PROCESS FOR PRODUCING A SEASONING AGENT, AND FOODS CONTAINING THE SAME

Abstract: A component for a taste-enriching seasoning is produced by a process, comprising 1) a first step in which a suspension of beer yeast is extracted with water under conditions where no sub­ stantial decomposition of cells of the beer yeast takes place, 2) a second step in which the extract is subjected to solid-­ liquid separation and then to sterilization or in which the extract is first subjected to sterilization and there­ after to solid-liquid separation, 3) a third step in which the pH of the extract is lowered to 2 to 4 at the latest before the sterili­ zation in the second step; and 4) a fourth step in which the extract obtained in the second step is concentrated and neutralized to a pH of 4.5 to 7.0, before or after the con­ centration. The product obtained by the described process may be combined with glutamic acid or with nucleic acid flavoring agent to obtain a taste-enrichting seasoning agent which is useful for improving the taste of foods.

Description: 1. Field of the Invention The present invention relates to a process for producing a seasoning component and to improved seasoning and food which possesses augmented richness in taste due to the addition of a water-extract of beer yeast and is free from bitterness and odour characteristic of beer yeast. 2. Description of the Prior Art The flavor-imparting function of monosodium L-glutamic acid (MSG), sodium inosine-5'-monophosphate (IMP) and sodium guanosine-5'-monophosphate (GMP), which are typical flavoring agents, is well known. They have been widely used for the purpose of enhancing such organoleptic properties as flavor and richness in taste, in combination with hydrolysates of vegetable proteins (HVP) or animal proteins (HAP), yeast extracts (YE), amino acids, etc., depending on their uses. With the widespread use of such flavoring agents, it has been desired to further enhance or augment their taste-enriching functions, including the function to enhance thickness, richness and persistence of taste, apart from the enhancement of taste based on the combined use with other flavoring agents capable of imparting saltyness, sweetness, sourness, etc. On the other hand, yeast extracts, i.e., autolysates and hydrolysates of yeast containing various amino acids and minerals, have been applied to various foods and seasonings. Yeast extracts have hitherto been produced by autolysis involving the decomposition of cells of yeast or by hydrolysis conducted under severe conditions involving treatments at elevated temperatures with the addition of chemicals for hydrolysing the cells of yeast. The inventors have previously found that water-extracts of yeast, namely extracts from yeast obtained by extraction with hot water under mild conditions where no substantial decomposition of cells of yeast takes place, have unique taste-enriching effects different from those of any known combinations of flavoring agents (see Japanese Patent Application Nos. 280,981/84 and 280,982/84) and continued investigations on optimum extraction conditions, storage stability of extracts, etc. As a consequence, it has been found that extracts obtained from beer yeast by means of hot water extraction involving no substantial decomposition of cells of yeast tend to assume odour and bitterness characteristic of beer yeast and that their taste-enriching function tends to be impaired during the course of sterilization after extraction. A process for producing yeast extract almost free from bitter taste is described in AU-B-33 535/78, where the extraction is performed at a pH of 7 to 10.5 or at a pH of 10.5 to 12.9. As far as hydrolysates and autolysates of yeast are concerned, it has been known that washing with water and super critical gas extraction can be effective for the removal of the bitterness. It has also been proposed to subject hydrolysates and autolysates of yeast to various deodorization treatments, such as washing with organic solvents, or to mask their odour by various means. The addition of methionine to a yeast extract in order to mask the bitterness and yeast odour of the obtained extract is described in GB-A-1 208 818. However, nothing has been known on the bitterness and odour of the hot water extracts from yeast, as well as on the protection, during thermal sterilization, of the taste-enriching function of hot water extracts from yeast. It is therefore desired to develop a process for commercially producing extracts having the desired taste-enriching function and free from the bitterness and odour characteristic of beer yeast. DESCRIPTION OF THE INVENTION In view of the above, the inventors have conducted intensive investigations and found that the impairment of the taste-enriching function of the yeast extract caused by thermal sterilization can be inhibited and the bitterness and the yeast odour can be suppressed by lowering the pH of the extracts. The present invention has been accomplished based on this finding. There is provided by the present invention a process for producing a taste-enriching seasoning component, which comprises preparing an extract from beer yeast, the pH of said extract being lowered to 2 to 4 before being sterilized at a temperature of 60 °C to 90 °C for a period of 1 to 30 minutes. This invention further provides a taste-enriching seasoning, containing the said component together with at least one flavoring agent selected from the group consisting of glutamic acid or salts thereof and nucleic acid flavoring agents. The invention makes it possible to attain a taste-enriching function to augment thickness, richness, persistence, etc., which could hardly be attained by combinations of such flavoring agents as MSG, IMP, GMP, HAP, HVP, other YEs, etc., or by combinations of these flavoring agents with other saltyness-, sweetness- or sourness-imparting flavoring agents. The invention relates to a food provided with augmented richness in taste which contains the said seasoning component or taste-enriching seasoning. In the first step of the present process, a suspension of beer yeast is extracted with water under conditions where no substantial decomposition of cells of yeast takes place. More specifically, a water suspension containing cells of yeast is treated, at a temperature of 40 to 55 °C for a period of 5 to 120 minutes, or at a temperature of 55 to 100 °C for a period of 1 to 60 minutes. Desired water-extracts of beer yeast can be effectively obtained under mild conditions described above. In contrast with the prior yeast extracts, the water-extracts prepared in accordance with the process of the invention are substantially free from hydrolysis. In the second step, the extract from the first step is subjected to solid-liquid separation by means of, e.g., centrifugation and then to thermal sterilization. The sterilization may be carried out after the separation of solids. When the sterilization is carried out after the solid-liquid separation and a pH-lowering treatment described hereinbelow, it is often required to again remove precipitates formed after the solid-liquid separation. In such a case, it may be preferred to subject the extract to a pH-lowering treatment immediately after extraction and then to a solid-liquid separation treatment to remove the precipitates formed, so as to perform the separation of solids from liquid by one single step. The sterilization is carried out at a temperature of 60 to 90 °C for a period of 1 to 30 minutes. The third step is a pH-lowering treatment. The pH-lowering treatment can be effected in either the first or second step described above. In either case, the pH of the extract must be lowered before the sterilization treatment. To be more specific, the pH of the extract can be lowered to 2 to 4 before the extraction in the first step, before the solid-liquid separation in the second step, or before the sterilization in the second step. As an agent for lowering the pH, there can be used various organic and inorganic acids, including hydrochloric acid. When the pH of the extract is higher than 4, the taste-enriching function of the extract may be deteriorated by various germs and the bitterness anti the yeast odor could not be suppressed. On the other hand, when its pH is lower than 2, an undesirably large amount of neutralizer will be required. In the third step, the extract obtained in the second step is concentrated and neutralized. The concentration is preferably carried out at a low temperature (40 to 60 °C) for a short period of time. The temperature and the duration of the concentration may be varied depending on the degree of concentration (or the density of solids). A neutralizer, such as sodium hydroxide, can be added to the extract to raise its pH to 4.5 to 7.0, preferably 5.5 to 6.0, to obtain desired beer yeast extract. If desired, the water-insoluble residues removed in the second step can be subjected to autolysis or hydrolysis by use of acids, alkalis or enzymes, so as to utilize them as ordinary yeast extracts. There are no particular limitations on the ratio of the thus obtained water extract of yeast to the flavoring agents. It can, however, be preferable to use the extract in an amount, in terms of the dried mass (hereinafter referred to as "DM"), of 0.001 to 100 times that of the flavoring agents, in terms of the weight of MSG that gives the same taste level. In the case of a food, the extract is added thereto in an amount, in terms of DM, of 0.1 to 30% by weight. When the amount of the yeast extract is used in an amount exceeding the upper limit described above, an excessively thick taste may result, and the total balance of taste tends to be deteriorated, although the taste can be distinctly enriched. On the other hand, when it is less than the above lower limit (less than 0.001 times that of MSG in the case of a seasoning and less than 0.1% in the case of a food), substantial taste-enriching effects may not be attained. Flavor-imparting ingredients to be used in combination with the water-extract of the invention include MSG, IMP, GMP, potassium glutamate, calcium glutamate, potassium inosine-5'-monophosphate, calcium inosine-5'-monophosphate, potassium guanosine-5'-phosphate and calcium guanosine-5'-phosphate. It is also possible to use foods or other seasonings that contain any of the above ingredients, for example, HAV, HVP, YE, meat extracts, fish extracts, and vegetable extracts. The taste-enriching seasoning of the present invention can be prepared by any method. For example, it can be prepared by admixing a water-extract of yeast with a solution of MSG, IMP, GMP, etc., or by admixing a dried product of the yeast extract with powders of MSG, IMP, GMP, etc. It is also possible to shape it into granules, together with an appropriate excipient. The food possessing enriched taste according to the invention can be prepared by any method, provided that the water extract of yeast and the flavor-imparting ingredients come to be present therein. It is a matter of course that other conventional ingredients can be additionally used in the seasoning or food of the invention, without departing from the objectives of the present invention. Examples of other ingredients usable in the invention include saltyness-imparting substances, such as sodium chloride and potassium chloride; sweeteners, such as sugar; sourness-imparting substances, such as organic acids, etc.; aromatics; spices; quality-improving agents. According to the present invention, taste-enriching substances which are free from bitterness and yeast odour can be readily extracted from beer yeast, and the combination of the extract and flavor-imparting ingredients is not only capable of augmenting the impression of taste without altering such original tastes as savoriness, bitterness, sweetness, sourness, saltness, etc., but also capable of enhancing the richness in taste, such as persistence, richness, thickness, etc. EXAMPLE 1 Water was added to a slurry of beer yeast obtained as a by-product in the production of beer, and the mixture, after being well stirred, was subjected to centrifugation to give a slurry of washed beer yeast (D.M., 23%; pH, 6.0). To this slurry (430 kg) was added the equal amount of water, and the resulting mixture was heated at 60 °C for 10 minutes. Thereafter, it was rapidly cooled and added with 2.9 kg of hydrochloric acid to adjust its pH to 3. The resulting mixture was subjected twice to centrifugation (in the second centrifugation, 400 kg of water was added to the residue of the first centrifugation). The thus separated liquid portions were combined, and the combined liquid was sterilized at 80 °C for 5 minutes. After the completion of the sterilization, the resulting solution was vacuum concentrated at 50°C for 3 hours, and then 1.1 kg of sodium hydroxide was added thereto to raise its pH to 6.0. To this was added 5 kg of sodium chloride to give 63 kg of beer yeast extract (D.M., 25.3 kg; water content, 60%; NaCl, 6.6 kg). As a control, an extract of beer yeast was prepared in the same manner as above, except that its pH was not adjusted, that is to say, sodium hydroxide was not added thereto. The thus obtained two kinds of beer yeast extracts were applied to two evaluation systems set forth below, and their odour, bitterness, flavor, and richness in taste were rated. Results obtained are shown in Table 1. Evaluation System A : MSG, 0.05%; IMP, 0.05%; NaCl, 0.7%; and beer yeast extract, 0.5% (reduced to pure extract ) Evaluation System B : Consomme , 1.5%; NaCl, 0.3%; and beer yeast extract, 0.2% (reduced to pure extract ). EXAMPLE 2 Water was added to a slurry of beer yeast obtained as a by-product in the production of beer, and the mixture after being well stirred, was subjected to centrifugation to give a slurry of washed beer yeast (D.M., 23%; pH, 6.0). To this slurry (430 kg) was added equal amount of water, and the mixture was heated at 60 °C for 10 minutes. The resulting mixture was subjected twice to centrifugation in the same manner as in Example 1. The thus separated liquid portions were combined, and the pH or the combined liquid was adjusted to 3 by the addition of hydrochloric acid. Precipitates formed were filtered off (DM of the precipitates, 6.0 kg). The filtrate was sterilized at 80 °C for 5 minutes and then subjected to a condensation treatment for a short period of time by use of a thin film continuous condenser (temperature of filtrate, 55 °C; residence time, ca. 1 min.). Thereafter, 1.0 kg of sodium hydroxide was added to the condensate to raise its pH to 5.8. To this was added 5.1 kg of sodium chloride to obtain beer yeast extract according to the invention (water content, 60%; DM, 25.1 kg; NaCl, 6.6 kg). An aqueous solution containing 0.5% (reduced to pure extract) of the thus obtained beer yeast extract, 0.05% of MSG, 0.05% of IMP and 0.7% of NaCl was prepared and subjected to an organoleptic test. It was evaluated as follows: It possesses distinct richness in taste and strong flavor, and neither bitterness not beer odour is observed. EXAMPLE 3 Water was added to a slurry of beer yeast obtained as a by-product in the production of beer, and the mixture, after being well stirred, was subjected to centrifugation to give a washed beer yeast slurry (DM, 23%; pH, 6.0). To this slurry (430 kg) was added equal amount of water, and its pH was adjusted to 3.0. The resulting mixture was heated at 60 °C for 10 minutes, during which hydrochloric acid was added to the mixture to maintain its pH at 3.0 (if it is not added, the pH of the mixture rises due to extracts from the yeast). Thereafter, the mixture was subjected twice to centrifugation in the same manner as in Example 1, and the separated liquid portions were combined and sterilized at 80 °C for 5 minutes. After the sterilization, the combined liquid was vacuum concentrated at 55 °C for 2 hours and added with 0.9 kg of sodium hydroxide to raise its pH to 6.0. To this was added 5 kg of sodium chloride to obtain beer yeast extract (DM, 21.5 kg; water content, 60%; NaCl, 6.2 kg). An aqueous solution containing 0.5% (reduced to pure extract) of the thus obtained beer yeast extract, 0.05% of MSG, 0.05% of IMP and 0.7% of NaCl was prepared and subjected to an organoleptic test. It was evaluated as follows: It possesses distinct richness in taste and strong flavor, and neither bitterness nor beer odour is recognized. EXAMPLE 4 Taste-enriching seasonings were prepared by employing MSG, IMP, GMP and beer yeast extracts according to the present invention, in accordance with the recipes shown in Table 2. As a control, there was prepared a seasoning not containing beer yeast extract. The samples were organoleptically evaluated by two point comparison method. Results obtained are shown in Table 3.

Claims: A process for producing a taste enriching seasoning component, comprising the following steps : 1) a first step in which a suspension of beer yeast is extracted with water at a temperature of 40 to 55°C for a period of 5 to 120 minutes, or at a temperature of 55 to 100°C for a period of 1 to 60 minutes where no substantial decomposition of cells of the beer yeast takes place; 2) a second step in which the extract is subjected to solid-liquid separation and then to sterilization at a temperature of 60 to 90°C for a period of 1 to 30 minutes; 3) a third step in which the pH of the extract is lowered to 2 to 4 at the latest before the sterilization at a temperature of 60 to 90°C for a period of 1 to 30 minutes in the second step; and 4) a fourth step in which the extract obtained in the second step is concentrated and neutralized to a pH of 4.5 to 7.0, before or after the concentration. A process for producing a taste enriching seasoning component, comprising the following steps : 1) a first step in which a suspension of beer yeast is extracted with water at a temperature of 40 to 55°C for a period of 5 to 120 minutes, or at a temperature of 55 to 100°C for a period of 1 to 60 minutes where no substantial decomposition of cells of the beer yeast takes place; 2) a second step in which the extract is subjected to sterilization at a temperature of 60 to 90°C for a period of 1 to 30 minutes and then to solid-liquid separation; 3) a third step in which the pH of the extract is lowered to 2 to 4 at the latest before the sterilization in the second step; and 4) a fourth step in which the extract obtained in the second step is concentrated and neutralized to a pH of 4.5 to 7.0, before or after the concentration. A process according to claim 1, wherein the pH-lowering treatment is carried out immediately after the extraction step and before the solid-liquid separation. A taste-enriching seasoning agent, containing a seasoning component obtained by the process of any of the claims 1 to 3 and at least one flavouring agent selected from the group consisting of glutamic acid or salts thereof and nucleic acid flavouring agents. A seasoning agent according to claim 4, which contains the seasoning component obtained by the process of any of the claims 1 to 3 in an amount, in terms of the dried mass, of 0.001 to 100 times that of the flavouring agent, in terms of the weight of MSG that gives the same taste level. A seasoning agent according to claim 4 or 5, which additionally contains conventional seasoning ingredients. A seasoning agent according to any of the claims 4 to 6, which is in the form of a dry powder or in granular form. A food possessing augmented richness in taste, containing at least one flavouring agent selected from the group of glutamic acid or salts thereof and nucleic acid flavouring agents, characterized by further containing a seasoning component obtained by the process of any of the claims 1 to 3. A food having augmented richness in taste, comprising a seasoning agent according to any of the claims 4 to 7.

Inventors: SUSUMU, TSUJIMOTO C/O CENTRAL RESEARCH LAB., TADASHI, MIZUTANI C/O CENTRAL RESEARCH LAB., TOSHINORI, SAEKI C/O CENTRAL RESEARCH LAB.
Applicants: AJINOMOTO CO., INC.
Application year: 1987
Main classification: A23L1
IPC codes: A23L1