Study of the interaction between pectin and whey protein isolate in the development of extruded and thermocompressed packaging

Abstract

The world consumption of plastic from non-renewable and non-biodegradable sources has been growing a lot, and most of it is improperly disposed of, generating serious environmental problems. Research is being carried out with a focus on biodegradable materials. Pectin (Pec) and Whey Protein Isolate (IPS) are biodegradable, non-toxic, biocompatible, cheap polymers and co-products from the food industry. Considering that most discarded plastics are used to main food and beverage packaging, understanding the consumer's perception of biodegradable packaging is also important. The objective of this work was to study the thermoplasticization with glycerol of pectin by extrusion/thermocompression for films with the addition of IPS, as well as the consumer's perception regarding these films, in order to allow for an industrial application. For this, firstly, thermoplasticized Pec films were produced and characterized via casting and extrusion/thermocompression to prove the effectiveness of thermoplasticization that allows industrial application (extrusion/thermocompression). Then, IPS (0, 5, 10, 15, and 20% by weight) was added to the extruded/thermocompressed Pec films in order to verify the effect of IPS on the properties of the films. In these two steps, the material was submitted to morphological, structural, thermal, water vapor barrier, mechanical and optical characterizations. Finally, these films are presented to consumers via an online questionnaire to assess the perception, acceptance, and purchase intention of materials considering their application as food and beverage packaging. Thermoplasticized Pec showed permeability to water vapor (1.27 - 2.47 g.mm/KPa.h.m²), tensile strength (3.44 - 8.74 MPa), and puncture resistance (43.01 - 230 .75 N/mm) for extruded/thermocompressed films that demonstrated that Pec can be plasticized by casting or by extrusion/thermocompression for film production. Pec and IPS films proved to be homogeneous and without statistical differences between mechanical properties (4.89 – 6.30 MPa of tensile strength, 0.39 – 0.44 MPa of the elastic modulus) regardless of the concentration of IPS. Infrared spectra (bands at 1450, 1540, and 1623 cm-1 indicating the presence of melanoidin) and color analyzes (darker samples with L* values less than 59.29) show an indication of a Maillard reaction. The results indicate that the addition of IPS also results in a material with potential for applications in several industries since it is possible to process using extrusion/thermocompression. The online questionnaire was answered by 556 consumers and the results show that acceptance, purchase intention, and preference are influenced by visual aspects and the consumer prefers lighter films, with less saturated colors and more transparent, films with 0, 5 and 10% IPS. For consumers clear, glossy and, transparent films are thin, fragile, and natural. A variety of food and beverage application possibilities have been raised for Pec and IPS films. The results show that the use of Pec and IPS films as food and beverage packaging is promising both from a physicochemical point of view and in relation to consumer acceptance.