Effect Of Perill Frutescens Leaf And Its Extract On Quality Changes Of Fried Surimi-based Food During Processing And Cold Storage

The surimi-based product is a traditional food in our country.It is a kind of low fat and high protein food,and it is deeply favored by consumers.However,there are problems in the manufacturing,transportation and storage links of surimi-based food,such as fat oxidation,protein oxidation and microbial contamination,which will reduce the nutritional value and quality of surimi-based products and affect their shelf life.As people pay more attention to food safety issues and have higher requirements to the health,they are worrying about synthetic food additives for their potential health risks and toxicity.Therefore,it is important to search for natural and effective ingredients with similar function to replace synthetic food additives.Perilla frutescens can be used as both food and medicine.It has been found that Perilla frutescens leaves contain various active ingredients,including essential oil,phenolic acids,flavonoids,triterpenes,anthocyanins and glycosides.So it shows antibacterial,antioxidant,and antitumor effects.The main purpose of this study is to explore the effect of Perilla frutescens leaves and its extracts(crude polyphenol,essential oil)on the quality of fried surimi-based food during manufacturing process and cold storage.First,the volatile oil and crude polyphenols of Perilla frutescens leaves were extracted by steam distillation and hot ethanol extraction method,respectively.Volatile components in essential oil and polyphenol monomers in crude polyphenols were determined by solid-phase micro-extraction gas chromatography-mass spectrometry(SPME-GC-MS)and high performance liquid chromatography(HPLC),respectively.Then the antioxidant activity in vitro and antibacterial activity of the essential oil and crude polyphenols were measured.Based on the results of antioxidant and antibacterial activity,the appropriate additive amount of essential oil and crude polyphenols to surimi were selected.Finally,the crude polyphenols,essential oil and Perilla frutescens leaves powder were added to surimi to make fried surimi-based food according to the proportion of the following,0.01% crude polyphenol,0.03% crude polyphenol,0.01%essential oil,0.03%essential oil,0.05% Perilla frutescens leaves powder,0.1% Perilla frutescens leaves powder,and these six groups were treatment groups.The control was made without additives.The surimi-based food was air packed and stored at 4°C for 4 weeks and quality changes were analyzed at one week interval.The color,texture,sensory score,fat oxidation,protein oxidation,T-VBN value and microbial indicators is the seven indexes of quality evaluation of fried surimi-based food.The main results for this study are as follows:1.In our experiments,we found that 100 g of dried P.frutescens leaf powder could gain 0.48 mL of essential oil by steam distillation,and volatile oil yield reached 0.48%.While the polyphenol extraction rate was 20.75 ± 0.90mg/g P.frutescens leaf powder,the total phenol content reached 471.4 ± 5.6 mg/g extract,which show the effect of hot ethanol extraction method is good.Based on the GC-MS analysis,a total of 22 volatile compounds were identified in Perilla frutescens essential oil.Among the 22 volatile compounds,the most abundant compound was perilla aldehyde,content about 23.23%,followed by limonene(19.55%),caryophyllene(14.48%).Five monomeric phenols in the crude polyphenol were measured,containing caffeic acid,ferulic acid,rosmarinic acid,quercetin,apigenin,which rosmarinic acid is the highest,reaching 29.524%.2.The antioxidant capacity of crude polyphenols is stronger than volatile oil,and the ability to remove DPPH· and ABTS+· of per gram crude polyphenols is 455.14 and 378.78 mg Vc equivalent,respectively.The DPPH· and ABTS+· scavenging ability of 15.00 μg/mL crude polyphenols is more than 80%.While the volatile oil has weak antioxidant capacity,The DPPH· scavenging ability of 7mg/mL volatile oil is more than 80%,and the ABTS+· scavenging ability of 2mg/mL volatile oil is more than 80%.The antibacterial effect of volatile oil is good,which the inhibition rate of 0.02% volatile oil against E.coli and Salmonella can reach 50%and the inhibition rate against Staphylococcus aureus is about 20%.0.2% volatile oil can completely inhibit the growth of E.coli,Salmonella and Staphylococcus aureus.But 0.2% crude polyphenols slightly inhibit the growth of Salmonella and Staphylococcus aureus.3.Adding 0.03% Perilla frutescens leaf essential oil can improve the color of fried surimi-based food.The Perilla frutescens leaf crude polyphenols have no significant effect on the color of fried surimi-based food,but Perilla frutescens leaf powder has a bad effect on the color because its own color is darker,especially the 0.1% Perilla frutescent powder group.For the texture,the hardness of the treatment group had a small change during the storage.However,the hardness of the control group was significantly reduced,and there was no significant difference in springiness between all groups.The crude polyphenol group had no negative effect on the sensory score of fried surimi-based food.However,the aroma score of the volatile oil group is lower because essential oil has strong smell,resulting in a lower overall acceptance score.The color score of Perilla frutescens leaf powder is lower,which is consistent with the color result measured by the Chroma Meter.4.The crude polyphenol,essential oil,and Perilla frutescens leaf powder have a certain inhibitory effect on lipid oxidation.The 0.03% crude polyphenols group has the best inhibitory effect.This may be owed to the antioxidant capacity of Perilla frutescens leaf crude polyphenol.Perilla frutescens leaf and its extracts also have a certain inhibitory effect on protein carbonylation.0.03% of the essential oil group had the best inhibitory effect during storage,followed by 0.03% crude polyphenols,and its effect showed dose-dependent.Compared with the control,the Perilla frutescens leaf powder group showed a certain inhibitory effect on protein carbonylation in the early stage of storage,but there was no difference in the later storage.5.In the middle of storage,crude polyphenols,volatile oils and Perilla frutescens leaf powder all had a certain inhibitory effect on T-VBN values.However,the number of microorganisms increased in the later storage,only the T-VBN values of volatile oil group and 0.03% crude polyphenols were inhibited,the effect of volatile oil is obvious during the whole storage period,which has a great relationship with its good antibacterial activity.The volatile oil can inhibit the growth of microorganisms,and the more the amount of volatile oil added,the better the inhibitory effect on microorganisms,can extend the preservation time of 2-3 weeks.While the crude polyphenols and Perilla frutescens leaf powder group can be inhibited the growth of microorganisms in the early storage period,but the inhibition effect on microorganisms is not significant in the middle and late storage period.Based on the above conclusions,crude polyphenols and essential oils from Perilla frutescens leaf could be used in fried surimi-based products to delay quality decline during processing and cold storage,and extend its shelf-life.