How to Eliminate Salmonella Risk in Tahini Production: A Practical Guide for Manufacturers
By Anthony Abi Nader, Food Technology Consultant at Umami Plus. Anthony has taken food products from formulation through pilot scale-up, factory commissioning, and HACCP and quality systems, including low-moisture products such as tahini and sesame-based foods. Last updated: October 2026.
The short answer
To control Salmonella in tahini, you need three things working together: a validated kill step (usually a roasting or pasteurization step proven to deliver a defined log reduction at the coldest point of the product), strict prevention of recontamination after that step (hygienic zoning, dry cleaning, controlled cooling, grinding and filling), and verification through supplier control, environmental monitoring and lot testing. No process can promise zero risk, and finished-product testing alone cannot make unsafe tahini safe. What a manufacturer can do is reduce the risk to a validated, documented level. The most common cause of tahini contamination is not the roasting step itself but what happens after it.
Why Salmonella in tahini is a real manufacturing risk
Tahini is a low-moisture, high-fat food that is usually eaten without any further heat treatment, and tahini is also used as an ingredient in hummus, halva, dressings and sauces, so one contaminated lot can reach many finished products. Salmonella cannot grow in tahini because the water activity is too low, but it can survive in it. A laboratory study of tahini at a water activity of 0.17 found that Salmonella numbers dropped by roughly 3 to 4.5 log over 16 weeks of storage, yet the organism was still present at the end of that period (Torlak et al., 2013). Other work has reported little or no reduction in refrigerated tahini over 17 weeks at high inoculation levels. Survival over months means that a contamination event at the factory can still be a problem at the consumer.
Tahini has also been linked to repeated outbreaks and recalls internationally. Public records describe a 2011 outbreak in the United States of Salmonella Bovismorbificans, outbreaks in 2013 linked to a tahini brand, and a multistate Salmonella Concord outbreak in 2018 and 2019. In the 2018 recall, the manufacturer's probable root cause was reported as cross-contamination, which matches the lesson from the laboratory data: control what happens after the kill step.
1. Understand where Salmonella enters the tahini process
Map the process before choosing controls. Salmonella can enter or return at several points:
Raw sesame seeds. Sesame is often dried and handled in open conditions at origin, so raw seeds should always be treated as potentially contaminated.
Cleaning, soaking and hulling (for hulled tahini). Water contact can reactivate dry, dormant cells. One study found that Salmonella on dry seeds increased by about 5 log after rehydration, so the soaking and hulling stage can raise the microbial load going into the kill step.
Roasting. This is the main kill step in traditional production, and it only works if the time and temperature at the coldest point are enough.
Post-roast cooling, grinding, conveying and filling. The seeds are now ready-to-eat, and any contact with contaminated air, equipment, hands, dust, pests or water can reintroduce the pathogen.
Storage and transport. Poorly sealed containers, condensation and cross-contact with raw materials create new risks.
2. Validate the roasting step
Roasting is often the only Salmonella kill step in tahini production. Laboratory work shows that it can be effective: complete inactivation of Salmonella on sesame seeds (starting at about 6 log) was reported at 110 °C for 60 minutes, 130 °C for 50 minutes or 150 °C for 30 minutes (Torlak et al., 2013). These figures are laboratory results, not a recipe. Your roaster, seed load and moisture level will behave differently.
What affects roasting lethality in a real plant
Product temperature, not oven temperature. Seeds in the center of a thick bed or in a slow-moving zone can stay far cooler than the air. Measure the temperature of the coldest seeds.
Seed moisture and water activity. Research shows that Salmonella survives heat better when seeds are drier. Seed moisture varies by lot and season, so your process must work for the driest, most heat-protective condition you accept.
Bed depth, belt or drum speed and load. Overloading the roaster, uneven flow and dead spots lower lethality.
Warm-up, stops and restarts. Line stoppages and start-up phases are often when seeds receive less heat.
How to validate
Define the target log reduction in your hazard analysis. Many food safety plans for low-moisture foods aim for at least a 5-log reduction, but you must justify the figure for your product and market.
Record the time-temperature profile at the coldest point across the full range of operating conditions and at the worst-case load.
Where possible, confirm lethality with a challenge study using a suitable surrogate organism, run by a qualified laboratory or process authority. Do not introduce pathogens into a production plant.
Set critical limits (minimum temperature, maximum throughput or minimum residence time), monitoring, corrective actions and records.
Re-validate after any change in equipment, seed type or throughput.
If your roasting profile cannot reach the target lethality without ruining flavor and color, consider adding a separate steam or other validated pasteurization step for the raw seeds before roasting.
3. Prevent recontamination after roasting
This is where most tahini safety failures happen. Once seeds are roasted, treat every surface, air stream and person as a potential route back to contamination.
Separate raw and ready-to-eat zones. Physically separate raw seed handling (cleaning, soaking, hulling) from roasted seed handling (cooling, grinding, filling). Use separate tools, color-coded equipment and controlled traffic of people, trolleys and forklifts.
Control air and dust. Use filtered, positive-pressure air in the post-roast area and keep dust from raw seed areas away from it.
Design for hygiene. Use smooth, cleanable surfaces, sloped drains where needed, sealed conveyors and no dead legs where residue can accumulate.
Clean dry where possible. Wet cleaning introduces moisture that can let Salmonella survive and spread in a dry plant. Use dry cleaning (vacuuming, brushing, scraping) as the default in dry areas, and if you must wet clean, dry the equipment thoroughly and validate the process.
Control moisture and condensation. Leaks, wet floors and condensation on cold surfaces are early warning signs.
Manage people. Provide dedicated protective clothing, hand hygiene, footwear changes and training for staff moving between zones.
Control pests and water. Keep a documented pest control program and make sure any water that contacts product is potable and monitored.
Protect finished product. Use clean, closed containers and tamper-evident closures, and prevent condensation during cooling and storage.
4. Control points at a glance
Process step | Main risk | Typical control | Verification |
Seed receiving | Contaminated raw seeds | Approved suppliers, certificates of analysis, origin and lot records, incoming inspection | Supplier audits, periodic lot testing |
Raw seed storage | Pests, moisture, cross-contact | Sealed, dry, pest-controlled storage, segregation | Inspection and pest logs |
Cleaning, soaking and hulling | Growth or spread after rehydration | Limit soak time and water temperature, potable or treated water, drying promptly, sanitation | Water and process monitoring, microbial trending |
Roasting (kill step) | Insufficient lethality | Validated time-temperature at coldest point, critical limits | Continuous temperature recording, periodic re-validation |
Cooling and conveying | Recontamination | Closed, cleanable equipment, filtered air, clean zone | Environmental swabs, air checks |
Grinding and filling | Recontamination from equipment and environment | Dry-clean schedule, hygienic design, controlled access | Environmental monitoring, lot testing |
Storage and distribution | Condensation, cross-contact | Dry, sealed packaging, controlled storage | Complaint and temperature records |
5. Build an environmental monitoring program
Environmental monitoring (EMP) tells you whether Salmonella can reach your product before it ever shows up in a finished sample.
Zone your swabs. Sample food contact surfaces (zone 1), nearby surfaces (zone 2), more distant equipment such as frames and motors (zone 3), and areas outside the process area such as floors, drains and entrances (zone 4).
Sample the right places. Focus on grinders, conveyors, cooling equipment, filler heads, scoops, hoppers, forklifts and doors between raw and ready-to-eat areas.
Test for the pathogen or for indicators. Many plants test for Salmonella directly in the post-roast area and use indicator organisms such as Enterobacteriaceae as a cleaning and hygiene trend.
Define positive findings in advance. A positive result should trigger a written response: intensified cleaning, root cause investigation, extra sampling, product hold and release decisions.
Trend the data. Track results by location and over time so that you see weak spots early.
Use an accredited laboratory and keep clear records.
6. Use product testing correctly
Testing is verification, not a control. A negative result from a few samples cannot prove that a lot is free from Salmonella, because contamination in low-moisture products is usually uneven and at low levels.
Define the lot. Make lot boundaries clear (for example, between cleaning events), so a positive result affects a limited quantity.
Use a documented sampling plan, with enough sample units and sample mass, taken across the whole lot.
Hold and release. Hold product until results are available, if shelf life and logistics allow.
Apply results to decisions. Positive results must trigger investigation, a defined disposition (destroy, re-process through a validated kill step, or other) and notification as required by law.
Do not use testing to replace validation or hygiene. A strong program relies on validated controls first, and tests to verify they work.
7. Manage suppliers and the supply chain
Qualify seed suppliers. Require food safety certification where possible, a documented Salmonella control plan, traceability by lot and origin, and a history of acceptable test results.
Review each lot. Check certificates of analysis, but do not treat them as a substitute for your own kill step.
Diversify carefully. Having more than one qualified supplier reduces supply risk, but every new supplier needs approval before use.
Control tahini used as an ingredient. If you sell tahini to other manufacturers, or buy it for hummus, halva or sauces, remember that their safety depends on yours. Provide specifications, certificates and traceability.
Trace and recall. Keep lot records linking seed lots, roasting batches, filled lots and customers, and test your recall procedure.
8. Document your hazard analysis and food safety system
Include Salmonella as a hazard in your HACCP or HARPC plan, with the roasting step as a critical control point (or process preventive control) and sanitation and supplier controls as supporting controls.
Follow the Codex Code of Hygienic Practice for Low-Moisture Foods and relevant standards from LIBNOR, and confirm requirements with the Ministry of Industry, the Ministry of Economy and Trade and the Ministry of Public Health in Lebanon, as relevant to your product.
If you export, check the requirements of each destination. Importers in the United States and Europe often ask for validation evidence, environmental monitoring records and certification such as ISO 22000, FSSC 22000 or BRCGS.
Train staff, run internal audits and review the plan whenever equipment, seed sources or recipes change.
When to bring in external food safety support
Many manufacturers can maintain a food safety system in house. Consider external help when:
You have never validated your roasting step, or you cannot show evidence of lethality.
You have had a positive Salmonella result in product or in the environment, and need a root cause investigation.
You are building or modifying a tahini line and need hygienic zoning, equipment and process design.
You are preparing for certification, retailer audits or export, and need a HACCP plan, validation evidence and monitoring records.
You supply tahini to other manufacturers who ask for specifications and safety documentation.
You lack laboratory or process authority support for validation studies and environmental monitoring design.
External support is most useful before you invest in equipment and layout, because hygienic design is far cheaper to build in than to retrofit. Umami Plus offers food safety, quality assurance and technical consulting services for manufacturers, from hazard analysis to system implementation.
Project experience
Salmonella risk reduction in hulled tahini production for a food manufacturer (anonymized)
Challenge: The manufacturer produced hulled sesame tahini for retail and foodservice markets and needed to strengthen its food safety controls following a customer audit that identified gaps in the validation of its sesame seed roasting process and the separation of raw and treated materials. The objective was to establish a documented, risk-based control system to prevent Salmonella contamination and support compliance with customer and export requirements.
What we found: The initial assessment identified inadequate documentation of the roasting process's lethality, inconsistent monitoring of critical operating parameters and potential cross-contamination routes between raw sesame handling and post-roasting operations. A review of the process indicated that product temperature and residence time could vary across the roasting equipment, creating uncertainty about treatment consistency. Environmental monitoring also needed improvement, particularly around equipment interfaces, transfer points and areas handling treated sesame. The existing sampling plan did not adequately distinguish between raw-material handling areas and high-hygiene post-treatment zones.
What we changed: We developed a risk-based food safety improvement plan covering the roasting process, hygienic zoning, sanitation and supplier controls. The roasting step was assessed and subjected to a validation protocol using a qualified microbiological challenge study or an appropriately justified surrogate-organism study under worst-case operating conditions. The protocol accounted for the effects of sesame moisture, loading rate, residence time and temperature distribution. We also strengthened the physical and operational separation of raw and treated sesame, revised cleaning and sanitation procedures, introduced risk-based environmental monitoring with defined corrective actions, and improved supplier approval, incoming-material verification and traceability procedures.
Result: The revised control system established a target of at least a 5-log reduction in Salmonella during the validated roasting process, subject to confirmation through an appropriate validation study. Environmental monitoring was structured around risk-based sampling zones, with a target of zero Salmonella detections in designated post-treatment hygiene zones and documented investigation and corrective action for any positive result. The manufacturer gained a more robust, documented basis for process control, product release and customer audit readiness. Any certification outcome, reduction in environmental positives or change in commercial supply arrangements would be confirmed against the actual project records.
Frequently asked questions
How do you eliminate Salmonella in tahini?
You reduce it to a validated level by using a roasting or pasteurization step that is proven to achieve a defined log reduction at the coldest point, preventing recontamination after that step, and verifying with supplier controls, environmental monitoring and lot testing. No process can promise zero risk.
Is roasting sesame seeds enough to kill Salmonella?
Laboratory studies show that roasting can inactivate Salmonella on sesame seeds when time and temperature are sufficient, but real roasters vary. You need to validate your own roaster at the coldest point and the driest seed condition, and then protect the seeds from recontamination.
Can Salmonella grow in tahini?
No, the water activity is too low for growth. However, Salmonella can survive in tahini for months, so contamination that occurs after roasting can remain a risk through shelf life.
Where does tahini usually get contaminated?
Raw seeds are the original source, but many problems come from recontamination after roasting through equipment, air, dust, water, pests or cross-contact between raw and roasted material.
Is testing the finished tahini enough?
No. Contamination is often uneven and at low levels, so a negative sample does not prove a lot is safe. Testing should verify a validated kill step and good hygiene, not replace them.
When should a tahini producer hire a food safety consultant?
Hire one if the roasting step has never been validated, after a positive result, when building or changing a line, when preparing for certification or export, or when customers ask for validation documents.
Talk to us about your project
If you produce tahini or sesame-based products and want to validate your kill step, strengthen your hygiene controls or prepare for audits and export, Umami Plus provides food safety, quality assurance and technical consulting to manufacturers in Beirut, Mount Lebanon and across Lebanon.
Start a project with Umami Plus: tell us about your tahini food safety challenge.
Sources
Torlak, E., Sert, D. and Serin, P. (2013). Fate of Salmonella during sesame seeds roasting and storage of tahini. International Journal of Food Microbiology, 163. https://dx.doi.org/10.1016/j.ijfoodmicro.2013.03.010
Effect of water activity and storage of tahini on the viability of stressed Salmonella serovars. Ciência e Tecnologia de Alimentos. https://www.scielo.br/j/cta/a/4htGRh8YfxsBLQZcWHdPT8n/
Growth, inactivation, and survival of Salmonella on sesame seeds during tahini processing and refrigerated storage of tahini. Illinois Institute of Technology (MS thesis). https://repository.iit.edu/islandora/object/islandora%3A9239/datastream/DC/download
Food Safety News (2012). Government reports 2011 Salmonella outbreak linked to tahini. https://www.foodsafetynews.com/2012/11/government-reports-2011-salmonella-outbreak-linked-to-tahini
Food Safety News (2018). Multiple tahini products linked to Salmonella outbreak; recall initiated. https://www.foodsafetynews.com/2018/11/multiple-tahini-products-linked-to-salmonella-outbreak-recall-initiated/
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