Production and postharvest handling of low acid hybrid pineapple

N.J. Chen, R.E. Paull
The development of pineapple cultivars more suited for fresh fruit consumption has led to new hybrids that have been widely introduced in Hawaii, Australia, Malaysia and Taiwan. These low acid types have become the preferred types and have expanded rapidly to supply the fresh fruit markets of the USA, Japan and Europe. The newer cultivars present new challenges for producers trying to ensure consistent production and quality. In Hawaii, plant establishment, natural flowering, translucency and too low acid levels are quality issues all tied to production practices. Production practices and experience gained over decades with the older canning types does not always readily apply to these low acid hybrids. Differences are seen between the two preferred low acid clones '73-050' and '73-114' in rooting. The clone '73-050' is slow to become established that delays crop growth upwards of a month. Natural flowering increases harvest costs and production losses, and disrupts the marketing of a consistent supply of high quality fruit. This event is a serious problem for the new low acid hybrids. The problem is more severe in regions with a cool season having temperatures below 20°C and shorter day length. Aviglycine (Retain©), an ethylene biosynthesis inhibitor, and methylcyclopropene (1-MCP), an ethylene receptor inhibitor, can control natural flowering. However, both are very costly and further studies are needed to reduce costs while maintaining efficacy. Alternatively, plants have been genetically engineered to be less sensitive to natural flowering conditions. All approaches have been tried in Hawaii. Fruit with flesh translucency increases the fruit's susceptibility to mechanical injury, fermentation and non-pathogenic fungal growth on the broken peduncle, all are of concern with packers, marketers and consumers. Translucency is possibly due to high photosynthetate levels in the fruit during the later part of fruit growth. Other possible factors include insufficient calcium uptake during early fruit growth and higher fruit temperatures in the field. Another issue is the inconsistency in fruit quality throughout the year due to variation in the sugar to acid balance, the major fruit flavor component. In the warm season, Hawaii's fruit have high sugars and too low acids. A more desirable balance of acids and sugars occurs in the cool season. The low acid hybrids accumulate high levels of titratable acidity during fruit growth. This acidity peaks at a higher level than in the older canning cultivars and declines rapidly as the fruit approach maturity and ripens. Field management, such as fertilization, irrigation practices and harvest scheduling developed for the canning cultivars may not be the most appropriate for the production of low acid hybrids' fresh fruit. This difference in varietal responses highlights the need for new field and handling approaches to meet the consumer desire for a consistent supply of high quality fruit.
Chen, N.J. and Paull, R.E. 2017. Production and postharvest handling of low acid hybrid pineapple. Acta Hort. (ISHS) 1166:25-34
Ananas comosus var. comosus, propagation, natural flowering, flowering control, fruit quality, low acid cultivars, acidity, sugar accumulation, translucency

Acta Horticulturae