| Plastic-based synthetic materials are widely used in traditional food packaging,which has been linked to environmental pollution and some health risks.Therefore,many natural edible substances were used to create biodegradable and active intelligent materials that can be used as alternatives to them.Biomolecule-based packagings are usually made from natural,biodegradable,and nontoxic polymers.Active intelligent packaging materials can be obtained by adding natural pigments,antibacterial agents or antioxidant active substances to biomolecule-based packagings.The dynamic changes of food quality can be observed in the process of transportation,storage and consumption.The pH indicator films is an important smart packaging materials because that its color alteration indicates food decay and external environment change.The purple sweet potato contain abundant anthocyanins.As an important natural colorant,anthocyanins having antioxidant and antibacterial effects,can be prepared functional films with good pH sensitive property.It has a relatively high economic value.In order to extend the industrial chain of purple sweet potato in Sichuan Province and improve the economic benefits of farmers,we developed the extraction process of anthocyanin in purple sweet potato and explored the application of new pH indicator film in meat products.In addition,it is one of the important woody oil plant crops in China,with a wide planting area in Sichuan Province.However,there are few literature reports for the Idesia polycarpa Maxim.Oil.We study the flavor and storage of Idesia polycarpa Maxim.Oil.The main research contents are as follows:(1)Study the extraction technology of anthocyanin from purple sweet potatoWe studied the extraction technology of anthocyanin from purple sweet potato by ethanol solvent(containing 0.1% citric acid).The influence of main factors(ethanol concentration,solid-liquid ratio,extraction time and extraction temperature)on anthocyanin yield of purple sweet potato was analyzed,and then the orthogonal experiment with four factors and three levels was used to optimize the study.The purpose was to select the best conditions for extraction of anthocyanin from purple potato,so as to use anthocyanin as food colorant.The results showed that the optimal extraction conditions(35.2 mg/g)were solid-liquid ratio 1∶10(g/m L),extraction temperature 60℃,ethanol concentration 40%,extraction time 6 h.(2)Preparation of the novel pH indicator films and its application in fish freshness monitoringA new pH indicator films based on chitosan(CS),hydroxypropylmethylcellulose(HPMC),ε-polylysine(ε-PL)matrix by incorporating purple sweet potato anthocyanins(PSPA)through solvent casting method,has been developed.The Fourier transform infrared spectroscopic(FT-IR)of the films showed that PSPA was added to CS/HPMC/ε-PL matrix.The scanning electron microscopic(SEM)image and X-ray diffraction(XRD)spectra indicated that PSPA was well blend in CS/HPMC/ε-PL-matrix.The light transmittance rate and moisture contents(MC)of the films decreased by adding PSPA and ε-PL.Adding an appropriate ε-PL,the antimicrobial properties can be improved.When the fish became spoiled,the color of the film was changed from red to green,and the total volatile basic nitrogen(TVB-N)content was higher than that of Chinese Standard GB 2733-2015 at 36 hr.Therefore,the novel pH indicator films could be applied in monitoring and packaging the freshness of fish.(3)The effect of refining on the volatile flavor of Idesia polycarpa Maxim.OilWe mainly used Idesia polycarpa Maxim.fruit as raw material to extract crude oil by cold pressing method,and refined oil was obtained by using the previous research method of our research group.After refining the physical and chemical indexes of Idesia polycarpa Maxim.Oil are approach the national standards.Then,headspace solid-phase microextraction combined with gas chromatography-mass spectrometry(HS-SPME-GC-MS)was used to detect and analyze the volatile flavor components and their contents in the crude oil and refined oil samples of Idesia polycarpa Maxim.68 volatile components were detected.Among them,7 kinds of acids,6 kinds of esters and 13 kinds of hydrocarbons were found in Idesia polycarpa Maxim.crude Oil.After refining,7 kinds of acids,3 kinds of esters and 10 kinds of hydrocarbons were detected in the refined oil of Idesia polycarpa Maxim.Oil.Phenols,aldehydes and alcohols were significantly reduced.(4)Study on the influence of storage conditions on the quality of Idesia polycarpa Maxim.OilUnder different storage conditions,the AV value,POV value,p-AV and CDV value of Idesia polycarpa Maxim.Oil.increased with the extension of storage time.These values increase significantly under high temperature,light and plastic bottle packaging.However,the physicochemical indexes of storage in low temperature,dark,brown glass bottle packaging and antioxidant conditions are relatively lower.There was no significant difference in the storage of fatty acids,indicating that the oil was not easy to be oxidized in a short time.Therefore,it is concluded that the most suitable storage conditions for Idesia polycarpa Maxim.Oil and refined oil are as follows: adding tert-butylhydroquinone(TBHQ)antioxidant,packaging in brown glass bottles,and storage at low temperature at 4℃,away from light. |
PDF Full Text Request