Edible flowers with the common name "marigold": Their therapeutic values and processing

Background: Edible flowers are defined as innocuous and nontoxic flowers with health benefits when consumed as human diet. So far, hundreds of edible flowers have been identified. Among them, marigold is one of the popular edible flowers which has been used from ancient times. Scope and approach: There are different species of flowers with the common name "marigold". We have summarized five of them, namely common marigold (Calendula officinalis), marigold (Tagetes erecta), French marigold (Tagetes patula), Mexican mint marigold (Tagetes lucida), and lemon marigold (Tagetes tenuifolia), along with their phytochemical content, physiological effect of these components, and toxicological studies. We have also reviewed the literature dealing with the processing of marigold flowers, such as drying, extraction, and packaging, to find their effect on the bioactive components. Key findings and conclusions: The phytochemical composition of these flowers revealed them to be wonderful natural gifts containing many therapeutic values. Processing of these flowers showed that drying was the most effective method to preserve them; however, novel and hybrid drying technologies using microwave, far infrared, and ultrasound etc. are still to be studied. Last but not least, it was concluded that marigold flowers are wonderful gifts loaded with natural phytochemicals, if properly processed.