Elsevier

LWT

Volume 109, July 2019, Pages 467-474
LWT

Reduced-fat biscuits: Interplay among structure, nutritional properties and sensory acceptability

https://doi.org/10.1016/j.lwt.2019.04.027Get rights and content

Highlights

  • Use of raw and extruded bean flours or double emulsion affect biscuit properties.

  • Bean powders have a structuring role in reduced-fat biscuits.

  • Double emulsion gives biscuits with closed structure and high fracture strength.

  • Extruded bean powder gives biscuits with low level of rapidly digestible starch.

  • The role of fat on dough rheology and biscuit liking was assessed.

Abstract

This work aimed at investigating relationships among structure, nutritional properties, and sensory acceptability of reduced-fat biscuits in comparison with a full-fat biscuit (STD). Four reduced-fat formulations were tested: OPT (46.3% fat reduction), an optimized formulation containing polydextrose and resistant starch; RAW and EXTR, obtained by substituting resistant starch with raw and extruded bean powders, respectively; WOW, in which a double emulsion was used instead of shortening. Fracture strength resulted comparable in STD and OPT, but increased for the other samples due to the structuring role of bean protein or the very low amount of fat. Scanning Electron Microscopy images revealed a well-developed protein structure in all samples, except for WOW that presented a more continuous and closed network. EXTR showed the lowest level of rapidly digestible starch and lipid digestibility. RAW showed the highest protein digestibility, significantly different from STD (12.1 ± 2.7 vs 3.7 ± 1.6 g/100 g proteins). Thanks to the holistic approach used, the influence of fat content on dough and biscuit structure as well as on colour was assessed, demonstrating also an effect on nutritional properties and consumers’ acceptance.

Introduction

Fat-replaced biscuits show higher hardness and brittleness and lower crumbliness than the full-fat counterparts, due to a higher development of gluten network (Laguna, Primo-Martín, Varela, Salvador, & Sanz, 2014). The addition of resistant starch (RS) counterbalances texture defects by giving crumblier and less hard biscuits (Laguna, Salvador, Sanz, & Fiszman, 2011; Moriano, Cappa, & Alamprese, 2018). Common bean (Phaseolus vulgaris L.) powders may be exploited as RS-rich ingredients with improved nutritional functionality. The presence of poorly digestible starch confers legumes a low glycaemic index compared to cereal grains, providing benefits to consumers suffering for diabetes or cardiovascular diseases (Hoover & Zhou, 2003). Bean powder is generally produced via soaking, blanching and steam-cooking, thus strongly reducing flatulence-causing oligosaccharides and anti-nutritional factors. Extrusion-cooking has been proposed as an alternative process, being versatile, energy-efficient and time-saving (El-Hady & Habiba, 2003). Moreover, extruded bean powders show higher stability to oxidation, leading to food products more acceptable by consumers (Szczygiel, Harte, Strasburg, & Cho, 2017). However, very few studies investigated the use in biscuits of bean powder, both raw (Sparvoli et al., 2016) and extruded (Ai, Jin, Kelly, & Ng, 2017; Siddiq, Kelkar, Harte, Dolan, & Nyombaire, 2013).

An interesting approach for reduced-fat food development is the application of double emulsions water-in-oil-in-water (W1/O/W2). They consist of an inner water phase (W1) entrapped as small droplets in oil droplets (O) that are, in their turn, dispersed in another aqueous phase (W2). Their main advantage lies in the combination of a structure typical of oil-in-water emulsions, but with a reduced fat content. The main issue is obtaining W1/O/W2 emulsions able to mimic fat behaviour and with a prolonged stability. Gelling of W1 may be a useful strategy (Perez-Moral, Watt, & Wilde, 2014), together with the use of a strong lipophilic emulsifier as polyglycerol polyricinoleate (PGPR) (Muschiolik & Dickinson, 2017). To the best of our knowledge, the use of double emulsions as fat replacers in bakery products has not been studied so far.

The aim of this work was to investigate the relationships among structure, nutritional properties, and sensory acceptability of full- and reduced-fat biscuits, making use of carbohydrate fat mimetics, raw and extruded bean flours, or double emulsion in order to modify biscuits properties.

Section snippets

Biscuit ingredients

Deposited soft-dough biscuits (Table 1) were produced using soft wheat flour ‘00’ (protein content, 10 g/100 g; Molino Dallagiovanna s.r.l., Gragnano Trebbiense, PC, Italy), resistant starch Hi-Maize™ 260 (Ingredion UK Ltd., Manchester, UK; dietary fibre, 56 g/100 g), all-vegetable shortening (Crisco, The J.M. Smucker Co., Orrville, OH, USA), sucrose (Eridania Italia S.p.A, Bologna, Italy), polydextrose (Comprital S.p.A., Settala, MI, Italy), baking powder (Paneangeli, Desenzano del Garda, BS,

Dough rheological properties

Strain sweep curves (Fig. 1A) showed that fat reduction in biscuit doughs prolonged the linear viscoelastic range, in which rheological properties are not deformation dependent (Steffe, 1996), and markedly decreased dough stiffness. This is related to a lower air incorporation rate during creaming. Actually, STD dough density resulted significantly (p < 0.05) lower (0.90 ± 0.01 g/mL) than in the other samples (1.1 ± 0.1 g/mL on average), indicating a higher amount of entrapped air. Similarly,

Conclusions

This work, thanks to the holistic approach used, allowed to investigate the complex relationships among structure, nutritional features, and sensory acceptability of reduced-fat biscuits. The role of fat content and type on dough and biscuit structure was assessed, demonstrating also an effect on nutritional properties. Consumers’ acceptance was in its turn affected by fat content and biscuit structure and colour.

As regards the technologically-advanced ingredients used in fat-reduced biscuits,

Declarations of interest

None.

Funding source

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Acknowledgements

The Authors wish to thank prof. Perry K.W. Ng (FSHN Department, Michigan State University) who kindly provided raw and extruded bean powders. A special thank goes to prof. Alberto Barbiroli (DeFENS, University of Milan) who provided help in protein digestibility interpretation.

References (38)

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