Food Safety Tips: How to Use Time and Temperature as Public Health Controls

Consumer demand for nutritious, ready-to-eat food items at grocery stores, convenience stores, and restaurants drive foodservice businesses to handle a large quantity and variety of perishable foods. If prepared or stored improperly, these foods pose the risk of foodborne illness. There are six factors that affect bacterial growth in food: time, temperature, moisture, acidity, nutritional content, and oxygen. Bacteria need the right conditions in order to grow and produce dangerous toxins. To grow, foodborne illness-causing bacteria need food, warmth, and moisture

When bacteria have this fuel, their numbers can double every 20 minutes. To stop bacteria from growing, food operators can control the food temperature, and the amount of time food is resting at that temperature. Businesses that handle many operations such as grocery and convenience stores rely on time and temperature control for safety.

It is complex to control the other factors causing bacteria growth, such as a food’s acidity or moisture. However, along each stretch of the food supply chain, time and temperature can be controlled. Consumers seek out food items from retailers that they trust will deliver a safe and quality product. In order to build this trust, managers and staff must be aware of all of the points along the supply chain where perishable foods are at risk for falling out of time and temperature compliance. In this blog we discuss three tips for reducing the risk of foodborne illness while relying on the time as public health control (TPHC) and temperature monitoring food safety methods.

Tip #1: Know the “Danger Zone”

The temperature danger zone falls between 41° and 135° Fahrenheit. As food temperatures slip into the danger zone, the rate of bacteria growth increases exponentially. Ready-to-eat foods can be safely consumed within a four hour window of entering the danger zone. If they have not been temperature controlled, they should be discarded after four hours. After four hours, most perishable foods will pose a risk of foodborne illness.

When cooling foods, the FDA Food Code recommends a two-stage cooling process. First, food must be cooled from 135° to 70° Fahrenheit within two hours or less. In the second stage, food must be cooled from 70°  to 40° Fahrenheit within four hours or less. Total cooling should not exceed six hours. Cold foods can be served for six hours as long as the food temperature stays below 70° Fahrenheit. Cold foods that warm to over 70° Fahrenheit should be discarded. If you do not have a way to monitor cold food temperatures, you should revert to the danger zone rule of thumb, and discard after four hours. 

Food that will be served hot should be heated to 165° Fahrenheit or higher, within two hours. Hot foods that cool to 135° Fahrenheit or lower should be thrown away after four hours. Hot foods kept in a food warmer should be temperature monitored at least every two hours to ensure they maintain a safe temperature of at least 135°.

Tip #2: Heating and Cooling Methods for Food Safety

With sensitive time windows for heating and cooling, food safety can come down to factors such as heat/cool source and container size. Because foods must be reheated and cooled quickly in order to minimize time in the danger zone, it is important to use appropriate heating equipment such as a microwave, stovetop, or oven. Warming trays or other hot-holding equipment are not recommended for reheating food because these devices will not allow the food to reach a safe temperature within the recommended time frame. Cooling foods can be more complex, warm foods should not be placed directly into the fridge or freezer because they can increase the internal temperature, causing other stored foods to warm. Warm foods can be cooled rapidly using an ice bath, before being transferred to the fridge or freezer.

Smaller containers are recommended for more precise and consistent heating and cooling. For example, grocery stores may serve cold dishes such as potato salad from large serving containers. With large batches of food, the cooling time may extend past the recommended two hour window for reducing internal temperature from 135° to 70° Fahrenheit. Cooling in a large container may keep the food in the temperature danger zone for too long, posing a food safety risk. Transferring large batch hot foods to a shallow pan will expedite the cooling process and minimize time spent in the temperature danger zone. In order to prevent extra moisture, keep containers uncovered during the cooling process, if possible. Discover more safety-driven food packaging tips here: Restaurant Delivery And Food Safety: What Restaurants Need To Know.  

Tip #3: Automation for Precision

When it comes to assessing the risk of foodborne illness, accuracy in temperature control is key. During storage, transport and retail display, food temperatures may fluctuate, and encourage the growth of bacteria. For example, wireless, remote temperature monitoring simplifies the process of assessing the condition of perishable foods, particularly those stored in refrigerators and freezers. An automated system allows changes in equipment temperature to be quickly identified and addressed, before a food safety issue arises. 

Temperatures should be monitored and recorded throughout the cooking, cooling, storage, and retail display processes to ensure the foods reach the proper temperature within the required amount of time and maintain a safe temperature. First, document the temperature of perishable foods upon receiving the shipment of ingredients. This will help gauge whether food entered the temperature danger zone during shipment. Then, use an automated temperature monitoring system through each additional food preparation stage. This will allow for the most accurate assessment of how long food has been in the temperature “danger zone”, and how great the risk of foodborne illness is.

Additionally, some digital temperature-taking systems, such as Squadle,  log temperatures in real time and will alert operators when a food item is too hot or cold. This unsafe temperature could be due to a food item being in the danger zone for four hours. Automated systems prompt users to discard spoiled food for safety.. For time as a public health control (TPHC) compliance, Squadle helps track and monitor food once it is removed from a temperature controlled unit such as a refrigerator or oven, to ensure it is not kept past its “throw away” time. Squadle sends scheduled alerts to grocery and c-store employees through the Squadle HQ app when food items have been sitting on the hot or cold bar for too long. This way, food service operators can resolve the issue immediately, and minimize the risk of foodborne illness to customers.

Two Factor Food Safety Protocol

While many characteristics influence a food’s propensity to grow bacteria, food temperature, and time spent at that temperature are two factors controlled by food service operators. The risk of foodborne illness can be reduced by following “danger zone” four hour protocol, abiding by the FDA Food Code’s heating and cooling time frame recommendations. Using an automated temperature monitoring system with time and temperature controls for safety, can help reduce human error in meeting these food safety standards, by alerting food service operators and staff when food is no longer safe to consume.