Pilot Scale Cavitational Reactors and Other Enabling Technologies to Design the Industrial Recovery of Polyphenols from Agro-Food By-Products, a Technical and Economical Overview

Abstract

We herein provide an overview of the most recent multidisciplinary process advances that have occurred in the food industry as a result of changes in consumer lifestyle and expectations. The demand for fresher and more natural foods is driving the development of new technologies that may efficiently operate at room temperature. Moreover, the huge amount of material discarded by the agro-food production chain lays down a significant challenge for emerging technologies that can provide new opportunities by recovering valuable by-products and creating new applications. Aiming to design industrial processes, there is a need for pilot scale plants such as the ‘green technologies development platform’, which was established by the authors. The platform is made up of a series of multifunctional laboratories that are equipped with non-conventional pilot reactors, developed in direct collaboration with partner companies, in order to bridge the enormous gap between academia and industry via the large-scale exploitation of relevant research achievements. Selected key, enabling technologies for process intensification make this scale-up feasible. We make use of two selected examples, the grape and olive production chains, to show how cavitational reactors, which are based on high-intensity ultrasound and rotational hydrodynamic units, can assist food processing and the sustainable recovery of waste, to produce valuable nutraceuticals as well as colouring and food–beverage additives.

Real-Scale Integral Valorization of Waste Orange Peel via Hydrodynamic Cavitation

“…In the recent past, cavitation has emerged as a green extraction technology for natural products, reducing process time and energy consumption, while achieving higher extraction yields, as well as a useful tool for the intensification of food and pharmaceutical processes [25,26]. The growing variety of applications has also stimulated the development of other promising arrangements, such as those based on rotating parts [27] and variants of fixed constrictions based, for example, on vortex dynamics [28], which are in the process of proving the respective affordability and straightforward scalability.…”

“…Real-scale applications of cavitation are quickly spreading in the food and beverage industries, including the processing of food waste [29]. Again, the HC processing of vegetable raw materials, such as grains and hops for beer-brewing [30,31] or plant leaves [32], and its application to the extraction of bioactive compounds [27], offer distinct advantages, such as shorter process times, higher energy efficiency and yields, and enhanced extraction rates. When compared with both conventional techniques and newer ones, including acoustic cavitation sustained by ultrasound irradiation, the HC-based processes showed superior performance, due to enhanced process yields and straightforward scalability [18,33].…”

A review of sustainable and intensified techniques for extraction of food and natural products

“…The contact area of the solid/liquid surface increases when the cavitation bubbles collapse producing shockwaves. 157 The choice of the solvent and the ratio with the plant material are strongly influenced by the nature of the phytocomplex and the type of application. It is noteworthy that the cavitation phenomenon is affected by the physical properties of the solvent; its intensity decreases as vapour pressure and surface tension increase.…”

Novel Affordable, Reliable and Efficient Technologies to Help Addressing the Water-Energy-Food Nexus

“…Basically, HC's outperformance over conventional techniques lies in the fact that physico-chemical and biological reactions and processes can be carried out faster and more efficiently at ambient conditions, and at a lower cost, due to the intense energy delivery at the molecular level in the course of bubbles collapse (Carpenter, Badve, et al, 2017). Consequently, HC processing times were found generally shorter than in conventional extraction techniques, due to the maximization of the mass transfer coefficient generated by cavitation, translating into lower energy consumption (Cravotto et al, 2018). In applications requiring working temperatures above the room level, such as in water disinfection and food pasteurization and sterilization, the heating efficiency can affect remarkably the process yields.…”

“…Moreover, processing costs should be kept as low as possible, translating into affordability for end users, as well as the sensorial properties of the products should be as attractive to the general public as possible. HC processes can lead to enhanced extraction of bioactive compounds in the aqueous phase (i.e., in the end product), by means of the increased release of the respective fraction bound in carbohydrates, lignin, pectin, and proteins, due to the increase of the mass transfer rate and the interphase area (Cravotto et al, 2018;Panda & Manickam, 2019a). Combined with the reduced degradation of the bioactive compounds, due to lower working temperatures (Martynenko & Chen, 2016), higher AA levels could be achieved (Albanese & Meneguzzo, 2019a).…”