sweet dairy whey) is as 
follows: 
______________________________________ 
CHEMICAL AND PHYSICAL SPECIFICATIONS 
______________________________________ 
Ingredient 
Listing: Whey 
Typical Proximate Analysis 
Protein (N .times. 6.38)% 
12.7 
Fat % 1.1 (1.25% Maximum) 
Moisture % 4.5 (5.0% Maximum) 
Ash % 8.0 
Lactose % 71.3 
Calories, Cal/100 g 350.0 
Typical Vitamin & Mineral Analysis 
Vitamin A I.U./100 g Nil 
Vitamin C mg/100 g Nil 
Thiamin mg/100 g 0.40 
Riboflavin mg/100 g 1.76 
Niacin mg/100 g 1.00 
Calcium % 0.71 
Iron % Nil 
Vitamin B.sub.12 ug/100 g 
2.12 
Phosphorus % 0.69 
Pantothenic Acid mg/100 g 
4.09 
Microbiological Standards 
Standard Plate Count 10,000/g (Maximum) 
Coliforms 9/g (Maximum) 
E. coli Negative 
Salmonella Negative 
______________________________________ 
The nutritional values listed above are within 80% of the value declared in 
compliance with Federal Nutritional Regulations 21 CFR .sctn.1.17(4)(ii). 
______________________________________ 
Typical Range 
Limit 
______________________________________ 
Solubility Index 0.1-0.5 ml 1.25 ml Max. 
Acidity 0.10-0.14% 0.16 Max. 
Alkalinity of Ash 175-200 ml 225 ml Max. 
Scorched Particles 
7.5 mg 15.0 mg Max. 
Particle size (Through 40 Mesh) 
99-100% 98% Min. 
______________________________________ 
Concentration of whey can range from about 0.5% to about 12.0%, preferably 
from about 1% to about 3%, and the concentration of added sucrose can 
range from about 5.0% to about 20.0%, preferably 8% to 12%. The 
concentration of the optional yeast extract in the fermentation broth can 
range from about 0 to about 0.5%, preferably from about 0.01% to about 
0.05%. Concentration of optional phosphate can range from 0 to about 0.25% 
K.sub.2 HPO.sub.4 as desired. Adequate fermentation broth viscosities 
(&gt;200 cps and preferably &gt;800 cps at a 12 s.sup.-1 shear rate) are usually 
reached within 30 to 50 hours. All of the above weight percents are in 
weight per volume. 
EXAMPLE 1 
FIG I shows a typical fermentation of a whey-sucrose broth medium 
containing 4% Teklac, 10% sucrose, 0.1% K.sub.2 HPO.sub.4 and 0.05% yeast 
extract that has been fermented with Leuconostoc mesenteroides ATCC 14935. 
The medium was sterilized by autoclaving at 15 pounds per square inch 
(psi) for 20 minutes. The sucrose was sterilized and added separately. The 
pH was adjusted to 7.0 before autoclaving. NH.sub.4 OH (6%) was used to 
prevent the pH from falling below 6.0. The fermentation was anaerobic (no 
gas sparged), with agitation speed 120 rpm. The temperature was maintained 
between 25.degree.-27.degree. C. The inoculum was a 20-hour-old culture 
grown in 10% sucrose, 0.5% K.sub.2 HPO.sub.4, 0.25% yeast extract, and 
0.01% MgSO.sub.4. A Bio-flow.RTM. fermentor was used (New Brunswick 
Scientific Co., N.J.). The figure shows that within 46 hours, a viscosity 
greater than 500 cps (at a 12s.sup.-1 shear rate) was observed. More than 
95% of the sucrose was utilized and 40% of the lactose was consumed. 
EXAMPLE 2 
FIG. II shows a typical fermentation of a whey-sucrose medium containing 4% 
Teklac, 10% sucrose, and 0.05% yeast extract. The medium was sterlized by 
autoclaving at 15 psi for 20 minutes. The sucrose was sterilized and added 
separately. The pH was adjusted to 7.0 before autoclaving. NH.sub.4 OH 
(6%) was used to prevent the pH from falling below 6.0. The fermentation 
was anaerobic (no gas sparged), with agitation speed 120 rpm. The 
temperature was maintained between 25.degree.-27.degree. C. The inoculum 
was a 20-hour-old culture grown in 10% sucrose, 0.5% K.sub.2 HPO.sub.4, 
0.25% yeast extract, and 0.01% MgSO.sub.4. A Bio-flow.RTM. fermentor was 
used as in Example 1. The figure shows that within 46 ours, a viscosity of 
460 cps was obtained. About 95% of the sucrose was utilized and 44% of the 
lactose was consumed. 
The high viscosity broths produced by fermentation techniques of this 
invention may be dried and/or sterilized by autoclaving plus 
lyophilization, spray drying, or other techniques. 
EXAMPLE 3 
A viscosity versus shear rate curve for a typical dried functionalized whey 
so produced is shown in FIG. III. The sample was tested on a 2.5 XLVT 
Wells-Brookfield microviscometer having a 3.degree. cone at 25.degree. C. 
The sample size was 2.0 milliliters. The sample consisted of a 10.0% 
solution (weight/vol) of functionalized whey in deionized water. The pH 
was 6.9. The increase in viscosity with decrease in shear rate is typical 
of pseudoplastic polymers. 
The functionalized whey product of this invention can be used as a food 
ingredient where milk solids and/or whey, and/or thickeners, and/or 
stabilizers are used such as in ice cream, salad dressing, foam 
stabilizers (meringue), puddings, snack foods, etc.