Effect Of Tea Polyphenols And Citric Acid On Formaldehyde-Producing During Thermal Processing Of Squid(Dosidicus Gigas) As Well As Their Application In The Dried-Seasoned Squid

Squid resources have topped the list of pelagic fishery production in our country, and the yield and scale have the increasing trend year by year. With rich nutrition and good taste, dried-seasoned squid is very popular in many countries of the worlds. However, much attention has been paid to fonnaldehyde (FA) in squid products, taking into account the potential adverse effects on products quality and human health. Some aquatic processing enterprises suffered huge economic losses due to the high amount of endogenous FA in squid products.In view of these situations, tea polyphenols (TP) and citric acid (CA) as the point of research, the inhibitory property and mechanism of polyphenols extracts and organic acids to FA formation in the non-enzyme pathway of squid (Dosidicus gigas) was assessed. Then compounding TP with CA as FA inhibitor applied into the processing of dried-seasoned squid. Based on this,the effect of vacuum package combining with FA inhibitors on the quality of dried-seasoned squid during storage at25℃was evaluated.1. TP, liquorice extract, resveratrol, propolis and grape seed extract could reduce effectively the generation of FA and dimethylamine (DMA) in the squid supernatant at100℃. Furthermore, five kinds of polyphenols extracts exhibited excellent reactivity with FA. With the increase of TP concentration and the extension of heating time, the thermal conversion of trimethylamine-N-oxide (TMAO) to FA and DMA was suppressed significantly, especially higher than0.15%TP. Similar inhibitory effects of five kinds of catechin monomers form TP on TMAO decomposition were observed. Additionally, TP, ECG and EGCG decrease significantly the formation of free radicals in squid supernatant at high temperature. Therefore, TP could significantly decrease the amount of FA by both repressing the thermal decomposition of TMAO and reacting with the FA, in which catechins played an important role involving in inhibition the thermal conversion of TMAO.2. Succinic acid, oxalic acid, malic acid, tartaric acid, citric acid and trisodiuin citrate could reduce effectively the generation of FA and DMA in the squid supernatant at100℃, whereas six kinds of organic acids exhibited no any reactivity with FA. With the increase of citric acid (CA) concentration and the extension of heating time, the thermal conversion of TMAO to FA and DMA was suppressed significantly, especially higher than5mM CA. And CA depressed greatly the formation of free radicals. Therefore, CA could significantly decrease the amount of FA by inhibiting the thermal decomposition of TMAO. Additionally, similar inhibitory effect of FA formation was observed between0.05%TP combined with5mM CA and0.05%TP sample.3. The moisture, crude protein, crude fat, pH and reducing power of dried-seasoned squid decreased gradually and significant browning happened during the storage, especially the reduction of moisture. The appearance of color had a significant difference in the TP sample compared with control. The treatment of0.15%TP,0.05%TP+5mM CA,0.05%TP+5mM Ca2+in the processing could inhibit significantly the production of FA and DMA from TMAO, and reduce effectively the accumulation of TBA and TVB-N in dried-seasoned squid during the storage. Additionally, the decomposition of lactose into galactose and glucose was observed. So it was suggested that the decomposition of lactose could have a positive correlation with the breakdown of TMAO during the storage.4. Compared with the air package, vacuum package can significantly reduced water loss, protein degradation, inhibition of the Maillard reaction and conversion of TMAO to DMA and FA during storage. The treatment of0.15%TP,0.05%TP+5mM CA in the processing could significantly inhibit the production of FA and DMA, and effectively reduce the accumulation of TVB-N in dried-seasoned squid during the storage. The color of dried-seasoned squid was different significantly for0.15%TP compared with the control sample. However, citric acid can inhibit browning. Therefore, the vacuum package combining with compound FA inhibitor of0.05%TP+5mM CA could effectively keep the quality and inhibit TMAO breakdown to FA and DMA during storage of dried squid.