Effect of post-harvest treatment on bioactive phytochemicals of Thai black rice

• Black rice should be stored as paddy in cool rooms to maintain its phytochemicals.
• Sun drying reduces loss of some black rice phytochemicals better than oven drying.
• Nylon/LLDPE under N2 is the most suitable packaging for retaining anthocyanins.
• Vacuum-packed aluminum pouches are best suited for prevention of off-flavor compounds.

Because black rice is rich in antioxidants, appropriate methods of post-harvest treatment are necessary for maintaining these bioactive phytochemicals. Drying methods, storage temperatures, storage duration, and packaging methods affected the contents of some bioactive compounds in the two varieties of Thai black rice used in this research. Sun drying reduces the loss of anthocyanins and γ-oryzanols more than does hot air drying. Glutinous black rice stored as paddy at cool room temperature retains more anthocyanins, γ-oryzanols, and vitamin E than does paddy stored at room temperature. Nylon/LLDPE pouches containing N2 are the most suitable packaging for preserving the key aroma compound 2-acetyl-1-pyrroline (2AP), total phenolic, and anthocyanin contents of unpolished aromatic black rice. These pouches also retard the formation of some common off-flavor compounds.