| China is a major producer and consumer of edible fungi.In 2018,the total output of edible fungi reached 38.42 million tons,accounting for 76% of the world’s total output.The rapid development of edible fungi industry has made an important contribution to the income increase of farmers,the enrichment of rural areas,the enhancement of agricultural efficiency and the improvement of national health level.Lentinus edodes is one of the most productive edible fungi in China,with an annual output of 10.43 million tons in 2018.L.edodes is rich in nutrients and active ingredients such as polysaccharides,dietary fiber,proteins,amino acids,mineral elements,vitamins,phenols,ergosterol,etc.It also has various physiological functions such as enhancing immunity,anti-tumor,anti-oxidation,anti-inflammatory and anti-virus.For the delicious taste and high nutritional value,L.edodes is very popular in Chinese diet.In this paper,the effects of cooking and processing methods on the nutritional content,bioavailability and antioxidant activity of L.edodes were studied.The aim is to provide theoretical basis for scientific cooking,processing and eating of L.edodes.The main conclusions were summarized as following:(1)The L.edodes were cut into 1.0 cm×1.0 cm×0.5 cm pieces and heated in boiling water for 10,30,60,90 and 120 min,respectively,to study the effects of boiling time on the nutritional components and antioxidant activities of mushroom pieces and soup.The results showed that the contents of polysaccharide,dietary fiber,protein,free amino acids and total phenols in L.edodes pieces decreased with the extension of boiling time during 10-30 min,and tended to be stable after 30 min.Their contents were 93.01 mg/g,329.60 mg/g,227.13 mg/g,1.41 mg/g and 1.51 mg/g,respectively.The content of ergosterol in the L.edodes pieces increased continuously with the prolongation of boiling time,and reached the maximum value when the boiling time was 120 min,which was 2.73 mg/g.The contents of nutritional components inL.edodes soup increased with the extension of boiling time,and reached a high level when the boiling time was 60 min.At this time,the content of polysaccharide in L.edodes soup was 59.19 mg/100 mL,protein content was 72.33 mg/100 mL,free amino acid content was 1.86 mg/100 mL,total phenol content was 4.80 mg/100 mL,but the ergosterol was not detected in L.edodes soup.The DPPH,ABTS and hydroxyl radical scavenging activities and reducing power of L.edodes pieces were relatively high.During the boiling period,the DPPH and hydroxyl radical scavenging activities of L.edodes pieces remained at a relatively high level(> 70%),but the ABTS radical scavenging activity and reducing power declined in the first 30 min,and then tended to be stable.The DPPH,ABTS and hydroxyl radical scavenging activities and reducing power of L.edodes soup increased with the prolongation of boiling time in the first 60 min,and decreased to different degrees after 60 min.Overall consideration,it is recommended that the boiling time of L.edodes should be controlled within 30-60 min.The mushroom soup contains many nutrients and antioxidant activities,so the soup had better be recycled and utilized.(2)The L.edodes were cut into pieces of 1.0 cm×1.0 cm×0.5 cm size and processed with boiling,microwaving,steaming,autoclaving and frying,respectively.The effect of cooking and processing methods on the nutritional components,bioavailabilities and antioxidant activities of L.edodes was investigated.The results showed that the contents of polysaccharide,dietary fiber,protein and total phenol,the DPPH radical scavenging activity and reducing power of L.edodes were significantly reduced after boiling,frying and microwaving treaments,while the contents of these nutrients and antioxidant activities were well retained or even enhanced after steaming and autoclaving treatments.Steaming increased the content of polysaccharide by 5.58%,while microwaving,frying and boiling reduced the content of polysaccharide by 6.82%,14.10% and 22.20%,respectively.Steaming and autoclaving increased thedietary fiber content of L.edodes slightly,while microwaving,frying and boiling reduced the content by14.88%,19.17% and 19.72%,respectively.All the five methods reduced the protein content of L.edodes,among which the protein content lost 25.02% and 26.63%,respectively for boiling and frying treatments.Steaming and autoclaving increased the total phenol content by 14.08% and 15.92%,respectively,while boiling,frying and microwaving significantly reduced the total phenol content.The ergosterol content of L.edodes increased by 30.22% after boiling treatment and decreased by 24.00% after frying treatment,but the other three treatments had no significant effect.The effect of cooking and processing methods on the antioxidant activities of L.edodes was significantly correlated with the change of total phenol content.The results of simulated gastrointestinal digestion model in vitro showed that the bioavailabilities of polysaccharides,proteins and total phenols in L.edodes were significantly increased by all the five cooking and processing methods.Boiling had the best effect on improving the bioavailabilities of protein and total phenols(55.06% and 84.96%,respectively),while autoclaving had the highest effect on improving polysaccharide(47.27%)in L.edodes.Environmental scanning electron microscope(ESEM)observation showed that after cooking,the dense tissue structure inside L.edodes was destroyed,and the cell wall became loose and even cracked,leading to the denaturation and loss of nutrients in L.edodes.From the view of nutritional value and antioxidant activity retention,steaming and autoclaving treatments are better.For boiling treatment,it is appropriate to reduce the amount of water added,and it is suggested to recycle the mushroom soup.(3)Fourier transform infrared spectroscopy showed that the polysaccharides in L.edodes contain the component of acid polysaccharides with pyranoglycosides.The infrared spectra of polysaccharides did not change significantly after cooking.Gel permeation chromatography(GPC)detection showed that the polysaccharides in L.edodes contained five fractions with molecular weights of 399.12 kDa,33.87 kDa,6.27 kDa,3.48 kDa and 1.30 kDa.After cooking,the peak value of GPC did not change significantly,but the content of each fraction changed.Gel filtration chromatography(GFC)was used to study the release and molecular weight changes of polysaccharides of L.edodes in vitro during simulated gastrointestinal digestion after cooking and processing.The results showed that in vitro simulated gastric digestion and intestinal digestion,the disaccharide was the primary carbohydrate released from L.edodes after boiling,microwaving and steaming,and the monosaccharide was the primary carbohydrate after autoclaving and frying.In the dialysis fraction,the carbohydrate released from L.edodes after different cooking processes were mainly monosaccharide. |
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