A systematic analysis on tomato powder quality prepared by four conductive drying technologies

Jun Qiu,Maarten A.I Schutyser,Parag Acharya,Doris M Jacobs,Remko M Boom

doi:10.1016/j.ifset.2019.03.013

Jun Qiu, Maarten A.I Schutyser + Show 3 more

Open Access

https://doi.org/10.1016/j.ifset.2019.03.013

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Abstract

Abstract Four pilot-scale conductive dryers, namely a vacuum drum dryer (VDD), a drum dryer (DD), an agitated thin film dryer (ATFD) and a refractance window dryer (RWD), were used to dry tomato puree. Drying induced colour differences between the reconstituted puree and the original puree and strongly affected the volatile and non-volatile profiles of the powders. Principal component analysis (PCA) identified four separated groups corresponding to the different drying methods, indicating that the drying methods caused significant variance in compound profiles. Subsequently, pairwise comparison of different dried powders was performed by partial least square discriminant analysis (PLS-DA). This resulted in a selection of discriminative volatile and non-volatile markers. RWD and VDD produced powders with high volatile markers that may be related to aroma retention. Conversely, DD dried products contained more non-volatile markers that can be related to taste perception. ATFD processed powders had a lower level of discriminant compounds. Industrial relevance Tomato products are frequently thermally processed and dehydrated. However, processing negatively affects the sensory quality of tomato products. In this study, four conductive drying processes, i.e. vacuum drum drying (VDD), drum drying (DD), agitated thin film drying (ATFD) and refractance window drying (RWD) were studied for being energy-efficient drying methods, while suitable for mild (e.g. due to the reduced pressure) drying of pastes and slurries, such as tomato puree. The pilot-scale drying experiments and subsequent statistical analyses of results on quality markers contributed to unravel the impact of the different conductive drying technologies on tomato powder quality. This study may be considered a starting point for selection of conductive drying technologies for the efficient production of high quality tomato powders and other vegetable powders.

Highlights

Tomato (Lycopersicum esculentum) is a healthy source of nutrients such as fibres, proteins, vitamins, lycopene and other antioxidants (Gahler, Otto, & Böhm, 2003; Qiu, Vuist, Boom, & Schutyser, 2018)
For drum dryer (DD) and vacuum drum dryer (VDD), significant amounts of water were evaporated during boiling in the feeding pool
All the drying methods resulted in a change in colour when comparing the reconstituted and the original tomato puree

Summary

Introduction

Tomato (Lycopersicum esculentum) is a healthy source of nutrients such as fibres, proteins, vitamins, lycopene and other antioxidants (Gahler, Otto, & Böhm, 2003; Qiu, Vuist, Boom, & Schutyser, 2018). Conductive drying is a good option to dry tomato puree into powders, as it is energy efficient and especially suitable for pastes, slurries and concentrated solutions (Devahastin & Mujumdar, 2006; Sahni & Chaudhuri, 2012). Throughout the years different types of conductive dryers have been developed, such as drum dryers (DD), agitated thin film dryers (ATFD) and refractance window dryers (RWD) (Fudym, Carrère-Gée, Lecomte, & Ladevie, 2003; Nindo & Tang, 2007; Pawar, Patil, Mujumdar, & Thorat, 2011). Drum drying is one of the more energy-efficient drying techniques as it consumes on average 40% less energy than spray drying (Nindo & Tang, 2007), but the product is exposed to the boiling temperature and eventually to the wall temperature, which can result in severe quality loss. The thermal damage can be alleviated by applying reduced pressure to lower the boiling temperature, the capital

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