We investigated the influence of both the clarification by ultrafiltration membranes with 100 or 18 kDa molar weight cut-off (MWCO) and subsequent storage on phenolic properties and color of mulberry juice (MJ). Results showed that clarification by the ultrafiltration membrane with 100 kDa MWCO elevated levels of total polyphenols (↑11.4%), total monomeric anthocyanins (↑87.7%), phenolic acids and flavonoids (↑10-64%), thus leading to enhanced antioxidant activity (↑twofolds) and α-glucosidase inhibitory rate (↑23.3%), as well as redness (↑37.9%), which were sharply decreased in the clarified MJ by the ultrafiltration membrane with 18 kDa MWCO. MJ pretreated by the membrane with 100 kDa MWCO exhibited better storage stability than the other two juices. Hence, the ultrafiltration membrane with 100 kDa MWCO has great potential in juice clarification for purpose of enrichment of phenolic compounds, and enhancement of bioactive activities and storage stability. PRACTICAL APPLICATION: Mulberry juice has many health benefits related to phenolic compounds. Clarification is necessary to obtain a bright, clear juice and improves juice taste, thus making a favorable first impression on consumer. Ultrafiltration membrane with 100 kDa MWCO is recommended in mulberry juice processing, since it helps to enrich phenolic compounds, and enhance bioactive activities and sensory quality of mulberry juice.
Keywords: bioactive activities; mulberry juice; phenolic compounds; storage; ultrafiltration membrane.
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