Pasteurisation of microbial biomass suitable for food applications

Abstract

The invention relates to a method for pasteurising a biomass, for example a fungal biomass, wherein the biomass is pasteurised using specific time and temperature parameters to obtain pasteurised biomass. The pasteurised biomass is suitable for use as a source of single-cell proteins in food products. The invention also relates to the pasteurised product, and to food products comprising it.

Claims

1. Method for pasteurising a biomass, comprising the steps of: i) providing a biomass; ii) pasteurising the biomass to obtain pasteurised biomass, wherein the biomass is pasteurised for at most 45 minutes at a temperature of at least 70° C., and iii) optionally recovering the pasteurised biomass.

2. The method according to claim 1, wherein the biomass is derived from a fermentation broth.

3. The method according to claim 2, wherein the fermentation broth comprises a biomass dry matter content of at most 6%, or wherein the fermentation broth is sieved to obtain the biomass.

4. The method according to claim 1, wherein the pH of the biomass in step ii) is at most 4.5.

5. The method according to claim 1, wherein the biomass comprises at least 7% dry matter.

6. The method according to claim 1, wherein the biomass is a biomass derived from a fungal strain.

7. The method according to claim 6, wherein the fungal strain is a strain of a fungal genus selected from the group consisting of Rasamsonia, Talaromyces, Penicillium, Acremonium, Humicola, Paecilomyces, Chaetomium, Rhizomucor, Rhizopus, Thermomyces, Mycehophthora, Thermoascus, Thielavia, Mucor, Stibella, Melanocarpus, Malbranchea, Dactylomyces, Canariomyces, Scytalidium, Myriococcum, Corynascus, and Coonemeria.

8. The method according to claim 1, wherein the pasteurisation is performed in an in-line heating unit that preferably comprises a pipe heater, a heating block, or a steam infusion element, more preferably a steam infusion element, and wherein the in-line heating unit optionally comprises a mixing element such as a static mixer.

9. The method according to claim 1, wherein the pasteurisation is performed for at most 5 minutes.

10. The method according to claim 1, wherein pasteurisation is performed at a temperature of at least 74° C.

11. The method according to claim 1, wherein the germ count of the pasteurised biomass has a log 10 reduction of at least 7.

12. The method according to claim 1, wherein in step i) a biomass derived from a submerged fermentation of the strain Rhizomucor pusillus is provided, and wherein in step ii) the biomass flows through an in-line heating unit where it has a residence time of about 1 to 2 minutes at a temperature of about 86° C.

13. Pasteurised biomass obtained by a method as described claim 1.

14. Food or feed product comprising the pasteurised biomass according to claim 13.

15. (canceled)

16. The pasteurised biomass according to claim 13, wherein the biomass comprises from about 6% to 12% lipids and from about 35% to 55% proteins, based on dry weight.

17. The method according to claim 7, wherein the fungal genus is Rhizomucor.

18. The method according to claim 7, wherein the fungal strain Rhizomucor pusillus.

19. The method according to claim 18, wherein the fungal strain is Rhizomucor pusillus strain CBS 143028, or a strain that is a single colony isolate or a derivative thereof.

Description

DESCRIPTION OF DRAWINGS

[0122] FIG. 1A-7D kill curve for pasteurisation of fungal biomass comprising 10% dry matter.

[0123] FIG. 1B-12D kill curve for pasteurisation of fungal biomass comprising 10% dry matter.

EXAMPLES

Example 1—Production of Pasteurised Single-Cell Protein

[0124] Rhizomucor pusillus strain CBS 143028 was fermented as described in WO2018/029353. Alternately, Rhizomucor pusillus strain CBS 143028 is inoculated in 200 ml of a preculture medium at pH 5.5 containing a defined mineral composition containing KCl 0.5 gr/L; KH.sub.2PO.sub.4 4, Na.sub.2HPO.sub.4 1.1, Citric acid 1.5 gr/L, MgSO.sub.4.7 aq 2 gr/L, FeSO.sub.4.7 aq 0.1 gr/L, CaCl.sub.2).2 aq 0.1 gr/L, ZnSO.sub.4.7 aq 0.125 gr/L, MnCl.sub.2.4 aq 0.012, CuSO.sub.4.5 aq 0.0016 gr/L, CoCl.sub.2.6 aq 0.0015 gr/L, Na2B.sub.4O.sub.7.10 aq 0.009 gr/L KI 0.0009 gr/L, Na.sub.2MoO.sub.4.2 aq 0.0015 gr/L; 11 g Dextrose per l as C-source; 4 g (NH.sub.4).sub.2SO.sub.4 per l as N-source; and 7.5 g tartaric acid per l. The culture is incubated for 24 hours at 46° C., in a 1 l Erlenmeyer flask with air permeable stop with baffles, in an orbital shaker at 200 rpm. The preculture is then used to inoculate a pH 3.5 medium containing a defined mineral medium as described above comprising 77 g Dextrose per l as C-source; 1.4 g (NH.sub.4).sub.2SO.sub.4 per l as N-source and supplemented with NH.sub.3 as titrant. Olive oil is continuously being fed. More definitions are described in EP20153414.

[0125] Fermentation broths, having reached a dry matter content ranging from 2 to 5 weight percent, were concentrated using a vibrating sieve to achieve a minimum of 10% (wt.) dry matter. The biomass is then pumped through an in-line heating unit comprising a pipe equipped with a steam injector. Pumping speed, pipe diameter, and temperature were configured in such a way that different residence times at different temperatures were achieved. Systematic screening of parameters allowed the generation of killing curves for various degrees of log.sub.10 reduction, notably fora log.sub.10 reduction of 7 (see FIG. 1A), and fora log.sub.10 reduction of 12 (see FIG. 1B). Data is shown in the table below. Pasteurised samples were conveniently dried in a fluid bed drier (70° C. 10 min).

TABLE-US-00001 TABLE 1 kill kinetics using an in-line pasteurisation unit, showing required time in minutes T (° C.) 7 D 8 D 9 D 10 D 11 D 12 D 60 2280.53 2606.32 2932.11 3257.91 3583.70 3909.49 70 79.27 90.60 101.92 113.25 124.57 135.90 71 57.27 65.45 73.63 81.81 89.99 98.17 72 41.45 47.37 53.29 59.21 65.13 71.05 73 30.05 34.35 38.64 42.93 47.23 51.52 74 21.83 24.95 28.07 31.19 34.31 37.43 75 15.89 18.16 20.43 22.70 24.97 27.24 76 11.59 13.24 14.90 16.55 18.21 19.86 77 8.46 9.67 10.88 12.09 13.30 14.51 78 6.19 7.08 7.96 8.85 9.73 10.62 79 4.54 5.19 5.84 6.48 7.13 7.78 80 3.33 3.81 4.29 4.76 5.24 5.71 81 2.45 2.80 3.15 3.50 3.85 4.20 82 1.81 2.07 2.32 2.58 2.84 3.10 83 1.33 1.52 1.71 1.91 2.10 2.29 84 0.99 1.13 1.27 1.41 1.55 1.69 85 0.73 0.83 0.94 1.04 1.15 1.25 86 0.54 0.62 0.70 0.77 0.85 0.93 87 0.40 0.46 0.52 0.58 0.63 0.69 88 0.30 0.34 0.39 0.43 0.47 0.51 89 0.22 0.26 0.29 0.32 0.35 0.38 90 0.17 0.19 0.21 0.24 0.26 0.29

Example 2—Organoleptic Qualities of Pasteurised Single-Cell Protein

[0126] Pasteurised biomass obtained as described above was subjected to analysis by a testing panel. Sample 1 was pasteurised at 74° C. for 37 minutes. Sample 2 was pasteurised at 86° C. for 1 minute. Sample 3 was not pasteurised.

[0127] A testing panel of 12 people reported the following scent sensations for sample 1: metallic, ferric, oxidised, French fries, sunflower oil, raw egg. Samples 2 and 3 were generally described as odourless. Mean marks awarded for scent were 51% for sample 1, and 86% for samples 2 and 3.

Example 3—Organoleptic Qualities of Pasteurised Single-Cell Protein

[0128] Biomass produced as described in example 1 but in the end freeze dried biomass was either pasteurised in a batch manner (sample 1), or with an inline steam injector (samples 2, 3 and 4). Sample 5 and 6 were not pasteurized, the latter was the only sample without an antioxidant mixed in. Samples (1-5) contained 2000 ppm of the anti-oxidant NaturFORT™ 15L from Kemin (www.kemin.com). The temperature/residents time during pasteurisation, was 1 minute 86° C. for sample 1 and 2, 3 seconds at 96° C. for sample 3 and 0.5 seconds at 105° C. for sample 4. The test panel, consisting out of 8 people identified the not pasteurized samples as least pleasant based on smell. The sample pasteurized batch-wise was ranked worst of the pasteurized samples. The sample pasteurized with in the inline steam injector at 96° C. was ranked best followed by the 86° C. sample, the 105° C. sample was ranked third as shown in Table 2.

TABLE-US-00002 TABLE 2 Ranking of different forms of (pasteurized) biomass by an organoleptic test panel of 8. The pasteurized samples all showed a CFU/g (colony forming unit(s))of <10. Anti- Rank (#) based Sample Treatment oxidant on Smell 1 batch pasteurized 1′ 86° C. + 4 2 inline pasteurized 1′86° C. + 2 3 inline pasteurized 3″ 96° C. + 1 4 inline pasteurized 0.5″ 105° C. + 3 5 not pasteurized + 6 6 not pasteurized − 5