The order and combination of juicing steps can change a blueberrys bioactive phytochemicals and effect juice recovery. In addition to physical treatments such as pressing, recovery is also affected by heat and enzymes steps. Not optimizing juicing methods affect juice quality and leave many bioactive components in the press cake. To evaluate pre-press treatments, southern highbush and rabbiteye blueberries were individually pressed in a bench top press at varying temperatures. The temperature treatments included fresh, thawed, frozen and heating to 95 °C. Two pectinase enzymes, Rohapect 10L and Pectinex BEXXL, were individually used to assess impact on juice extraction. Juice recovery was averaged from three press replications for each treatment. Frozen berries which were heated to 95 °C and treated with enzyme had the highest recovery at 68.6 ± 1.1%. This process was then transferred to a pilot scale press. Pilot scale juice recovery was calculated at 74.0 ± 0.9%. Using data from the initial pilot presses, a full pilot scale experiment was triplicated. Tifblue rabbiteye blueberries were heated in a steam jacketed kettle to 95 °C for three minutes followed by a Rohapect 10L enzyme treatment before pressing. The resulting juice from the pilot press was then filtered and pasteurized. Unfiltered juice was also pasteurized. Press cake was collected and frozen. Samples of raw berries, filtered and unfiltered juice, pasteurized juice, and press cake were taken to identify anthocyanin compounds and changes caused by juice processes using LC-MS/MS. Samples were also hydrolyzed for anthocyanidin quantification using UPLC-UV. Ten major anthocyanins were identified, including 5 arabinoside and 5 pyranoside anthocyanins and three minor anthocyanins. The five anthocyanidins, cyanidin, delphinidin, malvidin, peonidin, and petunidin, were quantified. Raw berries and press cake contained the highest anthocyanidin contents with 85.1 mg/100 g and 265.6 mg/100 g respectively. Decreases of 67% loss after pressing and 10% loss after pasteurization were determined for anthocyanins and anthocyanidins in juices. However, three new conjugated anthocyanins were found in processed juices which have not previously been reported in rabbiteye. This contributes to the value and interest of press cake for use in other food and non-food products.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-11162015-005043 |
| Date | 14 December 2015 |
| Creators | Stein-Chisholm, Rebecca Elaine |
| Contributors | Losso, Jack N., Finley, John W., Beaulieu, John C. |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-11162015-005043/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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