Subcritical hydrolysis: An approach to valorize ice cream wastewater

Document Type

Abstract

Publication Date

2019

Location

2019 American Dairy Science Association Annual Meeting: Cincinnati, Ohio

Publisher

American Dairy Science Association

Journal

Journal of Dairy Science

Volume

102

Issue

Suppl.1

Pages

40

Language

en.

Keywords

ice cream, wastewater, subcritical hydrolysis

Abstract

Ice-cream manufacturers generate large volumes of wastewater (WW) through the daily cleaning programs. Identifying profitable valorization methods for WW treatments are playing a decisive role in sustainability of dairy and food industries. Treatment of ice cream WW through subcritical hydrolysis is one of the promising methods to overcome the environmental concerns deriving from dairy effluents as well as converting them with further utilization as platform chemicals. In this study, samples of ice cream WW were collected from university dairy plant during 6 weeks of production. First, physicochemical properties of WW samples were analyzed as follows: total solids (0.64 ± 0.01 to 2.05 ± 0.01 g·100 g−1), total protein content (6.81 ± 0.81 and 9.67 ± 0.35 g·100 g−1 on dry matter basis), and pH values (from 2.99 ± 0.02 to 6.99 ± 0.03). Untreated WW samples also possess high organic load (biological and chemical oxygen demands of 38.2 ± 0.57 g·L−1 and 289 ± 2.83 g·L−1, respectively). The hydrolysis of ice cream WW was carried out in a continuous stirred-tank at nitrogen flow of 40 bar and 230°C. After a 200 min reaction, the recovered WW hydrolysates were characterized by measuring the degree of hydrolysis (DH), antioxidant activity via measuring free radical scavenging (2,2-diphenyl-1-picrylhydrazyl or DPPH) method, as well as determining antihypertension (ACE) activity. Additionally, the peptide fractions of recovered hydrolysates were determined to attribute their proportions to relevant functional activities. The maximum value of DH (31.75 ± 0.53%), and percentage of remained DPPH (15.21 ± 0.44%) as well as ACE inhibition (96.38 ± 1.17%) showed the efficiency of subcritical hydrolysis to valorize ice-cream WW and convert it to value-added materials. The peptide identification showed the high ratio of glutamic acid and proline confirmed the relevant antiradical and antihypertensive activities of recovered hydrolysates. The outcomes present the potential of subcritical hydrolysis to convert ice-cream WW into nutraceutical compounds that can be utilized as functional food ingredients and pharmaceuticals.

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