Determination of optimal maturity indices for South African golden kiwifruit cultivars

N. Mahlaba, S.Z. Tesfay, M. Dodd, L.S. Magwaza, A. Mditshwa, N.Z. Ngobese
Kiwifruit (Actinidia chinensis) exhibits little to no visible evidence of physical quality attributes considered as perfect indicators of fruit developmental stage of which maturity can be measured. Maturity indexing is a perfect tool that is used in determining the optimum picking time and its effect on kiwifruit quality during postharvest storage life. Therefore, this study was conducted to develop a protocol on maturity indexing for the selected golden kiwifruits grown under South African conditions. Two golden kiwifruit cultivars ('Y368' and 'Soreli') were harvested from Richmond (KwaZulu Natal, South Africa). An early harvest was conducted, and samples were collected weekly for 10 consecutive weeks (H1-H10), until the anticipated harvest date. Fruits were stored at 0°C for 2 months and after storage, fruits were left for 7 days for shelf-life study. The experimental design used in the study was a randomized complete design (RCD). Fruits were sampled at harvest, after cold storage, and end of shelf life for soluble solids content (SSC), dry matter (DM), and firmness parameters. The results showed that the harvesting time had a significant effect (P<0.001) on all maturity quality parameters: SSC, DM, and firmness. SSC and dry matter had a linear increase while firmness decreased with increasing in harvest time. 6.2 °Brix SSC has been long used in the kiwifruit industry as a minimum value for harvesting. First harvested fruit recorded SSC at 4-5 °Brix, SSC accumulation in response to harvest time showed a slow to the more rapid increase and the last harvest had a SCC of 6-7 °Brix for both cultivars where they had a better postharvest performance. A pattern of softening was observed, and late harvested fruits were softer but retained firmness better than early harvested fruit during storage. The findings can conclude that harvesting time influences SSC, DM, and firmness.
Mahlaba, N., Tesfay, S.Z., Dodd, M., Magwaza, L.S., Mditshwa, A. and Ngobese, N.Z. (2022). Determination of optimal maturity indices for South African golden kiwifruit cultivars. Acta Hortic. 1332, 335-342
DOI: 10.17660/ActaHortic.2022.1332.44
kiwifruits, maturity index, total soluble solids, dry matter, titratable acidity

Acta Horticulturae