Biodegradation of waste refrigerator polyurethane by mealworms

Refrigerator insulation replacement results in discarding a large amount of waste refrigerator polyurethane(WRPU).Insect larvae like mealworms have been used to biodegrade pristine plastics.However,knowledge about mealworms degrading WRPU is scarce.This study presents an in-depth investigation of the degradation of WRPU by mealworms using the micro-morphology,composition,and functional groups of WRPU and the egested frass characteristics.It was found that the WRPU debris in frass was scoured,implying that WRPU was ingested and degraded by mealworms.The carbon content of WRPU-based frass was lower than that of WRPU,indicating that mealworms utilized WRPU as a carbon source.The urethane groups in WRPU were broken,and benzene rings’C=C and C–H bonds in the isocyanate disappeared after being ingested by mealworms.Thermal gravimetric-differential thermal gravimetry analysis showed that the weight loss temperature of WRPU-based frass was 300°C lower than that of WRPU,indicating that the thermal stability of WRPU deteriorated after being ingested.The carbon balance analysis confirmed that carbon in the ingested WRPU released as CO_(2) increased from 18.84%to 29.80%,suggesting that WRPU was partially mineralized.The carbon in the mealworm biomass ingesting WRPU decreased.The possible reason is that WRPU does not supply sufficient nutrients for mealworm growth,and the impurities and odor present in WRPU affect the appetite of the mealworms.The microbial community analysis indicated that WRPU exerts a considerable effect on the gut microorganism of mealworms.These findings confirm that mealworms degrade WRPU.

Improving the nutritional values of yellow mealworm Tenebrio molitor(Coleoptera: Tenebrionidae) larvae as an animal feed ingredient: a review

Yellow mealworm larvae(YML;Tenebrio molitor) are considered as a valuable insect species for animal feed due to their high nutritional values and ability to grow under different substrates and rearing conditions. Advances in the understanding of entomophagy and animal nutrition over the past decades have propelled research areas toward testing multiple aspects of YML to exploit them better as animal feed sources. This review aims to summarize various approaches that could be exploited to maximize the nutritional values of YML as an animal feed ingredient. In addition, YML has the potential to be used as an antimicrobial or bioactive agent to improve animal health and immune function in production animals. The dynamics of the nutritional profile of YML can be influenced by multiple factors and should be taken into account when attempting to optimize the nutrient contents of YML as an animal feed ingredient. Specifically, the use of novel land-based and aquatic feeding resources, probiotics, and the exploitation of larval gut microbiomes as novel strategies can assist to maximize the nutritional potential of YML. Selection of relevant feed supplies, optimization of ambient conditions, the introduction of novel genetic selection procedures, and implementation of effective post-harvest processing may be required in the future to commercialize mealworm production. Furthermore, the use of appropriate agricultural practices and technological improvements within the mealworm production sector should be aimed at achieving both economic and environmental sustainability. The issues highlighted in this review could pave the way for future approaches to improve the nutritional value of YML.

Improving flesh quality of grass carp(Ctenopharyngodon idellus)by completely replacing dietary soybean meal with yellow mealworm(Tenebrio molitor)

In order to find viable alternative protein sources for aquaculture,we evaluated the effect of partial or complete replacement of dietary soybean meal with yellow mealworm(TM)on the flesh quality of grass carp.In this study,180 grass carp(511.85±0.25 g)were fed 3 experimental diets in which 0%(CN),30%(YM30)and 100%(YM100)dietary soybean meal was replaced by TM for 90 d.The results showed that growth performance,biological parameters and serum antioxidant capacity of grass carp were not affected by dietary TM(P>0.05).Both muscle and whole body crude protein were obviously promoted with the increase of dietary TM(P<0.05),and the concentration of heavy metal in muscle was not influenced(P>0.05),indicating that food safety was not influenced by TM.Dietary TM improved muscle textural characteristics by elevating adhesiveness,springiness and chewiness in YM100(P<0.05).In addition,the muscle tenderness was significantly increased by declining the shear force(P<0.05).The muscle fiber density in YM30&YM100 and length of dark bands and sarcomeres in YM100 were obviously increased(P<0.05).The expression of myf5,myog and myhc exhibited a significant upward trend with the increase of dietary TM(P<0.05),which promoted fiber density,length of sarcomere and texture of grass carp muscle.According to the results of metabolomics,the arachidonate(ARA)and eicosapentaenoic acid(EPA)were notably elevated in YM30 and YM100,which indicated that the improvement of flesh quality of grass carp may contribute to the dietary TM influence on muscle lipid metabolism,especially the polyunsaturated fatty acids.In conclusion,TM can completely replace dietary soybean meal and improve the nutritional value of grass carp.

Partial replacement of soybean meal by yellow mealworm(Tenebrio molitor)meal influences the flesh quality of Nile tilapia(Oreochromis niloticus)

This study investigated the effects of yellow mealworm meal(YM)replacing soybean meal(SBM)at different proportions(0%,15%,30%and 45%,referred as YM0,YM15,YM30 and YM45,respectively)on the flesh quality of Nile tilapia.A total of 360 fish(70.0±0.12 g)were randomly divided into 4 groups(3 tanks per group).Fish were fed the experimental diet twice daily for 10 wk.The results showed that muscle protein content significantly decreased in YM30 and YM45,while the lipid content significantly decreased in YM45(P<0.05).The essential amino acids and flavor amino acids of the muscle were not affected by the YM substitution,while saturated fatty acid content decreased in YM30 and YM45 compared with YM0(P<0.05).Fillets in YM45 had higher hardness,gumminess,and a higher proportion of thin myofibers(≤100μm,P<0.05)than those in other groups.Further analysis revealed that apoptosis and atrophy related genes were up-regulated,while the muscle antioxidant capacity decreased significantly in YM45(P<0.05),which may be related to the high acid value in YM45 diet.Our findings indicated that YM could replace up to 30%SBM without substantially altering the flesh quality.When the replacement ratio increased to 45%,the flesh quality would change.Special attention should be paid to avoid feed rancidity which may affect the flesh quality of fish.

Chemical components in yellow mealworm(Tenebrio molitor L.)reared with tea powder

The yellow mealworms(Tenebrio molitor L.)were reared by different ratios of tea powder and wheat bran powder mixtures,and weighted every day during the whole 10 days rearing.The content of tea polyphenols,total catechins,catechin(C),epicatechins(EC),epigallocatechins(EGC),epicatechin gallates(ECG),epigallocatechin gallates(EGCG),and nutrition components such as protein and fatty acid in the yellow mealworms were determined after 10 days rearing.The yellow mealworms can put on weight and grow well when the proportion of tea powder belows 80%,while 100%tea powder rearing has no signifi cantly reduced the weight of yellow mealworms.The content of tea polyphenols,total catechins,C,EC,EGC,ECG,and EGCG all enhance signifi cantly along with the increase ratio of the tea powder.The protein content increase more signifi cantly at 50%and 80%ratios treatments than the other treatments.Tea powder added rearing reduces the content of saturated fatty acid,and has a complex effect on the content of unsaturated fatty acid.Comprehensive analysis of the components determined show that 50%ratio is the best for yellow mealworm rearing.