4. Project Justification
• Client produces cherry concentrate, variety of dried
fruits, and a nutraceutical product purified from
cherry pomace
• Fluctuations in nutraceutical product quality due to
presence of spoilage microorganisms
• Client must reprocess product of reduced quality,
lowering profit margins
• Desire a solution that will be accepted by customers
to maintain trust and positive relationships
5. Problem Statement
The client needs a design that:
• Reduces the amount of spoilage microorganisms in
cherry pomace
• Maintains the positive phytochemical attributes of
cherry pomace
6. Project Objectives
• Reduce yeasts and molds to <1,000 cfu/g
• Reduce total aerobic plate count to <10,000 cfu/g
• Keep loss of anthocyanins <20% of initial levels
• Maintain a cherry pomace production rate of at least
720 lb/hr
7. Constraints
Solution must:
• Keep coliforms to <10 cfu/g
• Operate within client’s processing facility
• Be implemented prior to final packing of the pomace
for transportation to a third-party freeze-dryer
• Cannot adversely affect client’s juicing process,
which operates 24/7 during a six week period in the
months of June, July, and August
• Be accepted by customers
8. Deliverables
• Design that achieves project objectives
• Design proven effective through testing
o Documented test results
• Vendor recommendation
• Economic analysis
10. Screw Heat Exchanger
• Continuously recirculates
particles against heated
surface
• Increases rate and
evenness of heat transfer
to product
• High control of conditions
to which product is
exposed
1
• Reduces the possibility of recontamination and leaving
microorganisms untreated
12. Validation of
Anthocyanin Degradation
• Anthocyanins were extracted
from heat treated and
untreated cherry pomace
• pH Differential Method was
used to quantify degradation
of anthocyanins
• No statistically significant
degradation of anthocyanins
was found pH 1.0 pH 4.5
13. Reduction of
Microorganisms
• Reductions quantified between untreated and heat
treated samples:
o Yeast and mold: 3.46 log reduction
o Total aerobic plate count: 2.07 log reduction
o Coliforms: no coliforms present in either sample,
unable to quantify reduction
2 3 4
15. Economic Analysis
• Discounted payback period
𝑃𝑎𝑦𝑏𝑎𝑐𝑘 𝑝𝑒𝑟𝑖𝑜𝑑 =
𝐶𝑎𝑝𝑖𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 𝑜𝑓 𝑒𝑞𝑢𝑖𝑝𝑚𝑒𝑛𝑡
𝐷𝑖𝑠𝑐𝑜𝑢𝑛𝑡𝑒𝑑 𝑎𝑛𝑛𝑢𝑎𝑙 𝑛𝑒𝑡 𝑐𝑎𝑠ℎ 𝑓𝑙𝑜𝑤
• Economic analysis for system without cooling screw
shows 3 year discounted payback period
• No definitive conclusions about economic feasibility
of system as a whole can be drawn until cost of
cooling screw is included
16. Project Summary
• Proven that design achieves objectives:
o Reduces yeasts and molds to <1,000 cfu/g
o Reduces total aerobic plate count to
<10,000 cfu/g
o Keeps loss of anthocyanins <20% of initial levels
o Maintains a cherry pomace production rate of at
least 720 lb/hr
• Design team recommends that the client move
forward with project using Therma-Flite’s system
based on economic analysis
17. Acknowledgements
• The Client
• Dr. Kirk Dolan and Dr. Dan Guyer – Faculty Advisors
• Dr. Dana Kirk and Dr. Luke Reese – Course Instructors
• Dr. Bradley Marks
• Sunisa Roidoung
• Dr. Leslie Borquin
• Dr. Muraleedharan Nair
• Dr. Elliot Ryser
• Phil Hill
• Nicole Hall
19. Thank you for your
attention!
Do you have any
questions?
7
Editor's Notes
Rachel
Hi everyone, as Dr. Guyer said, we are Project Team 8 and we are the Microbe Busters. Before we get started I would just like to make the disclaimer that our project team is under a non-disclosure agreement, and therefore we are unable to disclose our client, data, or any proprietary information.
Rachel
Rachel
Rachel
Our client produces cherry concentrate, a variety of dried fruits, and a nutraceutical product purified from cherry pomace, which is a term for the cherry skins that are left over from juicing tart cherries. Fluctuations in nutraceutical product quality due to the presence of spoilage microorganisms have at times resulted in a reduction of profit for our client. Customers refuse product of reduced quality, requiring our client to pay to reprocess this product. Therefore, our client desires a solution to this problem that will be accepted by their customers in order to maintain trust and positive relationships.
Rachel
Our problem statement for this project is that the client needs a design that reduces the amount of spoilage microorganisms in cherry pomace and maintains the positive phytochemical attributes of cherry pomace.
Caleb
The following objectives are required for a viable design solution. It must:
Caleb
In addition to reducing molds, yeasts, and aerobic plate count, the solution was constrained to keep coliforms to <10 cfu/g. Other constraints include
Kristine
From communication with our client, we formulated the best fit deliverable based on their criteria. The design that the team will provide a:
Kristine
From preliminary research, the design team initial considered eight different systems. An engineering analysis in the form of a decision matrix was performed on the system design concepts in order to determine which concepts would be the three best options for the design team to further test and investigate. We went through the decision matrix and reasoning for narrowing down these design concepts into three design alternative, which were Heating, RFD, and MAP.
Another decision matrix was again performed on these system design alternatives in order to determine which design alternative would be the best option for the design team to further test, optimize, and implement. Based on the results of the engineering analysis the design team further investigated different heating system design alternatives which are the following: drum dryer, cabinet dryer, rotary dryer, conveyer dryer, fluidized bed dryer and screw heat exchanger. However, before a heat treatment was selected, an extensive literature review of the impacts of heating on microorganisms and anthocyanins was conducted.
We decided upon a heat treatment system because it is proven to inactivate microorganisms. The fatal temperature and time period required are specific to each yeast and mold, so our goal was to treat those microorganisms most difficult to kill. To achieve the desired reduction in microbes, we determined to heat to a temperature of 160 F for a residence time of 5 minutes. Heating is commonly used in the food processing industry, and there are many commercially available heat-treatment systems on the market. Other advantages of heating include low labor requirements, limited impact on rate of pomace production, and increased product shelf-life.
The first five heating system alternatives shown on the last slide require large flows of hot air, so we chose the screw heat exchanger due to its ability to move and heat sticky, damp materials such as cherry pomace more effectively. This diagram shows most clearly how the components fit together; however, the system should actually have two screws. These continuously scrape each other and the sides of the vessel, continuously recirculating particles of cherry pomace against the heated surfaces, thereby exposing every particle to the same heating conditions. This increases the rate and evenness of heat transfer to the product. In addition, we have high control of conditions to which the product is exposed, including moisture, reducing the possibility of recontamination and of leaving microorganisms untreated.
Due to time and resource constraints, a screw heat exchanger was experimentally modeled rather than attempting to design a heated auger system. As can be seen in the pictures on the slide, a screw heat exchanger was experimentally modeled using this apparatus partially submerged in a hot water-bath, created by steam kettles in the Fruit and Vegetable Processing Plant, and rotated using a lab mixer. This apparatus was used in the experimental model of the system because it enabled control over heating and precision of rotational speed. Experiments showed that the pomace did not form an immobile coat on the inside of the rotating container, which was one of the biggest concerns with using this model, and therefore the desired convective heat transfer within the system was maintained. You can see in the picture on the right that the pomace isn’t sticking to everything, but tumbling over itself with the can rotation. Although this experimental model had some limitations, it was determined that it would be an acceptable model to verify that the residence time and temperature effectively reduced microorganisms without significantly degrading anthocyanins.
Kristine
Preliminary testing on cherry pomace was conducted to validate that a temperature of 160F for a residence time of 5 min, that were found from the D and Z values.
Like Caleb stated, in our simulated heating, the samples were rotated in a canister in a steam kettle for 5 minutes at about 160F. To check the anthocyanin degradation, the anthocyanins were extracted using the method from Ibrahim Greiby’s thesis. The extraction consisted of blending the pomace, placing them in a water bath and centrifuging the pomace. Then the samples were analyzed using a spectrophotometer using the pH differential method. The pH differential method is performed by adding 1 mL of the sample and 1mL of the pH buffer. The two pH’s that were used were 1.0 and 4.5. The samples and the buffer were taken at wavelengths of 520nm and 700nm.
From the readings, it was shown that there was a loss of less than 20% of the initial levels and showed no significant degradation.
Kristine
Neofilms, from Neogen, were used to measure the yeast, mold, coliform and aerobic plate count. 10g of each sample were used and diluted with peptone water to a 1:10 dilution. The samples were serially diluted to the appropriate dilution. The films were incubated at the specific times to allow for growth. For the yeast and mold, there was a 3.46 log reduction. Total aerobic plate count had a 2.07 log reduction. the coliforms were unable to quantify a reduction since the pomace started off with so few colonies . Our goal was a 2-log reduction of microorganisms, which was accomplished.
Rachel
Multiple vendors were contacted to investigate options for purchasing a commercially-available screw heat exchanger, and only one vendor was able to provide a quote for a system that would be able to treat our cherry pomace. The vendor Therma-Flite provided the design team with a quote for their Holo-Scru® HSD-13-18-5 system, which is capable of handling the desired throughput of 720 lbs of pomace/hr. The picture on the left shows a photograph of the entire system, and the picture on the right shows how the system uses dual counter-rotating screws to convey the material within the system. The screws are set to a forward and backwards rotation, for example, forward 360 ° and backwards 180 °, which allows for the retention time of the material within the system to be adjusted in order to meet time and temperature specifications.
Rachel
Economic feasibility of Therma-Flite’s system was determined by calculating a discounted payback period, the capital cost of the equipment divided by the discounted net cash flow per year. It is important to note that a component of the system, the cooling screw, was excluded from the quote due to the amount of engineering and design time that is associated with developing a cooling screw. The cooling screw serves to cool the product down to the specified final temperature of -1 °C (30 °F) after it has been heat-treated. This is important because it prevents the potential for microbial re-growth. The economic analysis for the system excluding the cooling screw showed a discounted payback period of 3 years, and therefore it can be concluded that implementing a screw heat exchanger system is likely economically feasible for the client at this time. However, no definitive conclusions about the economic feasibility of the system as a whole can be drawn until Therma-Flite provides the additional cost of including the cooling screw.
Caleb
In conclusion, our design has achieved the following objectives:
Caleb
The design team would like to especially thank the following individuals. This project would not have been possible without the support and assistance that these individuals provided.
