New groundbreaking solution for JNSD production: save up to 67 % energy15 September 2020
This Whitepaper is for anyone in the beverage processing industry who works with juices, nectars, still drinks, or teas, which we will abbreviate as JNSD. In general, we can also refer to these beverages as high-acid products with a pH <4.2.
The solutions outlined in this booklet will be of interest to plant managers, quality managers, technical managers and those working with JNSD in a research or development capacity. This whitepaper is provided by Tetra Pak
A future path for JNSD
The JNSD portion of the beverage industry is stable and conservative in many ways, with industrial practices built up over decades to ensure product safety and efficient production processes. So it isn’t often that something new comes along to shake things up.
As so much of JNSD builds upon the quality of water blended in these beverages, we at Tetra Pak examined and explored how we could reconfigure the processing of ingredients while maintaining product safety and shelf-life – and achieve much lower processing costs as a result. We did this by combining existing technologies – filtration and UV treatment – which can be used to purify water before it is blended with the other beverage ingredients. Our experimentation and innovative equipment and processing parameters yielded extremely satisfying results. While maintaining product safety and quality, this new JNSD line solution can greatly cut down energy-consuming heat treatments – reducing overall energy costs by about 67%. It also reduces water used in cleaning in place (CIP) and sterilization in place (SIP) by about 50%.
The engineering concepts we pilot-tested and verified are relatively straight-forward, as we explain in the following pages. We are now actively seeking beverage producers who would like to test our JNSD line concept in their plants. Please consider joining us on this journey.
The scope of this booklet is JNSD beverages – including teas – that have a pH level <4.2 – in other words, beverages tending to the acidic end of the scale. This is because the natural acidity of fruit counteracts some of the common microorganisms that lead to food spoilage.
In JNSD solutions commonly used today, all ingredients are blended with water to give the final beverage, before going to the pasteurizer for heat treatment, in order to deactivate harmful microorganisms. This can be done with either in-line blending or batch blending. The figure below shows the basic steps in the process, which we can label the current JNSD process.
The problem with this general approach is that the pasteurization requires a great deal of energy to treat the entire beverage volume. This is true even with modern pasteurizers, which are very efficient at heating and cooling, by using regenerative heat.
Moreover, when the system volume is large – 2,000 litres, for example – it means each product change creates a large product loss. In addition, CIP and other cleaning steps may require several system volumes to fully execute, which by themselves require additional water, energy and other resources.
Clearly, this is a process that could benefit from reanalysis.
RETHINKING THE JNSD LINE
If we wanted to transform a JNSD line to make it more energy-efficient and save operating costs, what would it look like?
One approach that has already been tried and commercialized is to add water in the form of steam to the concentrate, followed by dilution with cold water. Other innovative approaches in our industry have focused on achieving required quality levels, but not necessarily saving energy costs.
We decided to take a new approach. We re-imagined the JNSD line by splitting the process into two separate streams, concentrate and water, and treating these two streams differently before blending.
Traditionally, we pasteurize the full volume (concentrate+water) and the most energy-intensive process step is heat treatment.
In our new line concept we pasteurize the smallest possible volume of product, in this case the concentrate. The rest, which is water, is treated separately using more cost-effective aseptic technologies such as filtration, UV light, or a combination of both. Let’s call this design proposal a low-energy JNSD line for the moment.
INNOVATION IN PRACTICE
To test our solution, we began by framing an overall question:
Using a combination of UV and filtration, what would the optimal treatment of water be for producing commercially sterile JNSD and tea with pH <4.2 with minimal energy consumption, investment cost and water consumption?
Our objective was to deliver a production concept for JNSD based on existing or new technologies that would allow quick product changeovers with minimal product losses, reduced water consumption and low total cost of ownership, without jeopardizing food safety.
In order to build a functioning line for the production of commercially sterile JNSD and tea with pH <4.2, we formulated many questions that needed to be researched:
- Which microorganisms should we target?
- What additional treatment (if any) would be needed before and after UV/filtration?
- What are the performance, quality and cost characteristics of commercially available UV lights and filters?
- What type of filter is needed to treat the water?
- What combination of filter and UV would be needed to fulfil requirements on the water?
Formal test requirements
Based on the questions above, we then established formal test requirements for the outputs of any new process. The first two requirements, naturally, were aimed at achieving and maintaining food safety and quality.
Requirement Target threshold
Log reduction for target pathogen microorganism 5 log
Log reduction for target spoilage microorganism 9 log
Reduction in energy consumption costs of the equipment, compared to the current solution, in programme 15-95-25 ºC (regenerative 85%) for still drinks ≥ 40%
Reduction in water consumption for CIP and SIP (sterilization in place), compared to the current solution, in chosen production scenario ≥ 25%
Investment cost compared to a similar conventional line + 10%
Return on investment of the additional investment cost ≤ 6 months
(compared to a similar conventional line)
Commercial sterility is defined by Codex Alimentarius – the FAO/WHO commission that deals with international standards on food safety – as the absence of microorganisms capable of growing in the food at normal non-refrigerated conditions at which the food is likely to be held during manufacturing, distribution and storage. Thus, the microorganism which is most resistant to the proposed treatment and can grow in the final product must be identified. Furthermore, there may be different target organisms when considering UV, filtration, or heat treatment. We consider microorganisms relevant to food safety and food spoilage separately below.
With regards to food safety, there is a legal requirement from the FDA of at least 5 log reductions on the most resistant relevant pathogen. The process used must have a critical control point (CCP) to assure the reduction criterion is met. This CCP should be possible to monitor and control continuously during the process. In a normal pasteurizer the CCPs are temperature and flow (holding time); for UV treatment it is the UV dose; and for filtration it is the integrity of the filter. But while the UV dose can be monitored continuously, ensuring that there are never any pathogens, filter integrity can only be measured after the process is complete. Therefore a solution with only a filter was never an option.
(In the UV light range, UVC irradiation (200-280 nm) is used. It is called the germicidal range as it effectively inactivates bacteria.)
Growth of pathogenic bacteria are limited in JNSD beverages with pH lower than 4.2. Most pathogens cannot grow under these conditions but some, like Listeria monocytogenes, some Salmonella spp and Escherichia coli O157:H7 may survive for some time in the product. These pathogens have a very low infectious dose and thus very few might cause illness in persons at risk. Escherichia coli O157:H7 was identified as the most resistant to UV.
Since pathogens are not possible to use at the test facility in our Product Development Centre in Lund, Sweden, we identified a relevant surrogate organism with similar characteristics. Using Escherichia coli O157:H7 as a reference, we evaluated the UV resistance of three different gram-positive bacteria, also identified as potential spoilage organisms that can be present in water. Evaluation was made in laboratory scale. As a surrogate organism, we chose one able to grow in apple juice that showed a UV sensitivity profile similar to Escherichia coli O157:H7.
The spoilage organism most resistant to UV, and potentially found in water, is the mould Aspergillus brasiliensis. These spores require a very high UV dose to achieve the target of 9 log reductions, which makes it unrealistic to have a solution based on UV light alone, due to the energy costs involved. Therefore a filter was added.
To identify the pore-size of a filter able to achieve a 9 log reduction of Aspergillus brasiliensis, we conducted experiments in laboratory scale using small capsule filters with different pore sizes. In these experiments the load on the filters was 108 cfu/cm2, 10 times higher than what is required to validate a sterile filter. The very high concentration of spores in the feed was necessary in order to show a log reduction of 9.
PILOT PLANT DESIGN
Design based on target organisms
Based on our preliminary work selecting microorganisms, a line solution with only a filter could be used, but each product batch could then not be released until the integrity of the filters was checked. This would counteract the idea of a more flexible production line and increase storage costs of the product before filter integrity was verified.
Similarly, a solution using only UV would result in unacceptably high energy consumption, since a very high UV dose would be needed to treat the high resistance of potential spoilage organisms.
The optimal solution is thus to combine two methods: using a filter to ensure the reduction of spoilage organisms and UV to ensure the required reduction of pathogens.
Developing the test plant
To verify that the combination of UV treatment and filtration of the water gives the required logarithmic reductions of the target organisms, we built a pilot test facility that combined the following components:
• Tank for juice concentrate
• Heat exchanger for pasteurization of juice concentrate
• Tank for water inoculated with target organisms
• UV equipment
• Filter house
• Sample valve for the water
• Aseptic valve
• Aseptic tank
• Aseptic filling machine
In brief, we aseptically blended the inoculated and treated water with heat-treated apple juice concentrate in a tank and filled the apple juice in aseptic 250 ml packages. The packages were then incubated and analysed for commercial sterility. Procedural details follow below.
The plant was first cleaned and then sterilized with steam. CIP took place without the filters mounted. The flow rate corresponded to mean velocities in pipes > 1.5 m/s.
The beverage water was inoculated with a mix of the spoilage organism and the surrogate organism for the pathogen. After adding each organism, a sample was taken to determine the starting value (cfu/cm2). The inoculated water was pumped through the filter and UV equipment at a predetermined flow and temperature. The flow of the water was 1100 l/h, at a temperature of 10°C, and the UV dose was chosen based on the UV sensitivity profiles that were made to find the surrogate organism.
The juice concentrate had to be diluted with water to 50°Bx before it was pasteurized, and cooled to 30°C. The recommended pasteurization temperature for commercial production is 80-95°C, depending on the product. Since it was not possible to fill the aseptic tank with the apple juice concentrate and pasteurized water in parallel it was first filled with the treated water and then with the heat-treated apple juice concentrate. This sequence was chosen to give potential process survivors in the water minimal access to the nutrients in the apple juice.
Treated water and juice concentrate were then blended in the aseptic tank and filled into aseptic 250 ml Tetra Brik® Aseptic packages, which were then incubated at room temperature (20°C) for 3 weeks.
The incubated packages were analysed by checking the apple juice for cloudiness. Any cloudy content was streaked on malt extract agar and MRS (De Man, Rogosa and Sharpe) agar for identification of the organisms causing the cloudiness.
The concentration of Aspergillus brasiliensis spores were 97,000 cfu/ml and the concentration of surrogate organism was 23,000 cfu/ml. A total of 7,858 packages were incubated and checked for growth. Growth was found in only one package, due to Aspergillus brasiliensis. This gave a log reduction of 11.3 with 95% confidence. The reduction of the surrogate organism was >10.6 log.
The required 5 log and 9 log reductions due to food safety and food spoilage, respectively, were thus achieved – and surpassed – using a combination of filter and UV treatments.
COSTS AND ENVIRONMENTAL BENEFITS
We calculated the operational cost for our UV and filter solution, focusing mainly on energy consumption, CIP costs and water consumption. We also evaluated the capital (investment) costs of buying and installing the new equipment needed.
The water consumption in the current solution and the low-energy proposed solution – using UV and filtration to treat the water – was calculated based on the following scenario:
Scenario for calculations
Production time 5 days/week, 20 h/day
Product changes/day 3
Capacity 32,000 l/h
Production efficiency is set to 80% in this calculation, which is a typical line efficiency figure.
This gives a production volume of 2,560,000 litres (32,000 l/h*100 h*80%).
The energy parameters and values used for the cost calculations are the following:
Scenario for calculations
Steam 30 €/1,000 kg
Electricity 0.15 €/kWhr
Cooling factor 3
Production time 20 h/day, 250 days/year
Pump efficiency 50%
dP product 8 bar
dP hot water 3 bar
dP filter+UV 2 bar
Capacity 32,000 l/h
Savings due to Solution Pasteurization Filter + UV Total (k€/year) low-energy line
Current 138 NA 138
Low-energy 34 12 46 92 k€/year / 67%
Table 1: Operating costs
The estimated operating cost for the current solution is 138 k€/year. With the new low-energy solution the operating cost for treatment of the water with filtration and UV is estimated at 12 k€/year and the heat treatment of the concentrate at 34 k€/year, totalling an operating cost of 46 k€/year. This represents a saving of 92 k€/year or 67%, compared to the current solution. (Target was 40%.)
The system volume in the current solution is 2,000 litres. In the new low-energy solution, the system volume for the concentrate portion is 700 litres and for the water portion 300 litres.
The water consumption is estimated to decrease by 50% from 96,000 l/week to 48,000 l/week when implementing the low-energy solution, thus surpassing the target for decreased water consumption. (Target was 25%.)
The customer investment costs for the current and the low-energy solutions are based on a system capacity of 32 m3/h. The choice of UV equipment and effective UV dose were arrived at by extensive experimentation, based on a UV transmission of 90% in the water.
Given the final choice of UV equipment, the additional investment cost to the customer was only 5% more than the current solution. (Target was a maximum of 10%.)
Given the operational savings of 92k€/year, and the cost of typical systems, the additional 5% investment cost is paid back well before the ROI target of a maximum of 6 months. (The exact costs are commercially sensitive.)
The requirements on reduced water and operational cost, as well as payback time less than 6 months on the extra investment, were thus met.
As Tetra Pak food scientists and processing engineers, we set ambitious goals for rethinking and redesigning the traditional JNSD line. This resulted in the design of a new low-energy JNSD line; it split the beverage volume into two separate treatment lines for concentrate and water, which were later blended and packaged.
Preliminary research identified target organisms and determined which levels of filtration and UV treatments would be required to render them harmless.
Combining filters and UV treatment with the correct specifications, we constructed a pilot line to validate this low-energy treatment concept, and ran operational tests involving nearly 8,000 juice packages. The findings were highly successful, as the following table demonstrates.
• The required log reductions due to food safety and food spoilage were achieved – and surpassed – with a combination of filters and UV treatment.
• The requirements on reduced water and operational cost, as well as payback time on investment, were also met or surpassed.
Table 5: Pilot results for quality, performance and cost-benefits
Requirement Target Actual
Log reduction for target pathogen microorganism. 5 log 10.6 log ?
Log reduction for target spoilage microorganism. 9 log 11.3 log ?
Reduction in energy consumption costs of the equipment, compared to the current solution, in programme 15-95-25 ºC
(regenerative 85%) for still drinks. ≥ 40% 67% ?
Reduction in water consumption for CIP and SIP, compared to the current solution, in chosen production scenario. ≥ 25% 50% ?
Investment cost compared to a similar conventional line. + 10% 5% ?
Return on investment of the additional investment cost (compared to a similar conventional line). ≤ 6 months ≤ 6 months ?
The engineering concepts we pilot-tested are relatively straightforward, and can easily be applied by upgrading existing JNSD lines, or building entirely new ones. We are now actively seeking beverage producers who would like to test our low-energy JNSD line concept in their plants, with their beverage formulations. If you share our thirst for excellence and innovation, as well as radical cost savings, please get in touch.
For further advice or consultations on redesigning JNSD lines, or to propose joint research and development projects, please contact:
Maria Norlin, [email protected]