In the first column of this series (See the December issue of FM), we looked at some of the factors that affect a decision to use either a traditional probe thermometer or one of the newer infrared, non-contact thermometers (IRTs). We also discussed some of the proper techniques to use when measuring food temperatures for food safety purposes.
In this concluding column, we’ll consider some additional factors that should be kept in mind when using this new temperature-measurement technology.
Recognize problematic “food density” situations. The temperatures of certain food types are difficult to measure using traditional probe thermometers. Two common examples are peas and macaroni and cheese.
In the case of a product like peas, the probe does not pentrate the actual vegetables, but instead travels through the “lattice” of space created between the individual peas and never makes solid contact with the product. The second product, macaroni noodles, can contain so much air space that, again, a probe thermometer may not make adequate surface-to-surface contact for an accurate reading.
In both cases, infrared thermometers will generally offer more reliable readings. To do so, stir or mix the productto bring material from the interior to the surface just before measurement. The temperature can be read as the material is being stirred.
When measuring the temperature of wrapped items, such as fresh meat, use common sense in evaluating a reading. Ideally, one would probably use a probe thermometer—except that doing so would violate the integrity of the wrap seal. On the other hand, an IR reading will typically reflect both the temperature of the wrap and the meat in contact with it.
Thus, if an IRT is used, make sure you take the reading from an area where a significant amount of the product’s surface is in solid contact with the wrap, not from an area of the wrap with a large air pocket on the other side.
Watch out for heat lamp and other “heat holding” environments. Product on display in holding cases may have been there one minute or 20 minutes; thus, the temperature that is “read” may or may not be the temperature at which the product is actually being held.
A better way to measure such environments is to place a french fry “boat” or similar object in the holding area, let its temperature stabilize, and then take an IRT reading of its surface. This way, you are measuring the contribution the heat lamps will make to hold a product’s temperature, rather than the temperature it may have been right out of the oven.
“Zone out” food storage and display areas. You will often want to know more than just the temperature of the circulating air in a refrigerated cooler or case. An IR thermometer provides an excellent way to take a series of quick “zone” readings from the surfaces of different items in the cooler or case. Take a series of successive scans from objects located top to bottom, side to side or front to back to document how much variance there is in terms of the temperature in different zones. Aluminum cans can provide a good read if they are annodized aluminum; bottles and containers with labels also read well.
Consider the user. Some IRTs feature what are known as “Go/No Go” indicator lights. These will typically flash green when food is within the safe HACCP guideline range and red when it is not. These can be more appropriate for foodservice workers with language barriers or limited experience.
Non food-safety applications. IRTs have many applications in a foodservice environment that are unrelated to food safety. Here are some additional uses to consider:
In pastry and dessert applications. IRTs have a real advantage when it is necessary to measure the temperature of chocolate at various stages in making candy and can help pastry chefs better manage the process of “tempering” chocolate and other ingredients.
Quality control of hot beverage brewing and serving. In coffee preparation, for example, hot water temperatures of over 145°F are often recommended. Some beverages are prepared at even higher temperatures. IRT readings can help you calibrate brewing systems to ensure they are working properly and can also be used to evaluate how the temperature of a served beverage changes after it is poured into and held in different kinds of cups.
Wine temperature measurement. Cold beverage temperatures can be managed in much the same way. This can be important, particularly in white tablecloth situations where fine wines are served (see sidebar).
Better deep-frying. Frying and deep-frying, particularly for sensitive food products, can yield better results if the oil is at exactly the right temperature for the product in question. A quick IRT scan can help you confirm that the oil has reached the optimum temperature before cooking.
Plate temperatures. Plate temperatures have a lot to do with ensuring that hot food is “hot” and cold food is “cold” when served. To ensure that, it can be good practice to spot check plate temperatures on a regular basis, especially during high volume periods, to make sure that plate temperatures meet your criteria.
Equipment troubleshooting. IRT scans of compressors, motors, dishwashers and other kitchen equipment and components can help you identify possible maintenance problems ahead of time. Heat build-up is often an early indicator of potential failure.
Comfort zone tests. Complaints about room temperature can often be traced to hot and cold “spots” created by registers and vents that are mis-directed or mis-adjusted. Temperature scans can sometimes help you identify the source of these problems.
Thermometer maintenance issues. Checking the accuracy of all thermometers on a regular basis is usually recommended, especially if they have been subject to some kind of physical shock. When doing so, follow the specific recommendations of the manufacturer of a given unit.
Also, look for IR thermometers that are specifically sealed to better withstand hand washing. (Note that “hand washable” does not mean a unit is immersible in water! Like most electrical measuring devices, IR thermometers are usually not designed for water immersion.)
Don’t forget to sanitize probes! Finally, in foodservice use, probe thermometers should be sanitized with a sanitizing solution both before and after taking a reading. Health inspectors will often watch for this and it is an easy violation both to make and to avoid.
Will Menchine is a Product Manager for the Raytek FoodPro and FoodPro Plus thermometer product lines.
Time and Temperature
The human sense of taste is complex. What we taste and how we taste it depends not only on food and beverage characteristics like “saltiness,” “sourness” and the like, but also on food texture, “mouth feel,” and in the case of beverages particularly, temperature. Although this is true for all beverages, wines are a special case. While the standard for chilled white wines is fairly easy to meet, wine afficionados can be much more particular about the correct serving temperature of red wines. And because IRT temperature measurements can be taken without physical contact, it can be an ideal way not only to assure that red wines are being served at the right temperature, but as a way of providing a special tableside “touch” to let a customer know that an establishment is committed to his or her dining experience.
Here are some guidelines:
• SERVE FULL BODY REDS at temperatures between 62°F and 68°F.
• MERLOTS and SYRAHS require slightly cooler temperatures: 58°F to 63°F.
• SERVE LIGHT RED WINES at somewhat cooler temperatures—between 54°F and 57°F.
• Pinks and dry white wines are best served at between 46°F and 57°F.
• champagnes and sweet dessert wines should be served at 43°F to 47°F.
Also keep in mind that in matters of taste, opinions differ. For additional advice on the proper temperatures at which to store and serve wine, check these websites: