Lipid oxidation stability of ultra‐high‐temperature short‐time sterilization sporoderm‐broken pine pollen (UHT‐PP) and 60Co‐irradiation sterilization sporoderm‐broken pine pollen (60Co‐PP)

BACKGROUND: Pine pollen, a kind of Chinese traditional medicine, is rich in unsaturated fatty acids. During its processing, it is often needed to break the sporoderm in order to increase the availability of some ingredients, which can cause lipid oxidation and the development of rancidity during storage. RESULTS: The primal peroxide value (PV) of ultra‐high‐temperature short‐time sterilization sporoderm‐broken pine pollen (UHT‐PP) was much higher (over 15 times) than raw pine pollen (R‐PP) and ⁶⁰Co‐irradiation sterilization sporoderm‐broken pine pollen (⁶⁰Co‐PP). The PV of UHT‐PP first increased and then decreased shortly after; however, PV of R‐PP and ⁶⁰Co‐PP remained almost unchanged during storage. The volatiles associated with rancidity in UHT‐PP were found to be significantly higher than ⁶⁰Co‐PP, especially hexanal (nearly 30 times) and hexanoic acid (about 2 times), and a multi‐organoleptic sensor analyzer (electronic nose system) was able to differentiate these three kinds of samples when the output was subjected to discriminant function analysis. During storage (30 days), hexanal first increased and then decreased (at about 5 days), and hexanoic acid continuously increased for UHT‐PP; however, no significant change was noted for R‐PP or ⁶⁰Co‐PP. UHT‐PP has a greater surface area than ⁶⁰Co‐PP, although same sporoderm‐broken processes were applied. Antioxidants (flavone, carotenoid and tocopherols, sterol compounds) in ⁶⁰Co‐PP were significantly (P ≤ 0.05, by Duncan's multiple range test) higher than that in UHT‐PP, although not significantly different for total phenolics. CONCLUSIONS: Rancidity occurs more readily in UHT‐PP than in R‐PP and ⁶⁰Co‐PP during storage, probably because significant lipid oxidation and antioxidant degradation occurred during the UHT sterilization sporoderm‐broken processing of pine pollen. © 2018 Society of Chemical Industry