EFFECT OF ONION (Allium cepa Linn.) SKIN EXTRACT ON OXIDATIVE STABILITY OF GHEE

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dc.contributor.advisorSharma, R. S.
dc.contributor.authorJain, Aditya K.
dc.date.accessioned2018-06-29T10:16:51Z
dc.date.available2018-06-29T10:16:51Z
dc.date.issued1996
dc.description.abstractA study was carried out to elucidate the effect of addition of antioxidant principles of onion skin via a preextract on the oxidative stability of ghee. A composite sample of onion skin obtained from local vegetable market contained 9.56 per cent moisture, 0.79 per cent fat, 0.56 per cent protein, 8.35 per cent ash and 80.74 per cent carbohydrates as major constituents. It also contained 3.17 per cent total phenolics, 0.41 per cent water extractable phenolics and 0.015 per cent phospholipids. Fresh ghee manufactured in a commercial dairy by creamery butter method employing prestratification and clarified at 110°C without' any holding period was used for the study. The antioxygenic compounds of onion skin were extracted into methanol, dried and ground to get a fine powder which was added to ghee at a rate of 0.5 per cent (w/v). The mixture was kept at 40 ± 2°C for 12 h and then at 50 ± 2°C for about 3 h followed by decantation of clear ghee, the pre-extract. This pre-extract was finally added to ghee at the rate of 0 (T0, control), 10 (T1), 15 (T2) and 20 (T3) per cent levels constituting different treatments. For comparison, the last treatment was addition of butylated hydroxy anisole (BHA) at the legally permitted rate of 0.02 per cent (T4) . To monitor the effectiveness of the additions, peroxide value of all ghee samples was determined immediately after receiving the ghee and after every 48 h interval of storage at 80 + 2°C in a memmert type oven. The pre-extract contained on an average 21.3 mg per cent water extractable phenolic compounds. The water extractable phenolics content of ghee samples added with the pre-extract at various levels were in order : 3.580 mg/100 g (T3) > 2.894 mg/100 g (T2) > 2.211 mg/100 g (T1) > 1.106 mg/100 g (T4) > 0.843 mg/100 g (T0). The antioxygenic indexes were in the order : 1.22 (T4) > 1.19 (T3) > 1.17 (T2 and T1) > 1.00 (T0). From the results of this study, it is concluded that the antioxygenic compounds of onion skin can be extracted in a crude form using methanol, dried and ground to obtain a fine powder. Addition of these antioxygenic compounds in the form of pre-extract enhanced the oxidative stability of ghee. Addition of such pre-extract at all the levels studied in this experiment (10, 15 and 20 per cent, v/v) was found to be almost at par with addition of BHA at 0.02 per cent level. The phenolics present in the onion skin appear to be the main contributory factors in enhancing the oxidative stability of ghee. Quercetin and anthocyanin, the phenolic compounds reported to be concentrated in the onion skin are expected to be the principal antioxidants. Besides these compounds, carotene, Vitamin C and phospholipids/ phosphorus containing compounds of onion skin could also be responsible for part of the antioxidant effect observed.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/5810055867
dc.keywordsEFFECT OF ONION (Allium cepa Linn.), SKIN EXTRACT ON OXIDATIVE, STABILITY OF GHEEen_US
dc.language.isoenen_US
dc.publisherAAU, Ananden_US
dc.research.problemEFFECT OF ONION (Allium cepa Linn.) SKIN EXTRACT ON OXIDATIVE STABILITY OF GHEEen_US
dc.subDairy Chemistryen_US
dc.subjectDAIRY CHEMISTRY, DAIRYINGen_US
dc.subjectA STUDYen_US
dc.themeEFFECT OF ONION (Allium cepa Linn.) SKIN EXTRACT ON OXIDATIVE STABILITY OF GHEEen_US
dc.these.typeM.Scen_US
dc.titleEFFECT OF ONION (Allium cepa Linn.) SKIN EXTRACT ON OXIDATIVE STABILITY OF GHEEen_US
dc.typeThesisen_US
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