Title: Microorganisms and antifungal properties associated with noni (Morinda citrifolia) fruit and fermented juice in Hawaii Authors
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2011
Publication Date: June 15, 2011
Citation: Nishijima, K.A., Wall, M.M., Keith, L.M. 2011. Microorganisms and antifungal properties associated with noni (Morinda citrifolia) fruit and fermented juice in Hawaii. Phytopathology. 101:S129. Technical Abstract: Noni (Morinda citrifolia), a medicinal plant grown in Hawaii and other Polynesian regions, is reportedly therapeutic for diabetes, high blood pressure, and certain types of cancer. Noni fruit often produce fermented juice that differs in chemical, physical and microbial properties. To determine how storage factors affect juice quality we investigated the occurrence of microorganisms during noni fermentation and also report on antifungal properties of pasteurized juice exudates in in vitro bioassays. Firm, yellow, mature noni fruit were held in sealed glass jars for up to 42 days at 22ºC. Juice exudates were analyzed weekly for microbial populations and chemical properties. Puree of fresh soft fruit was also analyzed. In vitro bioassays consisted of PDA plates spread with spore suspensions of fungal pathogens and spotted with juice, puree, or sterile distilled water. Bacterial populations did not differ from 0 days up to 35 days, but were highest at 42 days. Mucor circinelloides f. sp. circinelloides, a fungus consistently isolated among fermented juice samples, had populations that peaked at 14 days. Fresh noni puree was microbial-free or low in microbial populations. Total soluble solids (% TSS) were highest in fresh noni (9.8) then decreased after 14 days (5.7) storage. In bioassays of noni puree or juice, antifungal activity was absent at 4 to 5% TSS; intermediate at 6% TSS; and highest at 7% TSS or greater, regardless of storage duration. Our studies determined microbial and chemical profiles during storage and TSS range of noni juice with antifungal activity against several pathogens of tropical fruit crops.