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Cricket flour "fishy smell"?

Hi all,

The one time I ordered some cricket flour from a local farmer, it arrived with some very strong fishy odour. I couldn't bring myself to try to make food out of it, and ended up throwing it out.

Is this fishy smell normal for cricket flour?

Secondly, where can I find good references for processing live crickets to cricket flour please?

Regards, Octavius

Comments

  • Hi octavius, - Since I do not make cricket flour the following is my conjecture only. There are in all likelihood more than one factor generating your strong odour.

    Bug gut symbiotic (& non-symbiotic) bacteria export protein degrading enzymes (prote-ase) that act outside (extra-cellular) their bacterial cell walls; these enzymes have metal ion cores which causes them to be reactive. Such metallo-prote-ase vary in their activity & one factor is that calcium to inter-act with makes them even more stable; thus insect dietary calcium can boost these kind of enzymes capability to alter proteins (proteo-lysis).

    Insects' version of blood & lymphatic fluid called haemolymph (contains proteins) is about 6.5pH but once they are dead the extra-cellular bacterial prote-ase enzymes activity raises the haemolymph compound(s) toward 8 pH; heat curing the bug body may also compound the protein alteration. Anyway from 6 - 7 pH a lot of proteo-lysis occurs with the maximum of this type of action found at 8 pH; & since chemical reactions are not linear at 9pH proteo-lytic activity of extra-cellular bacterial prote-ase (enzyme) drops to over 1/2 what it would be at 8pH (likewise, at 10 pH there is less proteo-lysis than at 6-8 pH).

    At lower than 9pH there is an easier de-naturing (altering) of certain proteins when it is subjected to heat; those proteins with bio-chemistry that are stably packed (folded) tight in higher pH get looser packed (reactive center opens) at lower pH. Thus an otherwise non-reactive protein of the dead insect can unfold to let the naturally (or not) occuring microbes' de-grading enzyme's catalytic part access to parts of an insect protein scaffolding that had until then (right pH/temperature) been hidden from enzyme access due to the way that protein had been folded. Probably changing heat application from oven drying to pressure heating (ex: auto-clave) would be a better tactic since there would be less protein de-naturing when heat treatment performed.

    My assumption is the disagreable odour from protein breakdown is ammonium sulfate, di-alpha-amine & di-methyl-sulfide. I expect different cricket meal batches to vary in odour; in part due to post-euthanasia handling. Disinfection would probably help prior to dessication; since method used to kill the insect may not kill it's internal bacteria. Bear in mind that even once heat begins to be applied this does not immediately inactivate enzymes those bacteria have already secreted even if it inactivates the bacterial cell. For commercial operations consider that the metal chelator EDTA is capable of chelating (locking up) the metal of metallo-protein-ase enzymes (ie: extra-cellular bacterial prote-ase enzyme) in amounts of 1 - 2 mMol per Mol enzyme.

    Other odour constituents can include: 3-methyl-1-butanol; 2, ethoxyethyl acetate; 2,5-dimethy pyrazine; assorted methoxy pyrazines; 2-nonanine; benzaldehyde; iso-valeric acid; 1-hexanol; phenylethylamine; triethanolamine; n-valeric acid; n-caproic acid; n-caprylic acid; n-butyric acid; phenols; and verbenene (from yeast or terpene alpha-pinene insect got in food; ingesting this terpene inhibits insects from hanging out together). One factor worth mentioning is that the insect exo-skeleton's cuticle has fatty acids & these break down as well after death (oleic acid status of dead bug is often trigger for colony member to eat it). Linoleic acid is a very stable long chain fatty acid that has a really low vapor pressure, so it doesn't volatize (evaporate away) readily leading to it's relative % going up in the carcase (vs. other lipids) - especially once deliberate heating performed; which I think creates part of the funky fish bouquet.

  • Thanks for this! Now, how to make cricket flour safe and good for further processing into food for human?

  • Crickets are arthropods. Also in the arthropod family are shrimp, lobster and crab.. smells fishy to me. Detailed tasting notes can be found here thefutureofedibleinsects.com/2016/01/31/cricket-powder-tasting-notes/ and general processing parameters here thefutureofedibleinsects.com/2014/09/14/how-are-crickets-processed-and-used-as-food-cricket-flour/

  • @Mark thanks for sharing here

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