US1643047A

US1643047A - Method of drying yeast

Info

Publication number: US1643047A
Application number: US680528A
Authority: US
Inventors: Arnold K Balls
Original assignee: Individual
Current assignee: Individual
Priority date: 1923-12-13
Filing date: 1923-12-13
Publication date: 1927-09-20
Anticipated expiration: 1944-09-20

Description

Patented Sept. 20, 1927.

UNITED STATES.

PATENT OFFICE.

ARNOLD K. BALLS, OF PHILADELPHIA, PENNSYLVANIA;

mnrnon on name user.

No Drawing. Application filed'neoeniber 13, 1923, Serial No. 680,528. Renewed August 16, 1927.

This invention relates to methods of dryin yeast.

he development of methods for drying yeast without impairing the baking strength or the keeping qualities of the yeast has been a matter of much investigation, and various methods for drying yeast have been developed. As a general rule, the ordinary yeast races sold for baking in this country and submitting it to a rapid drying operation at a relatively high temperature.

This method differs from those heretofore proposed in that the conditions for the most rapid possible drying have been studied, and both by adding to the yeast an inert substance to increase its porosity and by work ing at greatly raised temperatures and with very dry air, the time of drying has been reduced to from one-third to one-sixth of that heretofore considered necessary. The advantage of sucha rapid process is obvious,

5 not only from the standpoint of increased technical production, but also by avoiding the necessity of keeping moist yeast for hours in the apparatus at temperatures favorable to autolysis, growth of infections,

and general weakening of the yeast.

The use of vacuum drying apparatus is unnecessary, and the inst-ant drying of the 'yeast by spray driers is harmful to the product.

The yeast is grown in the usual manner, separated and compressed, and about 10 per cent of its weight of substantially pure cellulose free from soluble impurities and white or light in color, is then added to the yeast.

The yeast is then finely divided and placed in layers of from one-fourth to three-fourths of an inch in thickness in a tray drier and submitted to the drying operation. In drying the yeast, a starting temperature of from 20 to 30 C. is employed and prefer- "fibre by digesting it with dilute acids if any .ably a temperature of 25 0., and a depresdepression are maintained throughout the process and suflicient volume of air may be employed to complete the drying in from 3 to 4 hours.

Either of the drying methods may be employed. The alternative process set forth requires considerable more equipment to produce the proper air conditions in the presence of moist yeast than the condition set forth in the preferred form of the process.

The maximum hygrometric depressions attained are those of practically dry air. There is an apparent advantage aside from the time saved, to be gained by employing the heavy currents of air necessary to produce these results.

The purified cellulose em loyed is repared from bran, rice polis ings or limt starch is present. I have found that a solution of 1 per cent hydrochloric acid may be employed for removing the starch. The cellulose is then mixed and stirred with a small amount of bleaching powder, sodium hypochlorite or chlorine, washed, and dried.

Yeast dried according to either of the methods set forth when previously mixed with cellulose as described, will keep its baking strength unimpaired for at least one month at ordinary room temperatures, as compared with the baking strength of an equivalent quantity of fresh yeast. By keeping the dried yeast at temperatures below 20 0., the original baking strength may be kept for many months. If the yeast is kept below 5 no deterioration occurs within a period of two years. By keeping the yeast at temperatures below 0 G., I have found that the baking qualities are even improved at the end of two or three months.

A suitable amount of calcium sulfate,

. from 2 per cent to 5 per cent by weight, may

be added to increase the baking strengh of the yeast.

The maximum temperature of 40 employed in the drying operation may be slightly varied and a temperature of about 43 C. may be employed. When nearly dry, the yeast can stand higher temperatures for fairly short periods and a temperature (4550) approaching the thermal death C point of wet yeast, has been employed without impairing the yeast.

The use of the cellulose filler greatly facilitates drying and apparently adds to the keeping quality of the dried yeast by adsorbing carbon dioxid, butyric acid, acetic acid, and the like, which are gradually liberated from dry yeast on storage.

The filler also presents an economic advantage in that the amount of time necessary to complete the drying operation is materially reduced. When the drying operation is performed according to the first method described, the apparatus is very simple and inexpensive. No vacuum unit is employed and no dehumidifying agent is necessary.

While I have described in detailthe preferred practice of my process, it is to be understood that the details of procedure may be widely varied, without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. The herein described product comprising a mixture of dried yeast and cellulose.

2. The hereindescribed product comprising a mixture of dried yeast and substantially 30cper cent by weight of cellulose.

3. he herein described process of drying yeast which comprises adding cellulose thereto and subjecting the mixture to a drying action.

4. The process of drying yeast which comprises adding cellulose to a yeast and dryin it at a temperature between 20 C. and 40 5. The process of drying yeast which comprises adding cellulose to a yeast and drying it at a temperature between 20 C. and 40 in an atmosphere having a depression between 10 and 18.

. 6. The process of drying yeast which comprises adding cellulose to a yeast and drying it with an initial temperature of from 20 C. to 30 C. in an atmosphere having a depression of substantially 10, increasing the temperature to substantially a0", and the depression to 15 to 18.

7. The process of drying yeast which comprises adding cellulose to a yeast and dry ing it for a period of 6 to 8 hours in an atmosphere having an initial temperature of substantially 25 C. and a depression of.

substantially 10, and increasing the temperature to substantially 40 C. and the depression to from 15 to 18.

8. The process of drying yeast which comprises adding cellulose and drying With practically dry air at a temperature of 35 to 40 C. and in sufiicient volume to reduce the moisture content to approximately 10 per cent in about three hours.

9. The'process of dryin yeast which com-' prises adding cellulose t iereto, submitting the mixture to treatment with heated air until dry. and controlling the temperature and l"