Study On Nutrient Profiles,Browning Mechanism And Inhibition Of Three Wasp Larvae

Wasp?Insecta: Hymenoptera: Apocrita?is the general name for Vespoidea insects.Wasp larvae have high nutritional value and medicinal health care value,and have broad prospects for development and utilization.However,the nutrient profiles of most wasp larvae are not clear at present,and the cause of browning during processing and transportation is also unclear.Therefore,in this paper,the nutrients and nucleotide content of Apoica pallens,Vespa mandarinia Smith and Vespa velutina Lepeletier larvae were examined,and the browning type of the three wasp larvae were identified,then the activity of polyphenol oxidase in the three wasp larvae was inhibited by ascorbic acid and ultrahigh pressure.It provides a theoretical basis for the development and utilization of wasp larvae products in the future.The main results of this paper include the following four parts:?1?The nutrient profiles and nucleotides of three wasp larvae were analyzed by using the national standard method.The results showed that the crude protein content?%?was 53.47,56.36 and 51.29 respectively;the crude fat content?%?was 21.98,20.53 and 22.96respectively;the iron content?mg/100 g?was 10.63,10.90 and 10.11 respectively;the zinc content?mg/100 g?was 8.370,9.550 and 7.170 respectively;the selenium content?mg/100 g?was 0.017,0.020 and 0.015 respectively;the content of vitamin E?mg/100 g?was 2.477,2.377 and 2.535 respectively;the content of vitamin B1?mg/100 g?was 0.174,0.125 and 0.211respectively;the content of vitamin B2?mg/100 g?was 2.235,2.082 and 2.291 respectively;the ratio of essential amino acids to total amino acids?EAA/TAA?was 0.360,0.361 and 0.370respectively;the ratio of essential amino acids to non-essential amino acids?EAA/NEAA?was0.563,0.565 and 0.590 respectively;the ratio of polyunsaturated fatty acids to saturated fatty acids?PUFA/SFA?was 0.260,0.267 and 0.263 respectively;the ratio of n-6/n-3polyunsaturated fatty acids?n-6/n-3 PUFA?was 0.863,0.994 and 0.803 respectively;the content of hypoxanthine nucleotides?IMP?was much higher than that of guanine nucleotides?GMP??p<0.05?.?2?Ultraviolet spectrophotometry was used to scan the crude enzyme solution of threewasp larvae at full wavelength,and the results showed that the maximum absorption wavelength was 290 nm,288 nm and 287 nm,respectively.Then the protein in the crude enzyme solution was removed by alkali solution and acid precipitation method,and the browning degree of the supernatant solution remained unchanged for 12 hours.The above results indicated that larvae browning was related to protein,and was enzymatic browning.Furthermore,a variety of proteins were isolated from the crude enzyme solution by using Native PAGE and non-reducing SDS-PAGE electrophoresis techniques,and browning bands were selected by L-DOPA activity staining.Finally,the browning bands were identified by LC-MS,and the results showed that the browning bands of three wasp larvae contained the same protein,which was phenoloxidase 2-like of Polistes Canadensis,with the molecular weight of 80.1 and the sequence number of XP₀14613622.1.?3?Effect of ascorbic acid on PO of three wasp larvae.The IC50 value of PO inhibition by ascorbic acid on three wasp larvae was 0.2277,0.2626 and 0.2319%?w/w?,respectively.When the added amount of ascorbic acid reached 0.5%?w/w?,the inhibition rate of PO on Apoica pallens and Vespa mandarinia Smith larvae reached 96.61% and 93.2%,respectively,and the inhibition rate of PO on Vespa velutina Lepeletier larvae reached 100%.?4?Effect of ultrahigh pressure on PO of three wasp larvae.In terms of pressure,no matter whether the holding time was set to 5 min or 15 min,as long as the pressure was in the low range?100 MPa-200 MPa?,the PO activity of the three wasp larvae was not passivated,but has a slight promotion effect.With the holding time of 5 min,PO activity can be effectively suppressed when the pressure reached 400 MPa or more.With the holding time of 15 min,PO activity can be effectively suppressed when the pressure reached 300 MPa.In terms of holding time,the PO activity of three wasp larvae decreased with the prolonging of holding time under the pressure of 300 MPa.However,when the time reached 15 min,the PO activity of Vespa mandarinia Smith larvae was further inactivated without obvious effect.When the time reached10 minutes,the PO activity of Apoica pallens and Vespa velutina Lepeletier larvae was further inactivated without obvious effect.