The invention relates to spent yeast, and particularly to a method for producing or recovering food grade products from beverage production fermentation processes, such as breweries (spent brewer’s yeast), alcoholic beverage distilleries and others. BACKGROUND OF THE INVENTION

In the fermented beverage industries, such as breweries, distilleries, wine making and others, yeasts, such as brewer’s yeast, are used to ferment sugars from various sources.

After the main fermentation process is completed, some of the yeast may be reused for further fermentations. However, a large amount of yeast in liquid solution is surplus yeast and needs to be discarded, this being generally called spent yeast (a term that may include other terms such as the terms ‘lees’ in wine making and the like).

The spent yeast is a production residual consisting of a mix of materials containing substantially all of the original constituents of fresh yeast, significant amount of additional yeast that was created through the fermentation process and, among others, about 35% to 60% protein on a dry basis. With about 15% of the total by-products generated during brewing, spent yeast is usually the second biggest by product of the brewing process and a significant by-product of fermentation processes in other industries such as the wine industry.

Technologies exist that can turn spent yeast into a valuable resource. However, to date its industrial utilization is very limited, mainly because of the fast contamination and spoilage of spent yeast as a result of the activity of microorganisms. This has hampered the large scale use of some technologies for using spent yeast. Hence, spent yeast is mainly an organic waste that imposes heavy expenses on the producer due to its large volume and strict regulation regarding its disposal.

Known solutions for this waste are its disposal or transportation in its wet form as animal feed to farmers or to other secondary material processing producers.

Constituents of spent yeast include, without limitation, customized yeast extract (CYE), yeast cell wall (YCW), partially autolysed yeast (PAY) and bioactive peptides. SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for producing or recovering a food grade products from spent yeast discarded or otherwise obtained from a beverage fermentation process, as is described hereinbelow.

The method of the invention produces a stable and inexpensive source of quality proteins for the food industry, as well as an essential food nutrient which may be a substance which is not a genetically modified product or organism. The process gives off a much lower amount of carbon pollutants and other pollutants than prior art method for yeast production, and substantially reduces any environmental impact compared with prior art methods. The process also reduces transportation costs and volume because the product of the invention contains much less water and much less pollutants.

The process can be carried out using steam or other heat sources, such as heat generated during manufacturing operations, e.g., during beer brewing.

The process can include a clean-in-place (CIP) apparatus for producing and maintaining a food-grade yeast product.

The process can make use of clean or heated air that has been generated in drying processes (e.g., for drying bottles) for drying the yeast product or for packaging purposes.

The process of making the yeast product contains very little by-products and therefore significantly reduces the waste handling requirements of the manufacturer. In addition it provides several advantages: a) the process can produce yeasts with a unique and steady taste, flavor or odor; b) since in many cases there are several kinds of sources (such as kinds of beers), there are therefore several kinds of yeasts which can be produced with different and steady tastes, flavors or odors; c) different kinds of yeasts that come from different kinds of sources (such as different kinds of beers) can be collected in a balance tank and blended to produce many kinds of yeast mixtures with different and steady tastes, flavors or odors according to manufacturer requirements; d) the yeast products have improved, steady shelf-life; e) improved reduction of sugar and or salt content in food products.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawing in which: Fig. 1 is a simplified flow chart of a method for producing or recovering a food grade product from a beverage fermentation process, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Reference is now made to Fig. 1, which illustrates a method for producing or recovering a food grade product from a fermentation process, in accordance with an embodiment of the present invention.

The excess yeast that comes off the fermentation production line (i.e., production of a fermented product such as beer or wash for distillation) is transferred to and/or collected in an intermediate and/or a buffer and/or treatment vessel during the on-line process. The intermediate, buffer or treatment vessel can be part of the existing on-line process or an addition thereto.

The yeast may be separated from all or part of the hops or other substances or manufacturing ingredients before or after it is collected in the intermediate, buffer and/or treatment vessel.

The yeast may go through a process that lowers its liquid content, such as but not limited to, a drying, vacuum or centrifuge process, before or after it is collected in the intermediate, buffer and/or treatment vessel.

The yeast undergoes a deactivation process which can be done in the treatment vessel or in another part of the process, either by heating, drying or both heating and drying. The constituents of the beverage fermentation process are all considered food grade constituents, and in accordance with an embodiment of the invention, the yeast that undergoes deactivation is maintained at a food grade level and hence remains a food grade product. In another embodiment of the present invention the yeast may be downgraded to a feed grade product. “Deactivation” refers to reducing or eliminating the ability of the yeast to act as a leavening agent.

The deactivated yeast may be in the form of flakes, powder, bulk or paste, and the particular form may be chosen by the manufacturer. The deactivated spent yeast may or may not be ground, chopped, etc., before or after the deactivation and may be packaged as a food grade product. As mentioned before, the deactivated spent yeast may be dry, but alternatively, may be moist, again still food grade.

The process may include one or more intermediate tanks or intermediate collection vessels. The intermediate (or buffer) vessel receives the yeast flow from the production line; in one embodiment of the present invention, this enables handling and processing unequal flow rates from the production line and thus ensures a steady flow rate to the treatment vessel. In another embodiment of the invention the intermediate vessels may be used to collect yeast with a certain flavor or other characters and in another embodiment of the invention the intermediate vessels may be used to sort different yeasts from different vessels and create a yeast product with different qualities from blends of different yeasts. The intermediate vessel may be temperature controlled (heated or cooled) to maintain the food-grade status of the spent yeast product and/or to render the yeast additional qualities. The intermediate vessel is not for pasteurization; rather it assists in the control of the deactivation and preservation of the spent yeast (in most cases heating accelerates deactivation; cooling slows it). Pasteurization may be done in a separate dedicated intermediate vessel.

The intermediate vessel (or another dedicated vessel) may include additional components, such as sugars or other yeasts, so as to increase the amount of yeast which enters the deactivation treatment vessel. The intermediate vessels (or another dedicated vessel) may also include taste or flavor additives (including taste or flavor neutralizers), colors, odors, preservation additives and/or other additives which are beneficial to the end product. The process according to this invention may also include the addition of small quantities of the pre-fermentation ingredients, taken from any part of the production process. Such an intermediate vessel with additional components is applicable for the spent yeast of the beverage fermentation process of many industries, such as but not limited to, beer production, wine production, alcoholic beverage production or biofuel production and others, and thus can be advantageously used to increase the production of spent yeast products and modify the types of spent yeast products being produced. The components added in this vessel can be used to modify properties of the spent yeast product, such as but not limited to, the color or hue, odor, preservation properties, energy (calorie content) and many others.

The intermediate vessels may include one or more sensors that can detect many different kinds of properties in a closed control loop process, such as but not limited to, temperature sensors, pH sensors, moisture sensors, and many more. The closed control loop process is controlled by a controller in feedback communication with the sensors and which may incorporate artificial intelligence or machine learning techniques, such as but not limited to, reinforcement learning (RL) which may include the use of a Neural Network or deep reinforcement learning (DRL). Heating and drying can be carried out in any known method, such as but not limited to, mechanical, electrical, spray drying, centrifuge, and many others.

The excess humidity of the drying process can be used either by returning it to the main product stream (for example, the beer stream) or it may be used in a variety of other uses. The excess humidity may be discarded to regular sewage systems and may also be monitored for its qualities prior or during the discarding process.

Deactivation can be carried out in any known method, such as but not limited to, one or more of heating, drying, UV, high voltage, microwave, cavitation and others. The deactivated spent yeast may be coated afterwards, such as with food grade oil or wax.

The invention has many applications, such as but not limited to, beer brewing, alcoholic beverage production, such as wine or whiskey, biofuel and others.