Black Soldier Fly as Fish Food- Do Resulting Fish Have a Different Flavor?

Hello Everyone- I hope this Monday finds you well and you are well rested after a great weekend. My weekend was very relaxing; fall is surely here. We had a cold front with the temperatures dropping to 33°C (believe me, this is a cold front for Texas).
 
I will be traveling this week so my blog posting might be a bit off schedule come the middle of the week. But I will do my best to make sure to have something interesting posted by Wednesday or Thursday. 

On to the next topic.....
 
I am going to switch gears for the next few posts and focus on animal production when using BSF as a feed ingredient. But, before I do, I thought I would tackle a subject that is of great importance to the industry as well- if we can produce animals by feeding them BSF, does the flavor (based on consumer response) of the animal change?  In fact, there is limited information on this topic- which means there is ample opportunity for additional research.
 
The one paper I am aware of (please let me know if there are others as I would love to read them and discuss them with you) is a paper published six years ago. The title is:
 
Sensory Analysis of Rainbow Trout, Oncorhynchus mykiss, Fed Enriched Black Soldier Fly Prepupae, Hermetia illucens
 
Overview: This study was done as a follow-up to a previous study published by Sophie St. Hilaire (to be reviewed in a future blog) who is also an author on this particular paper. The major question was- if you feed fish BSF, will people consuming them find them palatable?  This question is very important when you consider most countries in the world have approved BSF as a feed ingredient for the aquaculture industry (select species of course).
 
Synopsis:  The researchers in this study used rainbow trout, Oncorhynchus mykiss, as its model. The authors replace the fishmeal diet with 25% and 50% BSF or fish offal-enriched BSF prepupae. The fish were fed the diets for eight weeks prior to harvesting and use in the “taste test.” They also measured growth of the fish on these diets. They determined diet did impact growth rate. Those fed the fish offal-enriched BSF diet grew slower (16%), but not significantly, than those in the control; however, those fed strictly BSF replacement (25% replacement about 31% smaller; 50% replacement about 25% smaller) diet had significantly reduced growth rate. While the growth analysis was not the most positive, there results from the taste test were- basically 30 untrained people tried the fish produced from the three diets and determined no difference in flavor!
 
Details….details…details…..of the study, if you would like to know them J
 
This paper is has a nice component with regards to nutritional analysis of the resulting diets (including the BSF used in the study). These results are presented in Tables 1-4. Table 1 presented amino acid composition of the BSF diets. Table 3 provides a more gross description of the diets used in the study. Components include fishmeal, corn gluten meal, and much more. In table 2 and 4, you will notice that there are some differences in fatty acid composition across the diets. Such data are important when formulating industry grade diets as consistency in nutrient makeup is critical for consistent production in aquaculture. Furthermore, by knowing these data, nutritionists can formulate a diet resulting in optimal aquaculture production as well.
 
Other data related to feed conversion, feed consumption, muscle ratio, and more are presented in Table 5.

Conclusions: The basic conclusions from this study are the replacement of fishmeal with BSF or enriched BSF impacted growth of rainbow trout; however, such replacements did not impact flavor. The consumer had no problem with the flavor of the fish produced on a partial BSF diet. So what do these data mean?

1. More work is needed to determine how to optimally produce rainbow trout on BSF replacement diets.
2. Using BSF as replacement for standard rainbow trout diets does not impact the flavor of the fish produced.
3. Such studies should be conducted on other fish species to determine if these results hold true.

 
 As always, I hope this information is interesting and useful. My plan, as I mentioned earlier, will be to review other studies where BSF has been used as a feed replacement for livestock, poultry, and aquaculture. And please- if there are other topics you would like me to cover, let me know. Thanks to Cies and Paul for recommending topics. I promise, these will be covered soon.
 
Until next time- all the best and happy BSF farming!

Author

Jeff Tomberlin, PhD, BSF nutritionist?
Twitter: @FliesFacility
Director, EVO Conversion Systems
evoconsys.com