Brazil is the largest orange producer in the world, surpassing second place, the USA, by more than 50%. The fruit is among the ten most produced agricultural products in the country. Around 80% of the Brazilian harvest is used to produce concentrated juice, which, almost in its entirety, is destined for export to Europe and Japan, involving an operational cost that is between 15% and 20% of its price. Given the increasingly fierce international competition and the importance of the product for the country's economy, it is essential to efficiently control the logistics and transport of concentrated and frozen orange juice destined abroad in order to simplify processes and minimize costs.

The product is generally transported in bulk, in refrigerated trucks, from the processing agroindustry to the ports' cold rooms and the ships are loaded through pipelines, reversing the process at the destination ports.

The largest national processors maintain their own terminals in Brazil and in the main importing countries, using fleets of trucks and ships specially developed to transport concentrated and frozen juice and other citrus products in bulk, in order to guarantee the maintenance of product quality. to your destination.

Such as concentrated and frozen orange juice (Frozen Concentrated Orange Juice – FCOJ) remains a fluid up to minus 18 degrees Celsius, it is pumped to ships at around minus ten degrees, thermal conditions that guarantee its stability.

Fruit juices are made up of two fractions: whey, which contains water and soluble compounds such as sugars, salts and acids; and the pulp, composed of insoluble materials such as fibers, cells, fragments thereof and biopolymers. The high consistency presented by FCOJ, in view of the preponderance of pulp, requires pumping at high pressures, which makes it possible to transport it through the pipelines, which requires a lot of energy consumption. The large volumes transported and the high consistency of the concentrate make it necessary to know the rheological properties of the product to better design equipment and processes. In the case of liquids, rheology studies the factors that influence their flow, which can occur in different ways in relation to flow and time.

Existing studies regarding the reduction of consistency, with a view to facilitating transport and the possibility of using less pressure and consequent reduction in energy consumption, involve chemical methods, such as those using enzymes. Looking for an alternative that does not use chemical reagents or thermal processes, which could contribute to altering the product, food engineer Thiago Soares Leite, guided by professor Marcelo Cristianini, from the Department of Food Technology at the Faculty of Food Engineering (FEA) from Unicamp, researched the possibility of using High Pressure Homogenization (HAP) to reduce product consistency. The research was carried out in the Unit's Emerging Technologies Laboratory.

The technology

HAP is a non-thermal processing technology in which the product is pressurized and forced to pass through a small orifice, which results in a drastic increase in its speed and great friction, so that once the obstacle has been overcome, the fluid finds an atmospheric environment environment, which leads to a sudden expansion, resulting in smaller solid particles due to cell disruption and changes in biopolymer chains. This process causes changes in cellular and biopolymer structures, impacting the size of the particles and the way they interact, thus modifying the rheological characteristics of the product. The result is a noticeably less viscous liquid, which flows more easily and requires less energy in various industrial operations, including transport in pipes.

By using this technology at FCOJ, the researcher aimed to reduce its consistency and change other rheological properties with a view to saving energy in various unit operations such as pumping, freezing and storage. According to him, even small reductions in consistency allow for significant energy savings due to the large volumes of juice processed in Brazil.

When verifying the effect of varying the applied pressure on reducing the viscosity of the concentrated juice, he found that at a pressure of 150 Mega Pascal, which corresponds to approximately 15 atmospheres, the apparent viscosity fell to approximately half of the original value, the size of the particles was reduced, resulting in an increase in the total proportion of small particles in relation to larger ones. The color of the concentrated product remained the same after HAP.

On the other hand, when diluting both the FCOJ originally received from the processing company and the concentrate submitted to HAP, the color was similar, which indicates positively in the production of juice sold in supermarkets, as consumers would resist the consumption of products that did not contain the characteristics they are accustomed to. The author clarifies that sensory analysis would need, in another stage of the study, to be carried out in compliance with technical and ethical protocols. In these two cases of dilution, no differences were observed in the pulp sedimentation time, which would not require a change in consumer habits, already accustomed to shaking commercial juice packaging.  

The study

Thiago explains that, with the reduction in particle size, he sought to understand how this modification interfered with viscosity, reducing it. This required a series of analyzes that allowed the size of the particles to be measured depending on changes in pressure and how these observed changes influenced the viscosity of the fluid, in order to explain the reason for the phenomenon. In other words, he sought to identify and measure what changes occurred in the juice subjected to HAP and contributed to the change in viscosity. Through microscopy it was possible to see the smaller particles and biopolymer chains.

The adoption of a non-thermal process is justified because the temperature can degrade the food and alter the flavor: “The concentrated juice already has a cooked taste resulting from the pasteurization and concentration process and we did not intend to accentuate it”, he explains.

Described here simply, the study involves a series of technical complexities shown in four chapters of the dissertation, written in English and structured in a way that would enable submission to international journals, which is effectively being done.

Conclusions

In general terms, the researcher concludes that the use of HAP has great potential in its application in the FCOJ, as it led to a significant reduction in its consistency, which, under the conditions studied, was reduced by half. This reduction can be attributed mainly to the reduction in particle size and the change in their size distribution, which resulted in lower flow resistance and an increase in the lubricating effect of smaller particles in relation to larger ones.

The results presented in the dissertation suggest the importance of carrying out future studies, such as those relating to checking the concentration of the product during homogenization and, more importantly, the pulp content during this process. The author draws attention to the need to check other parameters, in addition to color and opalescence, such as sensory analysis to verify consumer acceptance of the product. Another important issue is the calculation, through computer simulations, of the real savings that the reduction in consistency brings to the process and which, above all, will enable the balance of its energy balance. As far as possible, he will seek to answer at least part of these questions during his doctorate.

Marcelo's expectations are optimistic: “Reducing the consistency of the concentrated juice by half opened up the expectation of gains in energy consumption. But only through an energy balance will we be able to know whether what is spent to reduce viscosity compensates for the reduction in energy spent on pumping. We believe that the response will be positive, as the HAP process is easy and fast, easily adaptable to equipment in operation that substantially involves pumping from the port to the ship and vice versa, in addition to steps that affect the processing industries”. He believes in gains for exporters and importers.

Publication

Dissertation: “Processing of concentrated and frozen orange juice using high pressure homogenization technology”
Author Thiago Soares Leite
Advisor: Marcelo Cristianini
Unity: Faculty of Food Engineering (FEA)