Modified Rotating Reel for Malaxer Machines: Assessment of Rheological Characteristics, Energy Consumption, Temperature Profile, and Virgin Olive Oil Quality

Abstract

The properties of food products are the result of changes produced in raw materials as a result of process treatments. In the olive oil extraction process, these changes can be observed as differences in quality, nutritional characteristics, taste, and flavor, and are especially due to the time and temperature of the malaxation phase. These parameters are closely related to the mechanical design of malaxer machines. In this study, a new reel model for malaxer machines was designed. The new model was incorporated into an industrial malaxer machine and experimental tests were carried out to study the effects of two different reel designs (modified and unmodified profile) on the rheological characteristics of olive paste, the energy consumption of the plant, and the temperature profile inside the machine. The main commercial parameters of the produced olive oil were studied, as well as the extraction yield and the extraction efficiency of the plant. The malaxer machine equipped with the modified reel showed better homogenization of the paste, which led to improved heat exchange and rheological properties. The results of this study showed that a specific modification of the rotating reel can improve the performance of the malaxer in terms of improving the viscosity of the paste, 127,157.67 (mPa sn) for the malaxer with the modified reel at the beginning of malaxation, reaching a final value of 64,626.00 (mPa sn) at the end. The unmodified malaxer showed an initial viscosity coefficient of 133,754.00 (mPa sn) and a final value of 111,990.67 (mPa sn). This led to a reduction in malaxing times, an increase in the work capacity of the plant, and a reduction in total energy consumption and slowed down the oxidative phenomena responsible for the decrease in the quality of olive oil.

Development of a Pressure Control System According to Paste Rheology for Ultrasound Processing in Industrial Olive Oil Extraction

“…The viscosity parameters show a direct correlation with the solid/liquid ratios reported in Table 1; the increase in the solid/liquid ratio between the theses corresponds to a significant increase in apparent viscosity (p < 0.05). The Brookfield viscometer and rheological analysis of the matrix can be used to assess the potential performance of the processing plant (Alexander et al, 2018;Bianchi et al, 2020;Difonzo et al, 2021). Note that the viscosity of the inlet olive paste has been found to vary, and this parameter influences the functionality of the processing machines.…”

An Innovative Malaxer Equipped with SCADA Platform for Improving Extra Virgin Olive Oil Quality

“…EVOO is obtained from the fruit of the olive tree ( Olea europaea L.) solely by mechanical processes [ 5 ]. Among these, malaxation is the crucial step that affects the quality of the product, as numerous studies in recent years have proven [ 6 , 7 , 8 , 9 , 10 ]. During malaxation, the paste is slowly mixed at mild temperatures (generally 25–40 °C) for several minutes (30–45 min).…”

Near Infrared Spectroscopy as a Green Technology for the Quality Prediction of Intact Olives

“…From the technological point of view, the importance of these rapid determinations before oil extraction may lie in the possibility of modulating the extraction systems based on the drupe characteristics and type of desired product. For instance, operative conditions safeguarding the phenolic content can be adopted if phenolic substances are not so high in the drupes or, vice versa, the outstanding phenolic content of some drupes can be lowered if the final product is intended for consumers who do not like bitter/pungent oil [ 12 , 13 ]. Knowing how to set the equipment before starting the process instead of correcting the settings once the oil has been extracted and analyzed might be of interest.…”