Pressurized fluid extraction of anthocyanins from cranberry pomace and its use in bioactive food coatings for almonds

• Author / Creator

  Rodriguez Martinez, Eduardo N

• About 94% of total cranberry production is mainly used by the juice industry, generating cranberry pomace, which is a rich source of anthocyanins. Pressurized fluids have been used to extract phytochemicals from different by-products. Such phytochemicals can be used in edible food coatings to prevent food deterioration reactions hence consumer rejection. The main objective of this study was to extract anthocyanins and total phenolics from cranberry pomace with pressurized fluids and use the extracts obtained in pectin and pectin+beeswax based coatings to prevent deterioration reactions of almonds. Pressurized fluid extractions were performed in a high pressure reactor using different solvents (water, ethanol, water+30-70%ethanol and water+5%citric acid) at 120–160ºC and 50–200 bar. Pressurized ethanol extractions were also performed at 50 bar and 40-100ºC. Spectrophotometric methods were used to determine total anthocyanin content (mg cyanidin 3-glucoside equivalent), total phenolic content (mg gallic acid equivalent) and antioxidant activity (µmol trolox equivalent). Individual anthocyanins were also quantified by HPLC-UV. Then, edible coatings, pectin based and pectin+beeswax based, were developed with the addition of cranberry extracts at ratios of 1:1 and 1:3 pectin:extract (w/w) and applied to almonds using the spraying method. Coated and uncoated almonds were stored at 40ºC and 50%RH for 90 days. Incipient rancidity of the coated and uncoated almonds was analyzed using a spectrophotometric method and almond fatty acid composition was analyzed using GC. High anthocyanin content was extracted using pressurized ethanol at 50 bar and 60-120ºC with an extraction range of 3.89-4.21 mgCy3GE/g d.w. with no significant difference between those conditions. High concentrations of cyanidin 3-arabinoside and peonidin 3-galactoside were obtained after all extractions. High total phenolic contents were obtained using pressurized ethanol30%+water at 140ºC (42.48±7.82 mg GAE/g d.w.) and 160ºC (41.19±2.07 mg GAE/g d.w.). The use of pressurized ethanol resulted in better Pearson correlation value (P=0.84) between total anthocyanins and antioxidant capacity compared to pressurized water (P=-0.35). This last value suggests possible deterioration of anthocyanins into other phenolic compounds like phologlucinaldehyde and 4-hydroxybenzoic acid. The use of bioactive coatings on almonds had no significant impact in neither the fatty acid composition nor the incipient rancidity after storage at 40ºC and 50% RH for 90 days. Also, no significant difference was observed in incipient rancidity with a peroxide value range of 2.5-4.5 mEq/kg oil. This thesis has shown that pressurized fluid extraction is an environmentally friendly alternative to extract anthocyanins and total phenolics from cranberry pomace and that the selectivity of anthocyanins with ethanol is higher compared to water and ethanol+water mixtures. Such extracts could be used as natural antioxidants or natural colorants. Also, the development and application of pectin and pectin+beeswax coating with cranberry extract was achieved. These bioactive coatings could be applied to nuts, fruits and candies.

• Subjects / Keywords

  • Almonds
  • Cranberry pomace
  • Anthocyanins
  • Pressurized fluids
  • Bioactive coatings

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R33R0Q73N

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.