Comparison of steaming and boiling of root vegetables for enhancing carbohydrate content and sensory profile

Johanna Andersson,Mihaela Mihnea,Patricia Lopez-Sanchez,Carolin Menzel,Gonzalo Garrido-Bañuelos,Marion Bergdoll,Francisco Vilaplana

doi:10.1016/j.jfoodeng.2021.110754

Abstract

Root vegetables have unique techno-functional and nutritional properties however, their use in processed foods is limited to a few species, partially due to a lack of knowledge related to the impact of thermal treatments on the sensory properties. This study investigated the effect of steaming and boiling on the microstructure, mechanical properties, and sensory profile of three model root vegetables with distinct carbohydrate composition: Jerusalem artichoke ( Helianthus tuberosus L.), parsnip ( Pastinaca sativa ), and beetroot ( Beta vulgaris ). Thermally treated Jerusalem artichoke and parsnip showed higher content of cell wall polysaccharides, particularly β-glucans (e.g. cellulose) and pectic components, compared to raw. Steaming produced more cell shrinkage and loss of cell-cell adhesion than boiling, leading to softer vegetables. Processed beetroot showed loss of cell turgor and drastic softening but not clear changes in overall carbohydrate content. The scores for several flavour and in-mouth attributes were higher for steamed vegetables compared to boiled. Our results give insights on the processability of root vegetables towards products with enhanced sensory and nutritional properties. • Steaming and boiling increase dietary fibre in Jerusalem artichoke and parsnip. • Steamed vegetables are softer, have larger cell shrinkage and loss of cell adhesion. • Textural changes in processed beetroot are not related to total carbohydrates. • Flavour and in-mouth sensory attributes scores are higher for steamed vegetables. • Results give insights to use root vegetable pieces in processed foods.

Highlights

Root vegetables can grow outdoors under different climates, including the harsh conditions of Nordic and tropical countries
In this study we investigated the impact of steaming on the carbohydrate composi tion, mechanical proper ties and microstructure of three model root vegetables (Jerusalem artichoke, parsnip and beetroot), which are not commonly used in processed foods
The values of the Young’s modulus for the raw materials were 7.12 ± 0.81 MPa for Jerusalem artichoke, 3.30 ± 0.18 MPa for parsnip and 4.60 ± 0.34 MPa for beet root (Table 1), this indicates that parsnip was more elastic than Jerusalem artichoke and beetroot

Summary

Introduction

Root vegetables can grow outdoors under different climates, including the harsh conditions of Nordic and tropical countries. From a nutritional point of view, root vegetables are rich in dietary fibre i.e cell wall polysaccharides and antioxidants, which are related to positive effects on human health reducing the risk of cardiovascular diseases and type 2 diabetes (Bach et al, 2015a; Causey et al, 2000; Georgiev et al, 2010; Ninfali and Angelino, 2013; Ninfali et al, 2005; Rubel et al, 2018). In order to better exploit the techno-functional and nutritional properties of root vegeta bles the relationship between processing conditions, composition and microstructure must be elucidated. Alternative ther mal methods such as steaming, in which the heat transfer is more uni formly distributed compared to boiling in water, could help reduce those losses and retain the full techno-functional and nutritional value of root vegetables

Methods

Results

Conclusion