Chemistry Labs

Industrial and applied chemistry

Food safety

Use food chemistry and process control to identify biological, chemical and physical hazards, prevent contamination and verify critical controls from receiving through service.

1 Lower secondary2 Upper secondary3 Undergraduate4 Advanced5 Research

IntuitionSafety depends on the whole chain

A safe meal is not produced by one final check alone. Hazards can enter with ingredients, grow during mishandling, survive inadequate processing or reach food through equipment and people. Prevention links supplier controls, hygienic design, separation of raw and ready-to-eat foods, time-temperature management and records that support corrective action.

SchoolThree broad hazard classes

Biological hazards include pathogenic bacteria, viruses and parasites; chemical hazards include cleaning residues, natural toxins and undeclared allergens; physical hazards include glass or metal fragments. Risk assessment considers both the severity of harm and the likelihood of exposure, then selects controls appropriate to the product and process.

UndergraduateHACCP turns analysis into control

Hazard Analysis and Critical Control Point (HACCP) is a preventive system. A team maps the process, identifies significant hazards, chooses control measures, determines critical control points (CCPs), sets validated critical limits, monitors them, defines corrective action, verifies the system and keeps records. Prerequisite hygiene programs remain essential; HACCP is not a replacement for them.

Switch between the process control map and temperature view. Treat limits shown here as teaching examples, not universal legal requirements: applicable rules, food type, equipment and validated process determine limits.

A CCP is a step where control is essential to prevent, eliminate or reduce a significant hazard to an acceptable level. Not every quality check is a CCP. For each CCP, a critical limit must be measurable or otherwise observable, scientifically supported and linked to the hazard—for example a specified product-core time-temperature combination when validated for the product and process.

log reduction=log⁡10 ⁣(N0N)\text{log reduction} = \log_{10}\!\left(\frac{N_0}{N}\right)

A 5-log reduction means a hundred-thousand-fold decrease in the measured target population under specified conditions. It is not a universal guarantee of safety: starting contamination, resistant forms, food composition, measurement uncertainty and post-process recontamination all matter.

Example: Responding to a cooking deviation

A monitored cook step fails to meet its validated critical limit. What should the operator do before the affected lot can be released?

Solution

Hold and identify the affected product, document the deviation, follow the predetermined corrective-action procedure, assess and disposition the lot using qualified authority, restore control, and verify and record the cause and response. Never assume extra cooking is suitable without an approved procedure.

UndergraduateGrowth depends on more than temperature

Microbial growth responds to temperature, pH, water activity, oxygen, nutrients, competing flora and time. Refrigeration generally slows growth but does not sterilize food; freezing often prevents growth while frozen but may leave organisms viable. Thermal lethality depends on organism, food matrix, heating rate and cold-spot history, so a process needs product-specific validation.

log⁡10 ⁣(NN0)=−tDTDT:time for one decimal reduction at temperature T\log_{10}\!\left(\frac{N}{N_0}\right) = -\frac{t}{D_T}\qquad D_T: \text{time for one decimal reduction at temperature }T

In a log-linear model, D_T is the time at temperature T for a one-log reduction under specified conditions. The z-value describes the temperature increase that changes D by a factor of ten. Real survival curves may show shoulders or tails, and parameters are matrix- and strain-dependent; model extrapolation beyond validated ranges is unsafe.

ResearchResearch frontier

References