Histological changes in pineapple fruits (Ananas comosus ‘Smooth Cayenne’) in three stages of shelf life

Growing pineapples on a commercial scale is very profitable, and the market continues to grow worldwide. Pineapple fruit has organoleptic properties that make the fruit very desirable to the consumer, however the fruit must have high quality requirements for marketing. A necessary attribute is the shape of the fruit and an increase in shelf life. The postharvest life of the fruit is related to changes in time at cellular levels, the increase in sugars, the decrease of acidity or firmness. Histological microscopy allows us to observe these changes over time and relate them. In the present work, were studied the cellular arrangements of pineapple fruits (Ananas comosus ‘Smooth Cayenne’), comparing small fruits with large fruits and in different ripening stages. Fruits obtained from farm of the State of Tabasco, Mexico; histological slides were made at different depths and heights, comparing i) fruit size: small and large, and ii) in three ripening stages: 0, all eyes totally green; 2, 20-40% of eyes in yellow and 5, 90% of eyes completely yellow, according with the color scale of Selvarajah et al. (2001). The variables determined were the number and area of vascular bundles (VB´s), number of xylems, size of phloem, sclerenchyma and parenchyma, all this in histological sections of 1×1×1 cm cubes sampled in distributed regions of fleshy and core tissue. The results obtained show that the size of the cells does not change between large and small fruits, that there is a collapse of the phloem tissue and sclerenchyma in fruits with a higher degree of maturity and size. In the epidermis, thinning of the cuticle, decrease in the size of epidermal cells, irregular sizes, degradation of cell walls and intercellular spaces were observed in pineapples with greater maturity and larger size. In the histological comparison between small and large fruits, differences were observed in the sizes and quantities of cellular elements in the different regions evaluated.