Glad you liked it! Thank you.

Thank you for engaging with my content. To answer you, what will catalase and GO be doing in the stomach? that is a different environment than what they are used to. Hypothetically speaking, the high acidic pH would render those enzymes inactive by altering the native confirmation.

Good day Alex, Thank you for engaging with my content. In terms of your question, I usually use the Farmer's hydroperoxide mechanism to explain how antioxidant function to inhibit/prevent oxidation. Lets start at initiation - metal initiators that abstract the hydrogen can be chelated using antioxidants such as EDTA, prolonging the induction period. In the propagation stage, oxygen scavengers can react with oxygen . Free radical scavengers can donate hydrogen to alkyl, peroxyl or alkoxy radicals, to prevent them from stealing another Hydrogen from a new fatty acids

Thank you for engaging with my content. Regarding your question, the oxygen appears in the second step of the induction stage. Therefore in this case, without it oxidation will not proceed under the conditions of vacuum and maybe Modified and Controlled Atmospheric Packaging that you alluded to. But lets not forget in cases where the enzyme lipoxidase (lipoxygenase) is present and active in the product, it catalyses the reaction of an unsaturated fatty acid to directly form lipidhydroperoxides without the aid of oxygen. The formed peroxides will then further break down to continue the reaction provided the are initiators such as metals or higher temperature. So to answer your question directly, yes lipids can become rancid without the oxygen only if the enzyme lipoxidase is present.

Thank you for engaging with my content and for the question. In my own experience, I have come across a vegetable oil (sunflower) that oxidised, and produced an off flavour. However, this oil I had extracted (crude) myself ,and left at room temperature for 3 - 5 years. This experiment was for educational purpose for my students. The oil became rancid and started forming gums around the opening of the bottle (PET). I have never experienced any rancidity of animal fat, in the period of normal use. It would be interesting to get hold of the literature or research the Professor was using, it might be that that is another lipid phenomenon. But I surely stand by the notion of saturated fats are less prone to oxidation than their unsaturated counterparts'. In terms of your observations, just note that commercially sorls sunflower oil is refined first, and then added with the antioxidant TBHQ. Moreover, you probably had it stored under proper conditions. Fish on the other hand oxidises much quicker. Butter undergoes hydrolysis easily than oxidation, and whatever off-flavours you perceived were related to hydrolytic rancidity. There is another type of oxidation "photooxidation" that is seldom talked about, and it affects a lot of dairy products during display in retail shops. In the case of products that contain other food components other than just lipids, they would also accelerate oxidation due to presence of these other components. Lipid degradation is such a complex phenomenon. I hope I shed some light, but i have different experience and opinion from the Professor

You are welcome

Thank you for engaging with my content. I would like to believe that the content in the video " Chemical changes of fats and oils during frying" does describe the process of thermal degradation of lipids, focusing on points such as, elevated temperatures, presence of oxygen, fatty acid type. Thermal degradation of lipids is somewhat similar to normal oxidation but with its rate accelerated. For instance, at room temperature, oxidation might results in rancidity only, but thermal decomposition might results in rancidity, colour darkening and resin (gummy) like texture due to polymerisation. All that was covered in the video. I hope I answered your question.

Thank you for taking your time to watch my videos, and giving feedback. Just a few questions: what type of oils did you work with? Were your storage conditions real time or accelerated? Reason being at high temperatures oils oxidise faster and form aldehydes and ketones which are then measured using P-anisidine value. However, continued storage under those conditions may lead to the next step of polymerisation of oxidation products (aldehydes and ketones) leading to increased viscosity (gummy/sticky). It might happen that the newly formed polymers do not represent the structure of an aldehyde or ketone, thus not being absorbed at 350 nm. Remember polymerisation is also a process, therefore, AV can reduce before the visual effects are perceived.

I'm glad the video was of help. Thanks.

Hello Real Christopher. I am glad you found the content of this video simple to understand. Thank you for the positive comment, it gave me a boost to do more🤗.

​@@lusanivhangani2768 Ah ha! Makes sense now! I connected the dots! You are a scientist of Cape Peninsula University of Technology! Not some "tuition teacher" online. Many of those "teachers" complicate what is already complicated. Some of them oversimplify things to the extent that data becomes inaccurate or outright wrong. Simplify things but not any simpler.

Thank you.

I'm glad it was helpful. Thanks for watching.

Hi There. Some authors have reported on the prooxidant effect of salt of meat and meat products, where salt was responsible for liberating iron from ions from Iron-containing molecules. Iron is known as an accelerator of the Lipid Oxidation induction period. In potatoes and nuts the salt can play a similar role if Fe and Cu are present, thus have the same effect. I haven't come across such in literature, I'm speculating. For more reading check: dx.doi.org/10.1016/j.foodres.2017.02.003

@@lusanivhangani2768 hii, thankyou for the explanation.

Hi There. I'm assuming when you say "simple chemical composition" you referring to if the fatty acids were all saturated and maybe short chains. The same chemical reaction (lipid oxidation) will take place, the difference will be the onset of the reaction will be delayed for saturated fatty acids since it is takes more energy to abstract that hydrogen form saturated carbons. in some cases extreme conditions such as frying the oil/fat at high temperature repeatedly will accelerate the reaction. I hope this makes sense

@@lusanivhangani2768 Thanks you very much❤️

Oh wait, i meant to say simple chemical change not chemical compositin

@@yallugly363 I'm glad i could be of help to you.

@@yallugly363 Remember the extent of the chemical change depends on the extent on the factors, for instance the more the double bonds, the higher the temperature, the more the initiators such as sunlight and metals, the heightened the oxidation. Same applies when the fat/oil is stored at lower temperatures away rom direct sunlight, the lesser the change.

Thank you

Thank you. I'm glad my content could be of help to you. All the best with your class.

Thank you

Hello there. The darkening is due to the "Maillard Reaction" due to sugar protein condensation.

You are welcome. Thank you for viewing

You are welcome

Thank you

@@lusanivhangani2768 Could you recommend something like Ascorbic Acid for balancing Banana Leaves?

@@shashikaalahakoon3287 I'm not sure what you mean by balancing banana leaves. can you explain this concept.

​@@lusanivhangani2768 I need to freeze banana leaves for future use. So I thought of putting them in boiled water mix with Ascorbic acid. After 1 minute, I'll put them on Ice water before freezing. Do you think will it work?

@@shashikaalahakoon3287 I have no knowledge of freezing banana leaves, sorry I cannot help in this regard.

Thank you too. I will keep "the stupid examples"

Thank you for the feedback

Good day. Apologies for a late reply. Notification for this comment passed me. Yes, lipid oxidation will take place in any lipid (fatty acid) whether esterified or free. The acid value measures the fatty acids that broke/separated from the ester bond to form what we call (free fatty acids), the main reaction is on the ester bond, on the other hand, peroxide value is based on oxidation that took place on the actual hydrocarbon where ROOH was formed on the chain. These two are in directly related, since if a free fatty acid is formed, it's affinity is on the interface of the oil and air, thereby resulting in reduced surface tension, allowing oxygen to enter the oil and then cause oxidation, which will form ROOH (peroxides). The only mathematical relation I can say (based on my opinion) will be calculating the rate of peroxide formation between a pure lipid vs a lipid that has been hydrolysed to form free fatty acid.

Good day. Thank you for the compliment. I obtained this information form a review article by Choe, E. & Min, B.D. (2006). Mechanisms and factors for edible oil oxidation. Comprehensive Reviews in Food Science and Food Safety, 5, 169-186. I hope this information helps.

Thank you for the compliment.