Effects of Industrial-scale Microfluidizer System Processing on the Physicochemical Properties and Nutritional Qualities of Whole-flesh Gannan Navel Orange Pulp

Abstract

In order to solve the problems of flesh loss in the process of navel orange juice extraction and poor suspension stability of navel orange juice, this study used an industrial-scale microfluidizer system (ISMS) to prepare whole-flesh Gannan navel orange pulp, achieving ultra-fine pulp of Gannan navel orange. The effects of different ISMS processing pressures (0, 60, 90, and 120 MPa) on the physicochemical properties (particle size distribution, rheological properties, micro morphology, suspension stability, color, pH) and nutritional qualities (soluble solids, VC, carotenoids, limonin, naringin content) of Gannan navel orange pulp was investigated. The results showed that the particle size of whole-flesh Gannan navel orange pulp gradually decreased, and D[3,2] decreased from 59.77 μm to 26.47 μm when the ISMS pressure increased from 0 MPa to 120 MPa. The pulp particles were refined and dispersed more evenly. In addition, the apparent viscosity of orange pulp gradually increased, and the consistency coefficient K increased from 0.126 to 0.165. Compared with whole-flesh Gannan navel orange pulp without ISMS processing, when the ISMS processing pressure was 90 MPa, the instability index of navel orange pulp was the smallest, decreasing from 0.504 to 0.374, and the precipitation weight ratio was the highest, increasing from 40.80% to 59.48%, indicating that the suspension stability of the whole-flesh Gannan navel orange pulp was the best at this time. In addition, after ISMS processing, the C* of the whole flesh Gannan navel orange pulp gradually increased, and the overall color of the navel orange pulp became more saturated. Moreover, ISMS processing did not affect its pH and total soluble solid content. With the increase of ISMS processing pressure, the VC content in navel orange pulp increased by 11%, the total carotenoid content increased by 15%, and the limonin content increased by 10% after ISMS processing, but the naringin content remained was not changed. In summary, in order to preserve as much nutrients as possible, 120 MPa was chosen as the optimal pressure. This study shows that ISMS can produce whole-flesh Gannan navel orange pulp with good suspension stability and nutritional quality at the industrial level, providing a new pulping route for the navel orange industry.

Keywords

• industrial-scale microfluidizer system
• whole-flesh
• gannan navel orange pulp
• physicochemical properties
• nutritional qualities
• bitter substance