Method for Processing Oil Crops with Rhodotorula

Abstract

The disclosure discloses a method for processing oil crops with Rhodotorula, and belongs to the technical field of fermentation. The method includes the step of inoculating the Rhodotorula (such as Rhodotorula mucilaginosa, Sporidiobolus salmonicolor and Rhodotorula glutinis) that can produce carotenoid into a fermentation medium that contains oil-rich oil crops for solid state fermentation to obtain oil and oil crop meal rich in carotenoid. The carotenoid as a fermentative metabolite of the Rhodotorula has bioactivities of resisting oxidation, preventing vascular sclerosis, enhancing immunity and preventing cancers. Contents of carotenoid in the oil and oil crop meal acquired by the method can be up to 9.071 μg/g and 8.062 μg/g correspondingly. By the method, the oil and oil crop meal rich in carotenoid can be acquired at the same time by just once fermentation and once oil pressing without additional functional substances, and thus the production cost of the functional oil and the fermentation oil crop meal is greatly reduced.

Claims

1. A method for processing oil crops, comprising the steps of performing solid state fermentation on Rhodotorula that produces carotenoid in a fermentation medium and obtaining a fermented product in solid state; and pressing oil from the fermented product to obtain oil and oil crop meal; wherein the fermentation medium comprises oil crop powder; wherein the oil crop powder comprises one or more of soybean extruded powder, soybean powder, peanut powder, rapeseed powder, castor powder and sesame powder.

2. The method of claim 1, wherein performing solid state fermentation comprises inoculating the Rhodotorula into the fermentation medium; wherein the fermentation medium is a mixture of oil crop powder and water.

3. The method of claim 2, wherein the fermentation medium comprises, by mass, the oil crop powder which is 35-45% of a total mass of the fermentation medium and the water which is 55-65% of the total mass of the fermentation medium.

4. The method of claim 3, wherein the fermentation medium consists of the oil crop powder which is 40% the total mass of the fermentation medium and the water which is 60% the total mass of the fermentation medium.

5. The method of claim 3, wherein conditions for the solid state fermentation are at a temperature of 25-30° C. and a time of 3-6 d.

6. The method of claim 5, wherein conditions for the solid state fermentation are at a temperature of 30° C. and a time of 4 d.

7. The method of claim 5, comprising inoculating a bacteria solution of Rhodotorula for fermentation.

8. The method of claim 7, wherein a volume of inoculated bacteria solution of Rhodotorula is 10-15% of a mass of the oil crop powder; and a cell concentration of the inoculated bacteria solution of Rhodotorula is 1×10.sup.8-1×10.sup.10 CFU/mL.

9. The method of claim 8, wherein the Rhodotorula comprises one or more of Rhodotorula mucilaginosa, Sporidiobolus salmonicolor and Rhodotorula glutinis.

10. The method of claim 9, wherein the Rhodotorula is Rhodotorula glutinis.

11. The method of claim 10, wherein the fermentation medium comprises the soybean extruded powder and the water.

12. Oil and/or oil crop meal, prepared by the method of claim 11, wherein the oil and oil crop meal are rich in carotenoid.

13. A product that comprises the oil and/or oil crop meal of claim 12.

14. The product of claim 13, wherein the product is a feed, a food, a drug or a healthcare product.

Description

BRIEF DESCRIPTION OF FIGURES

[0026] FIG. 1 shows functional oil acquired by extraction after solid state fermentation of extruded soybeans with different kinds of Rhodotorula.

DETAILED DESCRIPTION

[0027] The disclosure is further described in conjunction with Examples as follows.

[0028] Rhodotorula mucilaginosa, Sporidiobolus salmonicolor and Rhodotorula glutinis involved in following Examples are all purchased from the China General Microbiological Culture Collection Center and have serial numbers: CGMCC No. 2.5511, CGMCC No. 2.4290 and CGMCC No. 2.5570 correspondingly; and soybean extruded powder involved in following Examples comes from Shandong Bohai Oil Industry Co., Ltd., and peanut powder and rapeseed powder are both purchased from farmer's markets in Wuxi (Rhodotorula mucilaginosa CGMCC No. 2.5511, Sporidiobolus salmonicolor CGMCC No. 2.4290 and Rhodotorula glutinis CGMCC No. 2.5570 can all be purchased and do not need deposit for patent procedure).

[0029] A medium involved in following Examples is as follows:

[0030] A YPD seed medium (m/v): peptone 2%, yeast 1% and glucose 2%.

[0031] Detection methods involved in following Examples are as follows:

[0032] Analysis of functional oil and oil crop meal:

[0033] 1. Extraction

[0034] A solid state fermented product is dried at 50° C. until a water content reaches 5-10%; the dried fermented product and n-hexane are mixed at a mass ratio of 1:30, soaked and stirred for 24 h; suction filtration is performed and a filtrate is taken; and the filtrate is rotary evaporated at 50° C. by a rotary evaporator to obtain the functional oil and oil crop meal.

[0035] 2. Measurement of type and content of fatty acid in functional oil

[0036] 50 mg of the acquired functional oil is taken and added to 2 mL of a 0.5 mol/L NaOH—CH.sub.3OH solution; the mixture is saponified in a water bath for 30 min at 65° C., cooled to room temperature, and 2 mL of a 14% BF.sub.3—CH.sub.3OH solution is added; the mixture is saponified in a water bath for 30 min at 65° C., cooled to room temperature, and 5 mL of n-hexane is added to oscillate for 3-4 min to extract fatty acid methyl ester; a little of anhydrous Na.sub.2SO.sub.4 is added for dewatering treatment; centrifuging is performed for 5 min at 10,000 r/min; an upper layer organic phase is taken to pass through a 0.22 μm organic film for use; a 0.2 mg/mL nonadecanoic acid methylester solution (with n-hexane as a solvent) is added to a solution subjected to methyl esterification and film passing at a volume ratio of 1:1 to serve as an internal standard; and the content of the fatty acid in the extract is measured by a GC-MS.

[0037] 3. Extraction and content measurement of carotenoid in functional oil

[0038] (1) 0.5 g of functional oil is accurately weighed and added into a 10 mL brown glass volumetric flask, reaches a constant volume with dichloromethane and is shaken up, and its OD value is measured at a light absorption wavelength of 450 nm and is substituted into a standard curve to calculate the content of the carotenoid.

[0039] (2) the standard curve of the content of the carotenoid is formulated: a 0.2 mg/mL β-carotene standard solution is prepared, 0, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2 and 6.4 mL of β-carotene standard solutions are sucked correspondingly to reach a constant volume 10 mL with dichloromethane, their OD values are measured at a light absorption wavelength of 450 nm, and a standard product curve is drawn.

[0040] 4. Extraction and content measurement of carotenoid in oil crop meal

[0041] 500 mg of oil crop meal is accurately weighed and put into a brown flask, 5 mL of acetone is added for ultrasonic treatment for 2 h, and the flask is taken out and shaken up every 20 min; the solution is centrifuged for 10 min at 10,000 rpm after ultrasonic treatment, and a supernate is taken; and the content of the carotenoid in the oil crop meal is measured by the measurement method for the content of the carotenoid in the functional oil.

[0042] Detection method of cell concentration:

[0043] 1 mL of a seed solution of Rhodotorula is taken to a cuvette, OD.sub.600 is measured, then the seed solution is diluted with normal saline, the number of cells of the Rhodotorula is counted by a 25×16 blood counting chamber, and the cell concentration is calculated.

[0044] The cell number in each mL=(cell number counted by blood counting chamber/80)×400×10000×dilution ratio.

EXAMPLE 1

Using Soybean Extruded Powder as Raw Material

[0045] Specific steps are as follows:

[0046] (1) a strain of Rhodotorula preserved at 4° C. is inoculated into a YPD seed medium (sterilized for 20 min at 115° C.) for culturing for 2 d at 30° C. and a rotating speed of 200 r.Math.min.sup.−1 to obtain activated fluid.

[0047] (2) 80 mL of the YPD seed medium is taken and put into a 250 mL conical flask (sterilized for 20 min at 115° C.) and 200 pi of the activated fluid obtained in step (1) is inoculated into the YPD seed medium for culturing for 2 d at a temperature of 30° C. and a rotating speed of 200 r.Math.min.sup.−1 to obtain a seed solution, where a cell concentration in the seed solution is about 9×10.sup.9 CFU/mL at the moment.

[0048] (3) 300 g of a fermentation medium is taken and put into a 2500 mL conical flask (sterilized for 30 min at 121° C.), and the seed solution is inoculated into the fermentation medium in accordance with fermentation parameters in Table 1 for solid state fermentation to obtain a fermented product.

[0049] Oil extraction is performed on the obtained fermented product by the analysis method of the functional oil and oil crop meal to obtain the functional oil and fermented bean meal; and the obtained functional oil and fermented bean meal are analyzed by the analysis method of the functional oil and oil crop meal, and analysis results are shown in Tables 2-4. The blank group is original soybean extruded powder without microbial fermentation.

[0050] The functional oil obtained by the original soybean extruded powder, group A, group B and group C is shown in FIG. 1, and the functional oil extracted from original extruded soybeans is golden yellow, the functional oil obtained by group A is light orange, the functional oil obtained by group B has a darker color than group A and is reddish orange, and the functional oil obtained by group C has the darkest color and is almost red.

TABLE-US-00001 TABLE 1 Fermentation parameters Inoculum Fermentation Group Strain Size Medium conditions Group A Group Rhodotorula 12 mL Soybean extruded powder 120 30° C., 4 d A1 mucilaginosa g, water 180 g Group Rhodotorula 21 mL Soybean extruded powder 140 25° C., 4 d A2 mucilaginosa g, water 160 g Group Rhodotorula 13 mL Soybean extruded powder 110 28° C., 6 d A3 mucilaginosa g, water 190 g Group B Group Sporidiobolus 18 mL Soybean extruded powder 120 30° C., 4 d B1 salmonicolor g, water 180 g Group Sporidiobolus 18 mL Soybean extruded powder 140 25° C., 4 d B2 salmonicolor g, water 160 g Group Sporidiobolus 16.5 mL   Soybean extruded powder 110 28° C., 6 d B3 salmonicolor g, water 190 g Group C Group Rhodotorula 18 mL Soybean extruded powder 120 30° C., 4 d C1 glutinis g, water 180 g Group Rhodotorula 14 mL Soybean extruded powder 140 25° C., 4 d C2 glutinis g, water 160 g Group Rhodotorula 14 mL Soybean extruded powder 110 28° C., 6 d C3 glutinis g, water 190 g

TABLE-US-00002 TABLE 2 Content of carotenoid in functional oil and fermented bean meal Carotenoid Oil (μg/g Bean meal (μg/g Group functional oil) fermented bean meal) Blank Group 7.286 0.623 Group A Group A1 7.513 8.062 Group A2 7.652 7.975 Group A3 7.751 8.059 Group B Group B1 8.462 2.161 Group B2 8.367 2.059 Group B3 8.453 2.112 Group C Group C1 9.071 7.627 Group C2 8.976 7.484 Group C3 9.031 7.575

TABLE-US-00003 TABLE 3 Type and content of fatty acid in functional oil (mg/g functional oil) Group A Blank Group Group A1 Group A2 Group A3 C14:0 0.305 0.268 0.254 0.276 C16:0 46.976 44.832 45.667 48.492 C16:1 0.406 0.387 0.362 0.435 C18:0 16.803 16.122 16.101 16.556 C18:1 108.598 108.652 107.576 109.112 C18:2 223.761 223.592 221.347 225.379 C18:3 25.015 24.394 23.560 23.673 C20:0 1.515 1.400 1.297 1.378 C20:1 1.0521 1.018 0.984 1.027 C22:0 1.713 1.604 1.542 1.669 SFA/UFA 0.186 0.179 0.183 0.190

TABLE-US-00004 TABLE 4 Type and content of fatty acid in functional oil (mg/g functional oil) Group B Group C Group Group Group Group Group Group B1 B2 B3 C1 C2 C3 C14:0 0.361 0.314 0.372 0.333 0.320 0.354 C16:0 54.176 52.880 56.076 45.284 44.187 46.583 C16:1 0.589 0.525 0.587 0.541 0.512 0.564 C18:0 19.640 18.352 19.896 16.494 16.087 16.809 C18:1 124.662 121.672 126.176 119.285 118.817 121.304 C18:2 253.395 250.768 254.098 236.165 234.734 236.189 C18:3 28.553 26.125 29.174 25.428 24.126 25.765 C20:0 1.748 1.720 1.759 1.457 1.217 1.468 C20:1 1.207 1.163 1.213 1.113 1.089 1.119 C22:0 2.019 1.986 1.987 1.729 1.703 1.790 SFA/UFA 0.191 0.188 0.195 0.171 0.167 0.174
Note: SFA refers to saturated fatty acid; MUFA refers to monounsaturated fatty acid; PUFA refers to polyunsaturated fatty acid; and UFA refers to unsaturated fatty acid.

[0051] It can be known from Table 2 that the functional ingredient carotenoid is added to both the functional oil and bean meal obtained by fermenting the extruded soybeans with the Rhodotorula and further processing, and the oil is endowed by the carotenoid with physiological functions of increasing immunity of a host, preventing vascular sclerosis, restraining tumors, resisting oxidation and retraining free radicals. It can be known from Tables 3-4 that the contents of different fatty acids in the functional oil do not obviously change, but there is rich unsaturated fatty acid; thus, the functional oil prepared in the disclosure has a better healthcare function.

EXAMPLE 2

Using Peanut Powder as Raw Material

[0052] Specific steps are as follows:

[0053] (1) The same as Example 1.

[0054] (2) The same as Example 1.

[0055] (3) Peanuts are put into a hot air circulating oven and dried at 50° C. until a water content reaches 5-10%, then the peanuts are husked, and the husked peanuts are ground into fine peanut powder.

[0056] (4) The peanut powder replaces soybean extruded powder, and 300 g of a fermentation medium is taken and put into a 2500 mL conical flask (sterilized for 30 min at 121° C.) and a seed solution is inoculated into the fermentation medium in accordance with the fermentation parameters in Table 1 for solid state fermentation to obtain a fermented product.

[0057] Oil extraction is performed on the obtained fermented product by the analysis method of the functional oil and oil crop meal to obtain the functional oil and fermented bean meal; after the obtained functional oil and fermented bean meal are analyzed by the analysis method of the functional oil and oil crop meal, it is found that the peanut oil and peanut meal both have rich carotenoid; and the presence of the carotenoid endow the oil certain physiological functions, improves the quality of the peanut meal, and comprehensively improves the nutritional values of the oil and peanut meal.

EXAMPLE 3

Using Rapeseed Powder as Raw Material

[0058] Specific steps are as follows:

[0059] (1) The same as Example 1.

[0060] (2) The same as Example 1.

[0061] (3) Rapeseeds are put into a hot air circulating oven and dried at 50° C. until a water content reaches 5-10%, then the rapeseeds are husked, and the husked rapeseeds are ground into fine rapeseed powder.

[0062] (4) The rapeseed powder replaces soybean extruded powder, and 300 g of a fermentation medium is taken and put into a 2500 mL conical flask (sterilized for 30 min at 121° C.) and a seed solution is inoculated into the fermentation medium in accordance with the fermentation parameters in Table 1 for solid state fermentation to obtain a fermented product. Oil extraction is performed on the obtained fermented product by the analysis method of the functional oil and oil crop meal to obtain the functional oil and fermented bean meal; after the obtained functional oil and fermented bean meal are analyzed by the analysis method of the functional oil and oil crop meal, it is found that the rapeseed oil and rapeseed meal both have rich carotenoid; and the presence of the carotenoid endows the oil certain physiological functions, improves the quality of the rapeseed meal, and comprehensively improves the nutritional values of the oil and rapeseed meal.