Analysis of the effect of sterilization and storage on the quality of Pinus yunnanensis pollen based on untargeted metabonomics

Abstract

Pine pollen refers to the male reproductive cells of Pinus massoniana Lamb., Pinus tabulaeformis Carr., Pinus thunbergii Parl., and Pinus densiflora. It is rich in diverse proteins, amino acids, vitamins, minerals, dietary fiber, lipids, peptides, and flavonoids (Dai et al., 2019) and has various bioactivities (Luo et al., 2012;Mao et al., 2012). Fresh pine pollen is difficult to store because of high water content, so it is essential to be dried and sterilized. Sun et al. (2007) studied the influences of electrothermal drying and circulating hot air drying on black pine and red pine pollen and the result showed that the water content met the requirements of the first-grade pine pollen (6.0% and 5.2%) after drying at 45 and 55°C for 6 hr. Simultaneously, they could keep the quality, shape, and sensory characteristics of pine pollen. Li et al. (2015) optimized the parameters of pine pollen microwave drying and sterilization technology via the response surface method and found that after the optimized process, the water content of pine pollen was 4.23%, and the numbers of bacteria and mold were 2.43 × 10 4 and 23.72 CFU/g, respectively. Drying treatment could reduce the water content of pine pollen, thereby prolonging the shelf life of pollen. Li and Zhou (2017) also found that low temperature (−20°C) could extend the storability of pine pollen. Since traditional heat sterilization will cause changes in food nutrition and flavor substances to some extent, especially some heat-sensitive substances. So non-heat sterilization technology has received more attention in recent years. Common non-heat sterilization included ultrahigh pressure and irradiation sterilization. These methods are equally commonly used to sterilize pine pollen. Initial studies had

Fatty Acid Composition of Dry and Germinating Pollen of Gymnosperm and Angiosperm Plants

“…As for the less abundant FAs, in Picea pollen we found 5,9,12-18:3-one of ∆5 FAs-which has previously been found in the pollen of other gymnosperms, including Pinus yunnanensis [38], other Pinus species [35] and Cycas revoluta [6]; moreover, in the first case, its content decreased during storage and sterilization in parallel with the loss of pollen quality [38]. Gymnosperm seed lipids are also characterized by the presence of peculiar FAs containing ∆5-ethylenic bond, frequently referred to as ∆5-olefinic acids, with 18 or 20 carbon atoms, which are seldom encountered in angiosperms [39].…”