Measuring pH in Meat

- [Instructor] This instructional video will teach you how to incorporate rapid quality measurements into your small-scale processed meat manufacturing establishment. Keeping product quality parameters consistent can lead to increased sales by ensuring more repeat business and expanding your customer base through improved brand reputation. In this video, we will discuss various methods of measuring pH. There are many different types of devices used to measure pH. Meat products are unique when measuring how acidic or basic a sample is. Choosing the correct electrode and meter combination is critical in gaining accurate results. Portable and bench top pH meters will be discussed and demonstrated during this second learning objective. Fermenting sausage products in the olden days was inconsistent, resulting in product that varied from day to day in terms of sensory and quality attributes. As a general rule, product formulations were not written down and measuring pH to determine if fermentation was successful was non-existent. Employees measuring pH should always wear eye protection, a lab coat, or apron, as well as non-latex gloves and close-toed shoes. Accuracy of measuring pH is often affected by traces and conditions that could be changed to increase the accuracy of the results, for example, temperature of the sample being measured or the electrode used to measure the pH. This segment will demonstrate and discuss choosing the appropriate pH meter and electrode for various products to be examined for pH. First, you need to decide what level of financial flexibility your facility has to spend on a pH meter and electrode and how portable the meter needs to be. If you are measuring cold samples, consider utilizing an electrode that calculates and compensates for differences in temperature. The meter chosen should measure in the hundredths place and the accuracy should be at least plus or minus two hundredths. Most pH meters have an automatic calibration function. As long as the automatic process continues through to completion, the results of the calibration will be more useful than trying to calibrate your apparatus manually. When calibrating your meter, be sure to use fresh buffers in the appropriate range for what you are measuring. Typically, for meat products, the meter should be calibrated with pH buffers 4.01 and 7.00. Unless the meter has a temperature compensating probe or function, the buffers should be used at room temperature or approximately 25 degrees celsius. Bench top meters tend to be a greater financial investment although some portable machines can be very costly. Bench top meters are very useful if your facility has a dedicated area or lab to measure the pH of larger quantities of a variety of samples. The electrode is the portion of the meter that is actually inserted into the meat sample or solution being measured. Some electrodes are specific to measuring only liquids, some measure surfaces of products and some are able to be used on a variety of sample types. Portable meters are ideal for the cost-savvy individual or where pH measurements need to be made in a variety of locations in your facility. When deciding upon the appropriate meter for your needs, consider more than just the costs of the meter. Items to consider when choosing a portable meter include the sensitivity of accuracy, the pH range of the meter and if the meter is able to compensate for temperature. When measuring meat samples, choose a location that will be representative of the product being measured. To increase the accuracy of measurements, consider taking duplicate measurements and averaging the results. In this example, notice that the probe placement in the approximate geometric center of the sausage was chosen as a representative location. To duplicate the measurement, the sausage was cut in half and both halves are being measured. Since pH is the measure of acidity of a solution, dry meat products may pose a difficulty when measuring the pH. Dry samples are often a problem, especially if the electrode chosen has a glass tip. Dry meat samples can cause damage to the electrode, which is often a very costly investment to replace. Consider pulverizing dry samples in a sample homogenizer, making a one to four solution of the meat sample and buffered peptone water. For example, a dry sausage with low moisture to protein ratio, may be too hard to accurately sample for the electrode on your meter. Weigh five grams of the sample in a filter bag, add 15 milliliters of buffered peptone water, and pulverize the sample for two minutes prior to measuring the pH of the solution. This will allow for measuring the pH of your product without causing damage to your investment.