Thanks to literature and fellow scientists

Abstract

Formal training has the disadvantage that trainees may simply accept what they are taught without questioning it, unlike the autodidact who can only learn by asking questions all the time. Sometimes, he will not get an answer and that need not be because the question is stupid, but may be because his peers are used to there being no satisfactory answer and have simply accepted the conventional mythology without further question. So it is about time to ask some assorted questions and where possible, suggest how to find an answer: 1) Why does the composition of the solvent used to extract oil from oilseeds affect the amount of oil being extracted and its phosphatide content? 2) Why does a heat treatment (Alcon, Exergy, expander) increase the phosphatide content of the crude oil and decrease its non-hydratable phosphatide (NHP) content? 3) Why does water degumming of crude oil remove relatively more magnesium than calcium? 4) What is the mechanism of phosphatide removal by silica hydrogel and why is it enhanced by simultaneous soap removal? 5) What is the mechanism of NHP-removal during alkali neutralisation? 6) Could it be that the Long Mix neutralisation process as used in the US leads to insufficient removal of the pro-oxidants copper and iron and that this explains why oil tends to less stable in the US than in Europe, especially when it contains linolenic acid? 7) Could different deodorisation conditions explain this geographically determined anomaly? 8) What happens during flavour reversion? 9) Why is walnut oil more stable in the nut than in the bottle? 10) How much oil is lost by saponification or hydrolysis during refining? 11) What is the mechanism of colour fixation? 12) Does the activity of interesterification catalysts depend on their counter cation? 13) What is the chemical nature of the colour formed on interesterification catalyst activation? 14) What is crystal memory? Does it exist? However, we should not forget the Dutch proverb that: "One fool can ask more questions than ten wise men can answer." On the other hand, exposing myths is half the fun and asking the right question often provides half the answer.

Response to the Letter to the Editor Regarding “A Novel Evaluation Index for Predicting the Degradation Rate of Frying Oils Based on their Fatty Acid Composition”

“…He also found that monounsaturated fatty acids were almost insusceptible to oxidation, while linoleic acid and linolenic acid were extremely susceptible. His research was all carried out at 120 °C with an automatic Rancimat apparatus, which was close to theoretical autoxidation experimental conditions. Different from his research, our research was conducted under real frying conditions at 180 °C, which was very close to the actual frying process in life.…”

“…By carefully reading the introduction and the original text of the previously published article mentioned in the Letter, we knew that Dr. Albert Dijkstra had done a lot of research on the oil stability index (OSI). He found that the OSI of oil blends can be expressed as the sum of the antioxidant contents of the blend components divided by the sum of the weighted susceptibilities to the oxidation of the fatty acids in the blend.…”

Questions begging for answers (Part IV): Oil stability

“…Hence, the continuous efforts to discover why oils are so unstable, how different oils compare and what to do about it. So, when I was still in charge of an R&D laboratory we also studied oil stability and we even published the results . We used the Rancimat apparatus to determine the Oil Stability Index (OSI) and by testing a large number of binary blends of twenty vegetable oils and fats, we concluded that this index can be predicted on the basis of the antioxidant content of the oils and constituting the blend and the fatty acid composition of the blend according to: …”

Simplicity is a Worthwhile Goal but Does Not Always Provide the Correct Answer

“…It is therefore with great interest that I studied the article by Liu et al because it claims to provide a novel evaluation index for frying oils that only takes their fatty acid composition into account. Another reason that I studied the article with great interest is that some 20‐odd years ago, I wrote a paper that also correlates the stability of an oil to its fatty acid composition. The difference between the work by Liu et al.…”

“…Because the paper I wrote is not that readily accessible since it dates from before 2000—the year in which Oléagineux, Corps gras, Lipides, the French oils and fats journal (OCL)‐back issues became freely accessible via the Internet—I will briefly summarise its findings. These include that the Oil Stability Index (OSI) of oil blends can be expressed as the sum of the antioxidant contents of the blend components divided by the sum of the weighted susceptibilities to oxidation of the fatty acids in the blend.…”