A Review of Pistachio Kernel Composition during Fruit Ripening

Pistachios (one of 50 healthy foods) are essential for human health. The ripening stage is of great importance for food processing, as the chemical composition of this fruit is heavily influenced by its maturity level. For instance, as premature pistachio has unique green color, it can be used in desserts, sauces, ice creams, and chocolates, while mature pistachios often used as snacks. Considering that the nutrients in the pistachio kernel are dependent on various factors, especially environmental conditions, determining the amount of these compounds during the ripening stages of the pistachio kernel can considerably contribute to the appropriate harvest time and increase the duration of its storage period. Biochemical compounds such as carbohydrates, fats, and proteins are less affected by growth but may affect pistachio kernel taste and its nutritional value and health. The highest amounts of carbohydrates, fats, and proteins are available at the time of optimal harvesting when the hull is fully ripe. Phenolic compounds and antioxidant activity of pistachio decrease during ripening, and oil and fatty acid levels increase with the ripening period. In the case of the color parameter, the L factor decreases during the ripening period, and the a and b factors increase. Different stages of ripening have a significant effect on pistachio compounds. Nutrients in pistachio kernel are dependent on various factors that their diagnosis in different stages of growth contributes considerably to harvesting at the right time and increasing the storage period of this product.