Gradual cooling of kiwi fruit increases the marketable life, but also increases the incidence of decay

Temperature management is critical in maintaining quality and extending market life of ?Hayward? kiwifruit in the supply chain. In industry, harvested kiwifruit are pre-cooled using the forced draft cooling method to remove field heat. Removal of field heat reduces the rate of deterioration as fruit metabolism and growth of spoilage microorganisms are both lowered. Usually, cooling rapidly is recommended to extend fruit storability and quality. This study investigates the change in kiwifruit firmness during storage as influenced by cooling profile to the storage temperature. Commercially produced ?Hayward? kiwifruit (Actinidia deliciosa) were either cooled in 3 days or 2 weeks to the storage temperature of 0?C and subsequently stored for up to 25 weeks. Fruit firmness and respiration rate measurement was conducted every 2 to 3 weeks across the storage period. Fruit that were cooled in 3 d had higher proportion of unmarketable fruit after 100 d of storage in comparison to fruit that were cooled in 2 weeks. After 100 d of storage, fruit cooled in 3 d displayed a more rapid average softening rate. An increase in respiration rate was observed in rapidly cooled fruit after 100 d, possibly due to the stress caused by chilling injury. Higher incidence of rotten fruit was found in fruit that were cooled in 2 weeks. This study suggests that gradual cooling allows kiwifruit to acclimatize to future low temperature storage conditions, implying that rapid cooling to storage temperature may not improve the marketable life. On the other hand, gradual cooling increases the risk of rot development, where the spoilage microorganism may have built resistance against low temperature or alternatively advanced development during the initial slow cooling phase. Controlled gradual cooling of fruit is impractical with the large harvest volumes of industry. Hence there is a need to find an optimal cooling rate which removes field heat as applicable to industry. ? Complete list of authors, original title and sourcesEffect of cooling rates on kiwifruit firmness and rot incidence in subsequent storageJ.M. Zhao1, J.E. Bronlund2, A.R. East1(*)1Centre for Postharvest and Refrigeration Research, Massey University, Palmerston North, New Zealand2School of Engineering and Advanced Technology, Massey University, Palmerston North, New Zealand(*) A.R.East@massey.ac.nz V Postharvest Unlimited, ISHS International Conference, 10-13 June 2014, Cyprus The picture is by es.dreamstime.com ? ? Key wordsPoscosecha?? ?postcosecha?? ?postharvest?? ?na-oes?? ??? ??? ???????? ????? ??? ?post-r?colte?? ????? ?? ??????????? ??? ?na-oogst?? ?post-raccolta?? ?Obr?bka po?? ?p?s-colheita?? ????????????????? ?hasat sonras??? ??? ?Ernte?? ????????????????? ????? ????????????? ?postcollita?? ?poskliz?ov頠 ????? ??? ??? ??? ?nakon branja?? ?pozberov頠 ??? ?obdelovanje zemlje po?? ?post-colleita?? ?????? ??????? ?pascapanen?? ??il?onn postharvest?? ??????? ?p?c ra?as?? ?derliaus apdirbimas po?? ?lepas tuai?? ??? ?? ???????? ?post-recoltare?? ??????? ??????? ???????????????????? ?????????????? ?????????????????? ?sau thu ho?ch?? ?????????????????? ?zangemva kwenkathi yokuvunaKiwi?? ??? ??? ??? ??????? ?????? ?kivo?? ??? ???????????? ??????? ??? ??? ??? ??? ??????? ?kivi?? ??????? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ???? ?