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The brown alga Sargassum fusiforme (SF) is historically consumed as a food material in Japan. A steaming process is often required for SF products on the market due to their moderate hardness and astringent taste. This investigation aimed to elucidate the effect of steaming on the anti-diabetic activity of SF and its related chemical components. Acetone extracts of SF were prepared after it were steamed for 0, 1, 2, or 4 h (SF-0h, SF-1h, SF-3h, and SF-4h, respectively). Alpha-glucosidase inhibitory profiles of each SF extract were made based on activity-guided separation. The active fractions were collected and NMR was applied for a further chemical composition analysis. Our results suggested that total polyphenol levels decreased drastically after steaming, which resulted in a drop in α-glucosidase inhibitory activity. The fatty acid, pheophytin a, and pyropheophytin a contents were elevated significantly after steaming, which contributed to the majority of the activity of steamed SF (SF-1h). However, prolonging the steaming time did not significantly affect the activity of SF further since the content of free fatty acids in steamed SF (SF-2h and SF-4h) almost did not change with a longer time of steaming. Moreover, palmitic acid, 8-octadecenoic acid, and tetradecanoic acid were identified as the top three important fatty acids for the inhibition of α-glucosidase by steamed SF. Further molecular docking results revealed that these fatty acids could interact with residues of α-glucosidase via hydrogen bonds, salt bridges, and hydrophobic interactions. In conclusion, steaming altered the α-glucosidase inhibitory properties of SF by changing the contents of polyphenols, fatty acids, and chlorophyll derivatives.

The effect of storage conditions (light, temperature, container types) and time on the quality of natural olive oils from different cultivars and Australian regions were studied. The oils’ changing quality was monitored through several physico-chemical methods (free fatty acids, peroxide value, UV-spectrometry (K₂₃₂, K ₂₇₀ and ΔK), induction time, total polyphenol content, bitterness, pyropheophytin a and 1,2-diacyl-glycerol content) and sensory analysis over 24 months. Pyropheophytins a and 1,2-diacyl-glycerols criteria showed very good performance as indicators of overall olive oil quality and freshness as well as highlighting any problems during the storage of the product. Pyropheophytin a increment averaged 7 % per year and the 1,2-diacyl-glycerols decreased at an average of 23 % per year at normal storage conditions over time.

Mild refined olive oil obtained by neutralization and/or by soft deodorization at a low temperature and its blending with extra virgin olive oil (EVOO) is not allowed and is difficult to detect. Chlorophyll derivatives, pheophytins and pyropheophytin, and their relative proportions were proposed as parameters to detect such processes. The objective of this study is to determine changes in EVOO, in terms of pheophytins and pyropheophytin, occurring after several well-controlled mild refining processes. The changes on those chlorophyll pigments due to the processes depend on the temperature, stripping gas, acidity and oil nature. The data obtained show that, at temperatures below 100 °C, the rate at which pyropheophytin a is formed (Ra) is lower than the rate at which pheophytins a+a’ disappear (Ra+a’). As a consequence, the Ra+a’ and Ra ratios are considered to be directly linked to pheophytins a+a’ decrease instead of to pyropheophytin a formation. Stripping gas very slightly affects the transformation of the chlorophyll pigments; actually both acidity and N2 enhance the increment in the Ra+a’ and Ra ratios. In relation to the oil nature, the higher the initial pheophytin a+a’ content, the higher the increase in the Ra+a’ and Ra relations.

In previous studies we reported the presence of compounds with spectral characteristics similar to pheophytin α (Pheo α), which often accompany the Pheo α peak in the chromatographic profile of virgin olive oils (VOO) at 410 nm under normal‐phase HPLC conditions. The occurrence and levels of these compounds were found to be affected by storage conditions of the oil samples. In the present study we investigated whether the major Pheo a degradation products, identified as pyropheophytin α (coeluting with the respective epimer) and 132‐OH‐pheophytin α, could be used as estimates of VOO history. The content of Pheo α and its degradation products was determined for a great number of authentic olive oil samples of unknown history. Results are discussed in comparison with other quality indices (e.g., antioxidant content) when necessary. High amounts of the pyro form (20–30% of total pheophytins) were related to thermal abuse or lengthy storage. The presence of allomers indicated oxygen availability. The levels of these products, 0–20% of the total pheophytin content for 62% of the samples, seemed to be influenced by the presence of pro‐ and antioxidants. When low levels of Pheo α are not accompanied by other degradation products, light exposure for a certain period of storage can be assumed.