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Parts of twelve plant species - fruits, leaves and oilseeds – viz Terminalia catappa (Indian almond), Opuntia ficus-indica (Cactus), Carissa carandas (Karanda), Camellia sinensis (Green tea), Camellia sinensis (Black tea), Laurus nobilis (Bay Leaves), Murraya koenijii (Curry leaf), Trachyspermum ammi (Ajwain), Brassica alba (Mustard), Trigonella foenum graecum (Fenugreek) and Papaver somniferum (Poppy) seeds were screened for their total phenolic contents and antioxidant potential by three different methods: DPPH scavenging activity, ferric reducing power and ferrous ion-chelating effects. Among the fruits, the highest polyphenolic contents were estimated in T. catappa and least in O. ficus indica.Among the herbal leaves, the total phenols were estimated in the order:C. sinensis-green > C. sinensis-black > L. nobilis >M. Koenijii. Among the oilseeds used for this study, the highest polyphenol contents were found in ajwain, then in mustard > in fenugreek and least in poppy seeds. DPPH activity, ferric reducing power and ferrous ion-chelating effects were shown by the extracts of all three fruits which confirmed both direct and indirect antioxidant effects of the fruit extracts.Among the three fruits the highest antioxidant potential was shown by T. catappa fruit extract and least by O. ficus indica fruit.Among the herbal leaves tested, the highest antioxidant power was shown by C. sinensis –green (green tea)>C. sinensis-black (black tea)> L. nobilis >M. koenjii.Among the oilseeds, the highest activities were shown by T. ammi (ajwain) then B. alba(Mustard)> T. foenum graecum (fenugreek) and least by P. somniferum (poppy). The antioxidant activities of methanolic extracts were higher compared to the oil fractions of all oilseeds.Antioxidant potential (measured by any of the three methods) of each of Shagufta Ishteyaque 7 the 12 plant extracts was found to be highly concentration dependent and showed a high correlation between concentration and % activity (R>0.96). As a result of screening of all the fruits, herbal leaves and oilseeds, species with highest antioxidant activity were selected for further evaluation of their antioxidant effect inside the food packaging films and as bioactive coatings on the prepared films i.e., T. catappa among fruit, green tea among herbal leavesand ajwain among oilseed. The crude extracts of the above plant parts were fractionatedinto acidic, neutral, anthocyanins and non – anthocyanin polyphenolicfractions which were then screened for their antioxidant activities. The fractions that displayed significant antioxidant potential were added as antioxidants to the base polymer Low Density Poly Ethylene (LDPE) in varying concentrations and the packaging films were then developed from blends by two different methods-namely heat pressing and by extrusion.Pre-manufactured LDPE, High Density Poly Ethylene (HDPE) and Poly Ethylene Terephthalate (PET) films were also used to develop bioactive films using procedures of spray-coating and coating with polyphenol-gelatin mixture (PGM). The resultant films obtained were analyzed for their tensile properties, water vapour permeability (WVP), oxygen transmission rate (OTR), oxygen induction time (OIT), optical properties and antioxidant retention/release in comparison with the control films (films with antioxidant fraction). The total phenolic contents were much higher in neutral fraction compared to acidic in C. sinensis and T. ammi leaves (p<0.01) while much higher amount was estimated in non anthocyanin fraction compared to anthocyanin in T. catappa fruit (p<0.01). Only the LDPE films manufactured by heat press and extrusion processes were tested for change in mechanical strength as the other types were produced by coating of extracts onto prepared films. In case of heat pressed LDPE films,a significant Shagufta Ishteyaque 8 decrease in tensile strength and% elongation (compared to control, p<0.05) was observed at 5% polyphenolic fraction whereas this decrease wassignificant in extruded films even at 2% polyphenolic fraction.The decrease in strength in both types of films seemed to be independent of the type and source of fraction.Compared to control value, elastic modulus increased in extruded films with 2% and 5% polyphenolic fraction but increased only at 5% fraction concentration in heat pressed films. The trend of % haze and % transmittance data for heat pressed and extruded LDPE films were similar in the way that for both type of films % haze and % transmittance values were almost same at 1% and 2% polyphenolic fractions and were significantly different from control value at 5%. However in case of spray-coated films and films coated with PGM, the % haze values even at 1% and 2% polyphenols were higher compared to control. In spray-coated films the haze values at 1% were almost identical to the values at 2% while in films coated with PGM, values at 2% polyphenols were higher than the values at 1%. The same trend was observed in HDPE and PET films coated with PGM i.e. compared to control, the values of haze and transmittance were significantly different at all concentrations of polyphenols in mixture. One trend that was common to LDPE, HDPE and PET films was that irrespective of the process of film making, and irrespective of the plant source used, the values of % haze for the films incorporated with crude extract were higher compared tovalues of the films incorporated with acidic, neutral, anthocyanin or non-anthocyanin fractions of the same species. The incorporation of polyphenols at 1% and 2% level in heat pressed, spray-coated and extruded LDPE films did not affect the WVP of the films but at 5% level Shagufta Ishteyaque 9 significant decline was noted as compared to control. However in case of PGM coated films, the mixing even at 1% and 2% declined the WVP to a significant level compared to control. No significant changes in values of WVP were observed with respect to the nature and source of polyphenolic fraction. Not only the WVP of the coated LDPE films dropped as compared to the controls films but the same effect was also observed in HDPE and PET films. Like WVP, OTR decreased in all four types of LDPE films as a result of incorporation of polyphenolic extracts/fractions as compared to controls. Like LDPE, OTR also declined significantly in PGM-coated HDPE and PET films. OIT tests were performed for all four types of LDPE films but only for the LDPE films made with green tea polyphenols. Compared to control, OIT increased in all types of films. OIT increased with increasing concentration of polyphenols from 1% to 5% which means higher amount of polyphenols incurred greater oxidative stability in the films. In PGM coated films, the binding of polyphenols with gelatin as a support resulted in maximum retention of polyphenols in these films and hence in highest OIT as compared to control. For each of the four types of films, increase in OIT with concentration was maximum in the films incorporated with crude extracts and minimum in the films made with acidic extract. Compared to the amount of total phenols in crude and neutral fractions of the extracts, total phenols were much less in the acidic fraction of all three extracts but still the effect of adding acidic fraction on OIT of the film at 5% level was quite noticeable. The increase in OIT with respect to control value indicates that the polyphenolic extracts or fractions retained their antioxidant activity inside the packaging films. In contrast to other properties of the films like WVP and OTR, OIT not only showed dependence on the concentration of the polyphenols but also on the nature of polyphenols. Further irrespective of the film Shagufta Ishteyaque 10 type and method used to produce the film, oxidative stability of the films increased following addition of the polyphenolic extract or fractions derived from green tea. The study of antioxidant activity retained into or released from the plastic films over a period of 60 days was performed only in heat pressed and extruded LDPE films (at 5% polyphenolics).For both type of films the release of antioxidant from the film after every 10 days was corresponding to the retention of antioxidant activity. Like OIT, the maximum release and retention of antioxidant activity was observed for LDPE films incorporated with crude extract of green tea and least for LDPE film made with acidic fraction. Also like OIT, the antioxidant activity of the extruded film was found to be higher than heat pressed film made with a particular polyphenolic fraction at a fixed concentration. Based on highest antioxidant activity and oxygen induction time only the LDPE films incorporated with green tea extract and fractions (at 5% level) werefurthertested for theirpreserving efficacy forfood products packed into itincluding orange juice and black drum (Pogonias cromis) fish fillet. In each type of film, the greatest protection to vitamin C was offered by crude extract, then neutral fraction and then least by acidic fraction. The loss of vitamin C occurred in all (compared to the value in fresh juice, 56 mg/100 mL) however the loss in control films was quite noticeable as compared to the loss in films containing or coated with polyphenols, among the four types of films, the minimum loss of vitamin C occurred in PGM coated films, then in extruded < in heat pressed films and maximum in spray-coated films. Shagufta Ishteyaque 11 % free fatty acid (FFA) in fish fillet increased considerably in 5 months in controlled LDPE films (from 19±1.50 to 44±1.30) compared to %FFA in fresh fillet (2.06), however the rate of increase in % FFA of the polyphenolics incorporated LDPE films was significantly less than the control irrespective of the type of film and chemical nature of the polyphenols. Among the four type of films, the rise in % FFA was maximum in spray-coated while minimum in LDPE films coated with PGM. For each of the four types of film, highest decline in FFA was observed in the fish samples packed in LDPE containing crude extract of C. Sinensis while least in samples packed in LDPE with acidic polyphenols of C. Sinensis. The peroxide value (PV) increased till 4th month and then decreased in 5th month. As observed in other results, minimum peroxides formation took place in fillets wrapped in PGM coated LDPE while maximum in fillets wrapped in spray-coated LDPE films. Likewise, for a particular type of film, maximum hindrance to peroxide formation was shown by the crude extract and least by acidic fraction. Like PV, p-AV increased significantly in 5 months in control compared to the films containing polyphenols and same trend of results was noticed for p-AV as for PV. It is concluded that the LDPE films incorporated or coated with polyphenols are quite effective in controlling the oxidative reactions in food commodities sensitive to oxidation." xml:lang="en_US
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