Abstract: [Objective] The seed quality of Torreya grandis ‘Merrillii’ with different harvest maturity and retting methods was investigated to preliminarily study the variation of the seed quality during after-ripening period in response to the harvest maturity and retting methods.[Method] We measured oil content, fatty acid compositions, soluble protein content, soluble sugars content, starch content, and the distance between seed kernel and coat of T. grandis ‘Merrillii’ seeds with different harvest maturity (nearly-matured seeds, matured seeds) and retting methods (one-time retting, twice retting).[Result] Compared with the nearly-matured seeds, the matured seeds had obviously lower content of soluble sugar and starch, and their soluble protein and oil content increased obviously, especially the oil content increased by 5.6%. The changes in oleic acid and Eicosatrienoic acid were not significant, linoleic acid content, the ratio of unsaturated/saturated fatty acids and the distance between seed kernel and coat all significantly increased (P<0.05). The effect of different retting methods on the quality of T. grandis ‘Merrillii’ was significant. During retting period, the content of soluble sugars and starch in the twice retting seeds showed a decreasing trend, while the content of oil and soluble protein were increasing. When one-time retting (14 d) and twice retting (21 d) finished, the content of starch in the seeds was 8.87 mg·g^-1 and 9.03 mg·g^-1, respectively. The content of soluble protein was 23.05 mg·g^-1 and 22.79 mg·g^-1, respectively. The content of soluble sugars was 18.25 mg·g^-1 and 17.85 mg·g^-1, respectively. The oil content was 55.16% and 54.90%, respectively. There was no significant difference (P>0.05) between the two retting methods. During after-ripening period, the saturated fatty acid decreased, unsaturated fatty acid content increased. The content of oleic acid decreased with the prolongation of ripening time, and the content of linoleic acid increased obviously. There was no significant effect of the different retting methods on the ratio of unsaturated/saturated fatty acid content at the end of after-ripening (P>0.05). The distance between seed kernel and coat all increased, and the growth rate was faster with one-time retting, reaching a peak of 477 μm at 14 days (after-ripening finished), 7 days earlier to finish after-ripening deastringency compared with twice retting.[Conclusion] Harvest at matured seeds of T. grandis ‘Merrillii’ can significantly improve the soluble protein content and oil content of the kernel, increase the content of unsaturated fatty acids, especially linoleic acid, help stripping off kernel coat during T. grandis ‘Merrillii’ frying process, and then improve quality of T. grandis ‘Merrillii’ products. Using one-time retting to replace traditional twice retting can accelerate the process of T. grandis ‘Merrillii’ after-ripening, also can achieve the same effect as traditional method to ensure good quality of T. grandis ‘Merrillii’ products.

Key words: Torreya grandis ‘Merrillii’, harvest maturity, after-ripening way, quality, fatty acid compositions