In the quest for sustainability in the juice industry, the recovery and repurposing of industrial by-products have become increasingly crucial. An example of this can be seen in the citrus industry, where solutions from JBT are leading the way in transforming citrus waste into valuable by-products. This journey of turning “waste into worth” not only offers financial benefits but also contributes significantly to environmental conservation.
The Economics and Ecology of Citrus By-product Recovery
Recent studies by the Chemical Engineering Department at the University of São Paulo‘s Polytechnic School and the Sustainability and Low Carbon Center at the São Paulo Institute of Technological Research have compared financial revenue with environmental impact in various industrial processes that add value by recovering by-products from citrus processing waste. The chart below from the article The Modeling and Simulation of Waste Recovery Processes Applied to the Orange Juice Industry estimates the annual revenues achieved from different by-products and their environmental and economic production consequences.
The results indicate that pectin recovery provides the highest economic return, but the greatest impact on the environment. However, d-limonene recovery has an optimum balance being the second-highest revenue and the lowest environmental impact among the five by-products analyzed.
Citrus processing residue represents up to 50-60% of the fruit mass, which is a high-moisture solid fraction that in turn needs to be processed in order to recover valuable by-products for existing markets. While there are various methods to process citrus waste and create profitable by-products, like any industrial process, these methods inevitably impact the environment.
JBT is well-equipped with the necessary expertise and experience to tackle the challenges associated with citrus by-products recovery, ensuring minimal environmental impact. This approach not only maximizes resource utilization but also aligns with sustainable practices in managing citrus waste.
D-limonene from Press Liquor
D-limonene is a fragrant compound found in the essential oil of the citrus peels, particularly in the flavedo (peel) layer, where the oil sacs are located. d-limonene constitutes the majority of citrus peel essential oils. Its pleasant citrusy scent has found applications in cleaning products, perfumes, and as a flavoring in food and beverages. To recover d-limonene, JBT uses a flash distillation system, READYGo™ d-LIMONENE, designed specifically for this purpose.
In the READYGo™ d-LIMONENE system, the press liquor from citrus peels, an oil-bearing stream obtained when processing the citrus peel by using JBT Technology, together with other streams containing oil from citrus processing, is utilized to separate the d-limonene. The different streams are then heated with steam, which breaks the oil stream into oil droplets and water droplets. The oil droplets, containing d-limonene, are then distilled from the water using a flash distillation process. This vapor is condensed and collected as pure d-limonene, ready for use in multiple applications.
An advancement in this process, aimed at avoiding greenhouse gas emissions from natural gas burners, involves using electric steam boilers which are becoming increasingly available at an industrial scale. Combined with photovoltaic solar panels, this can achieve a zero-emission target and enhance environmental sustainability.
Dried Pectin Peel and Pectin Recovery
Pectin is a key component in the food industry, serving as a gelling, cloudy stabilizer and thickening agent in jams, jellies, baby foods, juices, beverages, yogurt, and many other products. Recognizing the value of pectin and its abundance in citrus peels, JBT offers dried pectin peel solutions to extract it.
The process starts with washing the citrus peels in a counter-current flow to remove the sugars (diffusion of soluble solids from the peel into water at a controlled temperature). This process is achieved by using washing tanks, rotatory filters, and screw presses. After the washing steps, the peels are dried in a rotatory dryer at a lower temperature to preserve the pectin quality. Right after the dryer, there is a cooling reel and a baling machine to produce dried pectin peel flake bags.
These pectin-rich flakes can be further processed into commercial-grade pectin, a product in high demand in the food industry. This innovative and sustainable solution reduces disposal costs, contributes to a circular economy in the citrus industry and opens a lucrative revenue stream for processors.
The water used to wash the peels contains natural sugars, which can be extracted to create another recovery stream. This water is sent to JBT’s TASTE Evaporator to obtain these sugars as a concentrated product —fruit natural sugars— and represents an alternative to the wastewater treatment. Due to the built-in ARS (Aroma Recovery System) which comes integrated in JBT’s TASTE Evaporator, the oil phase and any aroma water phase can also be independently recovered and sold in the by-products market.
Feed Mill (Peel Drying – Pellets)
Among the most significant challenges with citrus waste is its high moisture content, which increases weight, making transportation costly and complicates further processing. JBT’s feed mill solution addresses this issue head-on, using an efficient drying and pelletizing process that turns wet peel waste into a valuable by-product — a rich source of nutrition for animal feed or a base for pectin extraction.
The process begins with the addition of lime (calcium hydroxide) to the peel in a screw conveyor, which prepares the peel for further processing. The mixed limed peel is crushed into a hammer mill to keep a homogenous particle size which benefits the drying step. The limed crushed peel, after a minimum residence time to get the pectin chains broken down, is then pressed, using screw presses, to reduce its initial high moisture content, turning it into what is referred to as ‘peel with lower water content’ or press cake. The screw presses separate the solid fraction (press cake) from the liquid fraction (press liquor).
After the liquid fraction extraction, the (press) liquor can be directed into one of two options based on the desired product:
- In the first option, the liquor can be used directly in the production of cloudy products, an ingredient often found in fruit soft drinks to provide cloud stability. This process requires the peel to be processed without adding lime, but on the contrary requires specific enzyme addition and possible pH correction by adding acid such as vitamin C (ascorbic acid). The liquor extraction is accomplished by either counter-current peel washing with hot water and enzyme dosing (diffusion) or mixing the peel, hot water, and enzyme all together into a tank. After the necessary enzyme residence time, the liquor is de-pulped, pasteurized, de-bittered depending on the final recipe and concentrated in a JBT TASTE Evaporator to make the peel cloudy concentrate or just so-called cloudy.
- In the second option, the liquor is concentrated in a Waste Heat Evaporator (WHE), a crucial step where energy in the form of water vapor is removed from the peel and utilized for liquor evaporation. The resulting concentrated molasses are added back to the press cake before final drying, reducing the moisture content of the peel and then enhancing the energy efficiency of the dryer. The molasses also provides additional soluble solids (sugars) content to the final dried peel, which cattle find very tasty.
The press cake, the solid fraction from pressing, mixed with the concentrated molasses, is introduced into a rotating drum dryer. A stream of heated air evaporates the remaining water content, reducing the peel’s volume and leaving behind a dry pulp. This dried pulp then moves to a pellet mill, where it is compressed into pellets, making it easier to handle and transport.
The resulting dried, pelletized citrus waste not only holds high nutritional value as an animal feed, but also significantly reduces waste disposal’s cost and impact.
Embracing a Sustainable Future in Citrus Residue Processing
As the imperative for sustainable industrial practices becomes increasingly pronounced, the innovative strides made by JBT Solutions in the field of citrus by-product recovery are not just a testament to technological advancement but also a beacon of hope for environmental stewardship. This journey from citrus waste to valuable by-products is a clear demonstration of how industrial ingenuity can align with ecological responsibility. By transforming what was once considered waste into economically viable and environmentally friendly products, JBT Solutions sets a precedent for other industries to follow.
The implications of these advancements extend far beyond the citrus industry. They serve as a blueprint for how businesses can turn challenges into opportunities, promoting a circular economy where every by-product is a resource waiting to be harnessed. This approach not only mitigates the environmental impact but also opens new revenue streams, proving that economic prosperity and environmental sustainability can coexist. As industries around the world grapple with the demands of sustainable development, the work of JBT Solutions offers valuable lessons in innovation, efficiency, and environmental consciousness. The future of industrial processing, undoubtedly, lies in such sustainable practices that respect and preserve our planet while fostering economic growth.