Study of the effect of ultrasound coupled to a tangential filtration pilot on the clarification of jackfruit juice (Artocarpus heterophyllus L)

Jackfruit is an exotic fruit with high nutritional value and significant industrialization potential in the clarified juice (CJ) market. Membrane filtration systems (MFS) make it possible to obtain JC with microbiological stability while retaining their physicochemical (PCP) and nutritional properties. However, problems related to the deposition of solids (clogging) on the membrane surface (Ms) have been reported. The use of Ultrasound (US) coupled to MFS represents an innovative alternative for the reduction of this phenomenon, with the aim of increasing the process performance, but, there isn’t study that has noted their effect on fruit juice clarification, where the main responsible solutes for the clogging are the pectins, however, there isn’t work to date that has been able to highlight them concretely. Studies conducted by LRP and Grenoble ESRF have shown the formation of concentrated layers on Ms and the US effect on MFS using small-angle X-ray scattering (SAXS). In this context, the thesis objective was to study the effect of US coupling to tangential microfiltration (TMF) pilot on process performance, PCP and microbial stability of jackfruit CJ. The work was divided into 5 steps:1) Enzymatic hydrolysis: Six enzymatic treatments (tmt) were applied to the jackfruit pulp (JP), under constant incubation conditions, optimized by the surface response methodology (SRM), where time (t) and concentration (C) were the response of reducing sugars (RS) and viscosity (η). 2) Stabilization of Hydrolyzed Juice (HJ) and JP by Spray Drying (SD): Two maltodextrin concentrations (MC) were selected for SD at constant conditions; drying performance (Dp) and rheological behavior (Rb) were defined the best tmt.3) TMF under US (preventive mode): The SD juices were reconstituted and microfiltered in a laboratory cell, and the influence of several parameters, the pore size (0.1 and 0.22 μm, PVDF planes), the tangential flow rate (0, 5 and 0.3 L / min) and the US application (with/without) (20 kHz, 8 W.cm-2) were studied on the flux and PCP; the best tmt was evaluated in a pilot MFS (TAMI 60 cm) with/without US (35 kHz, 27 W.cm-2). 4) Demonstration of pectin clogging and US action (corrective mode) / SFM by SAXS: TMF experiments of juice-model (12% sucrose, 0.6% citric acid and 0.75% pectin) were performed from optimal conditions to the ESRF on cells coupling filtration/SAXS. Pectin concentration profiles were highlighted.5) Microbiological analysis and PCP of the CJ in the pilot MFS: CJ with/without US were analyzed to identify the US effect on their quality and microbiological flora.The results: Celluzyme® + Pectinex ultra pulp® enzymes (1%, 3 h) allow a 94.5% reduction in η. The SRM indicates that the decrease in η depends on t, because of the pectin content in the JP (3.2-5.8%), the main responsible for the η. On the contrary, the increase of RS depends on C. For the SD the best tmt for JP and HJ was 25 and 50% of CM, with a Dp of 57 and 74% respectively, without affecting its Rb. In the TMF, the US application on the 0.1 μm membrane doubled the flux at low pressures and the 0.22 μm led to an immediate decrease in flux a low TMP, this one induced by blockage clogging. The PCP show that the US doesn’t affect the treated juice and promotes the release of interest compounds. In the pilot MFS the flux increased in the presence of US, but a reduction of carotenoids and microorganisms of JC was observed in connection with the application mode of the US. The SAXS measurements during the TMF of juice-model revealed for the first time the pectin accumulation at the Ms inducing a decrease in the flux, so they highlighted a synergistic effect between the tangential flow rate and the US for the reduction of concentrated layers.