Effect of maturity on carbohydrate changes in sugar snap pea pods during storage

Abstract

To determine the effect of maturity at harvest on compositional changes during storage, sugar snap peas ( Pisum sativum var. macrocarpon Ser., cultivar ‘Sugar Daddy’) were harvested when mature (the seeds filled the hull without deforming it), immature (the seeds did not fill the hull) and over-mature (the seeds deformed the hull) and stored at 0°C for a period of 3 weeks. Sucrose made up the bulk of the total sugars in the seeds and levels increased markedly during storage of immature and mature seeds, whereas the overmature seeds showed no change. During storage, glucose level increased in immature seeds, remained the same in mature seeds and decreased in overmature seeds. Fructose level also increased in immature seeds and slightly increased in mature seeds, but was not present in overmature seeds. Before storage, hulls of immature samples contained less than half the amount of sucrose found in more mature hulls. However, the total sugar content of immature hulls increased during storage, whereas that of more hulls decreased. Glucose made up a large proportion of the total sugars in hulls and showed a significant increase during storage of immature samples. Seed percent dry weight (%DW) and percent alcohol insoluble solids (%AIS) increased with maturity and also during storage. Regardless of maturity %DW and %AIS of hulls decreased with storage. This suggests that the AIS material is broken down in the hulls and the nutrients are transported to the seed where, depending on pod maturity, they are added either to the sugars of AIS.