Microwave heating and conduction heating pork belly: Influence of heat transfer modes on volatile compounds and aroma attributes

This work was conducted to compare the differences in odor attributes and the formation causes of pork belly cooked by different heating modes and the feasibility of achieving convenient and delicious cooking of stir-fried pork cuisines by modifying the heat transfer mode of the microwave.The effects of traditional pan-heating(TH),microwave heating(MH),and microwave combined with conduction heating(MH+CH)on sensory aroma attributes,aroma profile,free fatty acids,and volatile compounds of pork belly were investigated.The results showed that the pork belly heated by TH had the lowest total amount of stable volatile compounds(1695.41μg/kg)and contents of free fatty acids(751.44 mg/100g),but the balanced distribution and the rich contents of volatile compounds derived from thermal processing resulted in the better aroma quality of pork belly.In contrast,although the pork belly cooked by MH had higher free fatty acids contents(1215.32 mg/100g)and the highest volatile compounds(5410.56μg/kg),due to the cell destruction effect and the molecular movement acceleration of microwave,the contents of volatile compounds derived from spices were too high,leading to the disharmony of aroma characteristics.However,the pork belly cooked with MH+CH not only promoted the production of free fatty acids(1434.23 mg/100g),but also increased the generation and retention of pork characteristic aroma by changing the heating modes.Compared with MH,it enhanced the uniformity of aroma distribution and improved the overall aroma similarity to TH.

Accurate pH decrease induced inactivation of myrosinase and polyphenol oxidase in salted radish for color improvement

Yellowing even browning of radish commonly occurred during the traditional pickling.This research aimed to determine the reason of yellowing of pickled radish,and propose the method for yellowing inhibition.The activity of endogenous enzymes in radish were analyzed,and the relationship between the activity and the browning was investigated.Myrosinase and polyphenol oxidase(PPO)were found as main potential enzymes resulting in browning of radish.During traditional salting processing,the myrosinase activity decreased,particularly at a high speed in the first 14 days,while the PPO activity did not decrease observably.The a*and b*values of salted radish were significantly correlated with myrosinase and PPO activity.Acid treatment was observed to be effective for browning inhibition of radish during soaking and storage,and the low pH conditions contributed to the preservation of original green color of radish.Stronger acidification during the first 3 d played a much more important role in browning inhibition than following weaker acidification treatment for 27 d.Low pH showed an inhibition effect on PPO activity,but myrosinase reactivity was more sensitive to pH changes than PPO.The myrosinase in the radish treated in the pickling solution at pH 2 was completely inactivated during the first 3 days.Further investigation of pH effect on improvement of salted radish color concluded that pH 2.4 was the optimal pH for the inactivation of myrosinase and PPO.Accordingly,short-term accurate acidification coupled with traditional salting treatment was originally proposed for effective browning inhibition of pickled radish.

Functional biochar for efficient residue treatment of sulfonylurea herbicides by weak molecular interaction

Pesticide residues have seriously damaged the natural environment and social security.Here,we prepared the efficient functional biochar(FB)for sulfonylurea herbicides from cotton straw cellulose(CSC)by hydrothermal carbonization with the methacrylic acid.The molecular simulation of FB indicated thatπ-πelectron-donor-acceptor(EDA)interaction and formation of charge-assisted H-bond were both the main factors for effective adsorption process.The adsorption process can match the pseudo-second-order kinetic equation and Freundlich model.The whole process is physical adsorption,spontaneous and rapid,and can quickly reach equilibrium.The FB with carbon-oxygen functional groups and aromatic conjugated structures can remove pesticides in water very quickly(within 30 s),with effective adsorption over 95%of Sulfonylurea herbicides(SUHs).Therefore,functional FB might be an effective way to get excellent absorbent for pesticide treatment.