HELOISA DIAS BARBOSA

Título da Dissertação: Polpa lavada do suco de laranja como emulsificante em gelado comestível

Orientadora: Profa. Dra. Paula Toshimi Matumoto Pintro

Data da Defesa:15/03/2021

RESUMO GERAL

INTRODUCTION. Orange juice process generates oil emulsion, orange bagasse and pulp wash as co-products. Bagasse and pulp wash represents around 50% of the production and is usually sent to feed mill. Formed by juice cell vesicles, pulp wash contain about 70% of dietary fiber. Application of dietary fibers in food products brings improvement in texture, increase viscosity, gel-forming ability and reduces moisture of products. Ice cream is an aerated emulsion (oil in water) consisted of air cells, ice crystals and fat globules and is thermodynamically unstable. Emulsifiers are added in order to stabilize the emulsion, providing smooth texture and improving melting properties. New approaches to use food ingredients with a sustainable chain and new colloidal particles with partial ability to be wetted by oil and water, co-products like dietary fiber can have capability to act as an emulsifier in food emulsion systems.
AIMS. The objective of this study was characterize physicochemical and technological properties of orange juice pulp wash (PW) and produce ice cream with PW as an emulsifier, verifying the technological and rheological characteristics of the final product.
MATERIAL AND METHODS. Orange juice pulp wash was donated by Citri Agroindustrial S/A (Paranavaí, Paraná, Brazil), dehydrated in a freeze drier, ground and sieved to 60 mesh. PW was submitted to analysis of chemical composition, pH, color evaluation, technological properties (water retention, oil absorption and emulsion activity capacity) and FTIR (Fourier Transform Infrared). Previous experiments were made to select which concentration of PW was necessary to obtain similar behavior to an ice cream made with 1% of commercial emulsifier (CE) through texture profile analysis (hardness and adhesiveness) and overrun measurements. With 0.5% of PW selected, the ice cream control formulation (C) was made and formulations (E0.5, E0.25 and E0) were made with 0.5% of PW and CE reduction. Treatments were analyzed by overrun measurements, melting and rheological properties.
RESULTS AND DISCUSSION. PW is mainly composed by dietary fiber, with 45.91% insoluble fiber and 12.78% soluble fiber. Water retention and oil absorption capacities presented values that can be applied in reduce moisture of products, modify viscosity and texture and also improve stabilization of foods and emulsion. Emulsifying activity of PW can be explained as a function of its water retention capacity, swelling capacity of fibres and combination of Pickering mechanism, allowing to bound oil droplet and get water absorbed. FTIR analysis showed a common structure of fibers, mainly cellulose and lignin. Presence of PW in formulations had more resistance to start melting than control (C), due to water retention effect. All formulations presented pseudoplastic behavior, a good characteristic for ice cream production, with a lower flow viscosity, enabling the mix during production. Higher values for yield stress was displayed for E0.5, E0.25 and E0, than formulation C, explained due the presence of PW, forming greater network structure by swelling of orange fiber. Oscillatory rheology indicates a viscoelastic system for all formulations, meaning elastic modulus (G’) was greater than viscous modulus (G”) and as loss tangent was less than one, formulations represent predominant elastic behavior. Thermo-oscillatory rheology showed steep curves for formulation C and E0, demonstrated by a quicker melting rate analysis.
CONCLUSIONS. Orange juice pulp wash is a source of dietary fiber and had values for water retention, oil absorption and emulsion capacity that allows its application as technological enhancement in food. Replacement of commercial emulsifier by PW improved parameters for ice cream production, being a promising ingredient for food industry.
Key words: dietary fibre; thermo-oscillatory; rheology; melting properties
 

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