For many, a beer with a dense uniform cling not only has great appeal but is also considered satisfactorily balanced in its components. The need for more effective foam stabilizers in the brewing industry has become more apparent in recent years with the increasing use of certain types of hop extracts and chemical pasteurizing compounds.
The latter involves addition of chemical fungicides and bacteriocides to control microbiological growth in finished malt beverage as described, for example, by Strandskov and Bockelmann, U. Both of these processing changes, however, may decrease the natural foam of the finished beer.
Although many materials have been suggested as beer foam stabilizers, commercial success requires a stabilizer that is fully compatible with the complex colloid system of these beverages. An effective stabilizer should not detract from the brilliance of the beverage, impair its cling, or decrease its shelf stability through gradual formation of turbidity and haze or deposition of sediment. Since the composition of the colloidal system differs from batch to batch because of minor variations in raw materials and the brewing process, the stabilizer must itself be uniform in quality and sufficiently active to compensate for normal product variations.
The general concept of using cellulose derivatives as foam stabilizers for aqueous systems is old. For example, Frieden U. Advantages of hydroxypropyl methyl cellulose ether beer foam stabilizers are described in Weaver and Greminger, U. Shaler and McAdam, U. Yet in practice, despite repeated trials no brewery has been able to use a cellulose ether as a foam stabilizer on a regular production basis.
Inconsistent performance and erratic side effects have prevented general commercial use. The cellulose derivatives that have been tried lack the requisite balance of physical and chemical properties necessary for both improved foam stability and consistent compatibility. Furthermore these particular cellulose ethers not only readily disperse in the malt beverages under normal processing conditions, but also they are compatible with and effective in combination with chemical pasteurizing agents such as n-heptyl p-hydroxybenzoate and octyl gallate.
More specifically, this invention is a process for preparing a carbonated malt beverage with improved foam characteristics resulting from the addition of a water-soluble C3 -C4 hydroxyalkyl carboxymethyl cellulose having a C3 -C4 hydroxyalkyl MS of at least about 1.
Preferably the cellulose foam stabilizer is a hydroxypropyl carboxymethyl cellulose with a hydroxypropyl MS of about 1. The resulting treated beverages have demonstrated increased foam stability and cling as well as desired liquid clarity in tests with many batch and brand variations in beer composition.
The process is particularly suited for improving the foam of unpasteurized beers containing a chemical pasteurizing agent to control microbiological growth. The term "beer" is used to encompass all such carbonated malt beverages. The compatibility of the improved foam stabilizers with the complex aqueous beer colloid system depends on the specific substitution of the cellulose ether.
Thus the suitable ethers have a C3 -C4 hydoxyalkyl molar substitution MS of at least about 1. Preferred are hydroxypropyl carboxymethyl cellulose ethers with a hydroxypropyl MS of about 1. Such hydroxyalkyl carboxymethyl cellulose ethers are prepared by standard methods. Thus they can be prepared by propylene oxide or butylene oxide hydroxyalkylation of a carboxymethyl cellulose having the requisite carboxymethyl DS.
Alternately, finely divided alkali cellulose can be reacted in one stage with a mixture of sodium chloroacetate or chloroacetic acid and a C3 -C4 alkylene oxide, or in a separate two stage reaction. The organic diluent slurry process of Klug, U. Optimum results are obtained with a fairly uniform distribution of the substituent hydroxyalkyl and carboxymethyl groups in the cellulose ether.
The molecular weight of the cellulose ether as shown by the standard 2 percent aqueous solution viscosity at pH 7. At the low concentrations required, the cellulose ethers readily disperse in the beer without significant effect on its processability. Some improvement is noticeable at concentrations as low as 5 ppm. Concentrations higher than ppm can be used, but the benefits are not commensurate with the added cost. The point of addition of the cellulose ether foam stabilizer after fermentation is not critical.
However, it is preferably added as an aqueous solution during the final processing before customer packaging. For example, it can be injected into the beer transfer line after primary filtration, after the finish stage but before final filtration, or after final filtration depending on the process requirement of a particular plant.
Until recently, packaged beer was generally heat pasteurized to prevent microbiological growth. However, chemical pasteurizing agents are now being used by many brewers to control the bacteria and fungi during storage prior to consumption. Tests with two commercial bacteriocides, n-heptyl p-hydroxybenzoate and octyl gallate, indicate that the improved cellulose ether stabilizers described herein enhance the foam properties of beers containing such antimicrobial agents and are fully compatible in other properties.
Indeed it has been found that use of these hydroxyalkyl carboxymethyl cellulose ethers also improves the chill haze stability of beer treated with n-heptyl p-hydroxybenzoate. The following examples illustrate further the present invention and its advantages.
Unless otherwise specified all parts and percentages are by weight. To an alkali cellulose slurry prepared from parts 0. The reactor was cooled, parts 3. The product was precipitated at pH 3, filtered, and washed with aqueous acetone to remove by-product salts. A slurry of the purified ether was neutralized with caustic to an aqueous solution pH of 7. By analysis this water-soluble ether had a hydroxypropyl MS of 1. In another run pts 1. It had a hydroxypropyl MS OF 1.
In the present work, yields and concentrations of 1,3-propanediol and citric acid registered for different isolated strains are also described. Microbial bioconversion of glycerol represents a remarkable choice to add value to the biofuel production chain, allowing the biofuel industry to be more competitive. The current review presents certain ways for the bioconversion of crude glycerol into citric acid and 1,3-propanediol with high yields and concentrations achieved by using isolated microorganisms.
Keywords: Biodiesel, Crude glycerol, 1, 3-PD, Citric acid, Strains, Fermentation Introduction and background Biodiesel Due to the continuously growing of world industrial output, every quantity of energy is needed. This energy is provided through biological, chemical, electrochemical or physical ways and mechanisms, starting from natural resources. One of these natural resources is well-known as petroleum and its byproducts, like petrol, diesel, gasoline, etc.
Due to the increased fuels demands on the market, these natural resources present some negative aspects because of the global ecological imbalance they have created. In this respect, an alternative fuel source is strongly necessary [ 1 ]. There are some researches which underline that petroleum production will decrease gradually until , and the reserves are thought to become completely exhausted by then.
Taking these into account, the demand for alternative fuels is growing worldwide and the use of biomass for producing biofuels is one of the most promising choices so far [ 2 , 3 ]. Biofuels represent a variety of combustibles which derive from biomass. In Europe, the best known biofuel is biodiesel.
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