Preparation of juice concentrates by nonthermal processing technologies: a multiple hurdle approach

The conventional preparation of juice concentrates is by thermal evaporation. However, some quality attributes, nutrients, bioactive components, and other volatile compounds are degraded due to prolonged exposure to high temperatures. This leads to the investigation of the membrane separation processes, such as reverse osmosis (RO) and forward osmosis (FO), as nonthermal technologies for the concentration of liquid foods and beverages. In this study, our objectives were to concentrate fruit juices using FO or a combination of RO and FO and to explore another nonthermal technology that could potentially extend the shelf-life of the concentrate.This work successfully demonstrated the use of FO and combined RO and FO in concentrating Concord grape and cranberry juices, respectively. Both juices achieved >50 °Brix after the concentration process. Different draw solutions (DS) were evaluated at varying concentrations to determine their potential for use in FO. Our results show that potassium lactate and potassium malate with an osmotic pressure of 450 bar or higher and potassium citrate with an osmotic pressure of 350 bar can be used for FO concentration. Most of the physicochemical properties of the juice concentrate, such as total soluble solids, pH, and water activity, were retained during refrigerated storage. However, when the concentrates were reconstituted with deionized water and compared to the original juice, there was a slight increase in pH and reduction in titratable acidity, which can be due to the retention of components into the membrane or migration of the DS into the juice due to the reverse solute flux. Significant color changes were observed during refrigerated storage. The bioactive components, such as total phenolics content and total monomeric anthocyanin, can be retained after processing, but degradation of anthocyanins can occur during refrigerated storage for six months. Lastly, microbial inactivation studies were conducted using high pressure processing at 600 MPa for 3 min (HPP) and high pressure homogenization at 300 MPa (HPH) to extend the refrigerated shelf-life of the juice. Concord grape juice concentrate was inoculated with Salmonella, E. coli O157:H7, L. monocytogenes, and Z. bailii. Salmonella was most resistant to HPP, achieving a >5 log-reduction only after seven days of refrigerated storage post HPP treatment. HPP and HPH showed potential for decreasing Z. bailii to extend the refrigerated shelf-life, with HPP offering a higher reduction after seven days under refrigeration. The results presented in this dissertation offer valuable insights into the nonthermal concentration of fruit juices by reverse osmosis and forward osmosis and its possible refrigerated shelf-life extension through HPP and HPH processing.

Name thesis:degree_name

Ph. D., Food Science and Technology

Level thesis:degree_level

Doctor of Philosophy

Discipline thesis:degree_discipline

Food Science and Technology

Grantor

Cornell University

Year dc:date.issued

2024

Author dc:creator

• Punzalan, Emile

Committee members dc:contributor.committeemember

• Moraru, Carmen
• Gomez, Miguel

• forward osmosis
• fruit juice concentrate
• high pressure homogenization
• high pressure processing
• nonthermal processing
• reverse osmosis

Statement dc:rights

• Attribution 4.0 International

Licence dc:rights.uri

• https://creativecommons.org/licenses/by/4.0/

Language dc:language.iso

en

DOI

https://doi.org/10.7298/v2nr-9874

Dc Identifier Other

ProQuest Submission ID: 14334
ProQuest Publication ID: 31299165

OAI identifier oai:identifier

oai:ecommons.cornell.edu:1813/116554