Jujube extract was concentrated by various heating methods including vacuum, microwave and conventional heating. The effect of concentration methods and storage time (for 90 days at 4 °C) on total phenolic and total monomeric anthocyanin contents, individual anthocyanins, individual organic acids, and color values of jujube concentrate was investigated separately. The desired level of concentration (65.0 °Brix) was achieved in 45, 96 and 117 min by the microwave, vacuum and conventional heating methods, respectively. The concentrate obtained with microwave method had the highest total phenolic content (159.32 mg GAE/g DW) and total monomeric anthocyanin content (48.84 mg cyn-3-glu/100 g DW) in comparison to the other methods at the beginning of storage. Hunter color parameters (, and) decreased significantly with increasing the time of storage in all cases; however, this effect was more obvious in the vacuum heating. Cyanidin-3,5-diglucoside was determined as the major anthocyanin in all concentrates, while its degradation was more pronounced in the conventional heating (25.59%) comparing to the microwave (11.14%) and vacuum methods (17.59%) during the 90-day storage. The jujube concentrate prepared with the microwave method had the highest organic acid contents (e.g. malic, citric, succinic and ascorbic acids) as compared to the other methods. Thus, according to the results, the heating method and storage time had significant effects on the bioactive compounds and color values of jujube concentrate. In general, microwave energy could be successfully used in production of jujube concentrate followed by 90-day storage.
PurposeCarotenoids have been extensively used in many industries owing to their colorant and strong antioxidant properties. Because of their useful properties, the purpose of this paper is to investigate the effect of penicillin‐adding time on stimulation of carotenoid production by Neurospora intermedia, and the effect of drying methods on stability of synthesized carotenoids.Design/methodology/approachIn the first stage, curve of growth kinetic of cultures incubated at 31°C and different times (24, 48, 72, 80, 96, 104, 112, 120, 128, 136 and 144 h) to determine log and stationary phases was depicted. Then penicillin (1 mg/l) at initial and middle of log phase and initial of stationary phase was applied and its effect on carotenoid production was evaluated. In the second stage, mycelia containing carotenoid were dried by microwave oven, vacuum microwave, vacuum oven and freeze drier. Thereafter, effect of drying methods applied on stability of synthesized carotenoid was determined.FindingsThe results showed that penicillin could stimulate carotenoid biosynthesis in N. intermedia. Furthermore, this study indicated that the best time of penicillin adding is middle of log phase or after this time. Also the study indicated that there was a significant difference among applied methods as microwave‐dried mycelium had the highest carotenoid contents in comparison to the other drying methods.Originality/valueThis paper is believed to be the only one which investigates the effect of different factors on stimulate and stability of synthesized carotenoid by N. intermedia. Also mycelia containing carotenoid were dried by using new drying methods.
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