Abstract
Whey represents the major by-product of cheese industry. One possibility to recycle the whey wastes is the use of their globular proteins as a polymer source for the production of biodegradable plastic materials. Whey protein (WP)-based films are usually obtained by protein heat treatment in the presence of glycerol (GLY) as plasticizer at pH 7, a method which would require commercially high costing process. In this work we explored the possibility of producing manageable whey-derived materials without any heat-treatment but under alkaline conditions. The reported results demonstrated that the casting at pH 12 of the unheated WP film forming solutions (FFSs), containing either 40% or 50% GLY, led to produce more resistant and flexible materials than the ones obtained at pH 7. Film opacity was observed significantly increased, being higher in the samples obtained at alkaline pH without WP heating and with higher GLY concentrations. Finally, moisture content decreased with the reduction of GLY content, both in heated and unheated WP-based films, whereas water uptake of the different films prepared at pH 12 did not significantly change.
Highlights
Whey is produced in huge quantities by the dairy industries during the casein coagulation process.Whey can be formed from all types of milk and, in particular, bovine whey is the most common whey produced in the western countries, sharing about 85%–95% of the generating milk volume and containing about 55% of the whole milk nutrients [1]
An ecofriendly treatment of whey, when it is not recycled, is required before its disposal, even because the occurrence of numerous nutrients in whey is considered as a potential resource for the production of different value-added products
Zeta-potential values of the film forming solutions (FFSs) prepared at pH 12 were markedly more negative than those detected with FFSs prepared at pH 7, with an average particle size between 400 and 600 nm regardless of GLY concentrations and heat-treatment
Summary
Whey is produced in huge quantities by the dairy industries during the casein coagulation process. Whey can be formed from all types (cow, goat, sheep, camel) of milk and, in particular, bovine whey is the most common whey produced in the western countries, sharing about 85%–95% of the generating milk volume and containing about 55% of the whole milk nutrients [1]. Whey is responsible for relevant environmental problems due to both its large volume and high organic content, and its disposal into municipal sewers is almost everywhere forbidden. Large amounts of whey remain generally unutilized, and whey still deserves attention from researchers to develop further innovative processes able to provide maximal benefits from this by-product and to limit its environmental pollution impact
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