Monitoring pH during Meat Processing

Approximately 30 million cattle are raised each year Australia. The conditions during meat processing directly affect the quality of the final beef product; visual and nonvisual cues for quality include juiciness, tenderness, taste, colour, and drip loss. In order to maximise meat quality, both the pH and temperature of the carcass must be monitored during processing; neglect will result in processing conditions called cold shortening and heat toughening.

Cold shortening occurs when the carcass is at a pH greater than or equal to pH 6 while at temperatures equal to or less than 15°C. Heat toughening occurs when the carcass reaches a pH of 6 or lower at temperatures greater than 35°C.  As part of the postmortem physiological breakdown, rigour mortis occurs once the carcass pH decreases to pH 6. Essential for the conversion of muscle to meat, rigour mortis toughens the muscle and eliminates muscle extensibility. Muscles attempt to contract, or shorten prior to rigour mortis; both cold shortening and heat toughening will result in an increase in shortening of muscles, leading to an excessive and undesirable toughening of the meat. Conditions at rigour dictate the carcass temperature should fall between 15 and 20°C to minimise shortening and optimise tenderness.

Meat pH

Glycolysis, another physiological process that occurs postmortem, converts glycogen to lactic acid; the formation and accumulation of lactic acid postmortem reduces the pH of the carcass, permitting rigour mortis to begin. During rigour mortis it is imperative the carcass pH be below pH 6, but above pH 5.2 in order to prevent adverse effects on meat juiciness. Various steps can be taken to control both the pH and temperature to maximise quality. Stress and excessive exercise prior to slaughter, as well as electrical inputs during dressing should be minimised as much as possible to reduce muscle temperatures and prevent excessive lactic acid formation. Administering an ice rinse to the carcass will also assist in decreasing muscle temperatures.

ph-acidifiedThe pH value of meat influences its’ water binding capacity which directly impacts consumer qualities such as tenderness and colour. Lower pH values result in a lower water-binding capacity and lighter colours. Factors such as these can be important when considering how to efficiently produce meat products. For example, when producing dry sausages the meat must have a low water binding capacity so that it can dry evenly.

Depending on the type of the final product and the steps required to get there, pH values will vary throughout the meat processing industry. It is imperative, regardless of the final product, that pH is maintained at a low value to prevent bacterial spoilage and comply with food safety regulations. By monitoring pH values throughout the meat production process, you can ensure the creation of consistent and safe meat products.

98163Meat products can provide a number of challenges for the person that needs to measure pH. Oils and solids from the meat can coat the sensitive glass membrane surface and/or clog the reference junction. The FC2323 pH electrode that is supplied with the HI98163 professional pH meter is designed specifically for measuring pH in meat. Design considerations include a stainless steel piercing blade around conic tip shape probe for easy penetration, an open junction that resists clogging, and a Polyvinylidene Fluoride (PVDF) food grade plastic body that is resistant to most chemicals and solvents, including sodium hypochlorite. It has high abrasion resistance, mechanical strength and resistance to ultraviolet and nuclear radiation. PVDF is also resistant to fungal growth. The FC2323 is an ideal general-purpose pH electrode for meat that connects to the HI98163 meter with a quick-connect, waterproof DIN connector, allowing for a secure, non-threaded attachment.
Besides being supplied with a unique pH electrode for meat, the HI98163 has the Hanna’s unique CAL Check™ feature that alerts the user to potential problems during the calibration process. This is a very important for the food processor since it is likely that the probe will be coated with the solids found in the food product being measured. This coating can easily lead to errors in pH measurement.  By comparing previous calibration data to the current calibration, the meter will inform the user, with display prompts, when the probe needs to be cleaned, replaced, or if the pH buffer might be contaminated.  After calibration, the overall probe condition is displayed on screen as a percentage from 0 to 100% in increments of 10%. The probe condition is affected by both the offset and slope characteristics of the pH electrode, both of which can be found in the GLP data.

bladePressing the “AutoHold” virtual key in measurement mode, the meter will freeze and automatically log a stable reading.  An “out of calibration range” warning can be enabled that will alert the user when a reading is not within the bracket of calibrated pH values.

The log-on-demand mode allows the user to record and save up to 200 samples. The logged data, along with the associated GLP data, can then be recalled or transferred to a PC with Hanna’s HI920015 micro USB cable and HI92000 software for traceability in record keeping for specific product batches. GLP data includes date, time, calibration buffers, offset, and slope, and is directly accessible by pressing the dedicated GLP key.

A contextual help menu based on the screen that is currently being viewed can be accessed at any time by the press of a dedicated button.

The high contrast, graphic LCD screen is easy to view outdoors in bright sunlight as well as in low-lit areas with the backlight. A combination of dedicated and virtual keys allows for easy, intuitive meter operation in a choice of languages.

The compact, durable HI720190 carry case is thermoformed to hold all necessary components for taking a field measurement, including the meter and electrode, beakers, buffer solutions and cleaning solutions.


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