Potassium carbonate improves fresh pork quality characteristics

Highlights

• Consumer acceptance of phosphates in meat has declined which necessitates the identification of alternatives

• Potassium carbonate maintained or improved pork quality attributes compared to sodium tripolyphosphate

• The addition of 0.3% K₂CO₃ improved consumer perception of juiciness and tenderness

• Potassium carbonate extracted myosin heavy chain

• Potassium carbonate may function as a sodium tripolyphosphate alternative in fresh pork

Abstract

Meat enhancement strategies like sodium tripolyphosphate (STP) are used to improve fresh meat quality attributes like color, water-holding capacity, and tenderness. However, alternatives are necessary because of reduced consumer acceptance of STP. One alternative is potassium carbonate (K₂CO₃). A study was conducted to evaluate K₂CO₃'s impact on fresh, boneless, center-cut pork loins enhanced with one of five treatments: a negative control, positive control (0.3% STP), and three concentrations of K₂CO₃ (0.1, 0.3, and 0.5%). Loins were cut into chops, stored under simulated retail display, and analyzed for color (L*, a*, b*), pH, cook loss, and tenderness. For each quality characteristic measured, the 0.3% and 0.5% K₂CO₃ maintained redness (a*), decreased yellowness (b*), reduced cooking loss, and maintained tenderness compared to STP. SDS-PAGE analysis further determined that both K₂CO₃ and STP extracted myosin heavy chain. Combined, these data suggest that K₂CO₃ may function as an alternative to STP in the fresh pork industry provided microbial safety and shelf-life are appropriately controlled.

Introduction

Fresh pork quality attributes including color and tenderness are critical for consumer appeal. Improving these attributes is often achieved using enhancement strategies. Enhancement most often occurs when meat is injected with a solution containing water, salts, and/or tenderizers (Lamkey, 1998). These added components are designed to improve color, increase water retention, increase juiciness, improve tenderness, and extend shelf-life (Jones, Carr, & McKeith, 1987; Keeton, 1983; Molins, 1991; Sutton, Brewer, & McKeith, 1997). A variety of phosphate enhancements are available for meat processors including sodium and potassium salts of orthophosphate, pyrophosphate, and tripolyphosphate (Lamkey, 1998). These phosphates can maintain color stability, positively impact pork color by leading to darker, redder, less yellow products, and function as an antioxidant to extend shelf life (Aberle, Forrest, Gerrard, & Mills, 2001; Krause, Ockerman, Krol, Moerman, & Plimpton, 1978). Further, some phosphate compounds can improve pork quality by increasing pH resulting in an increased water holding capacity (Molins, 1991; Offer & Trinick, 1983). As pH is increased, the net charge on the myofibrillar proteins is altered. Specifically, the negative charges on the protein increase while the positive charges decrease. These charges then cause repulsive forces which increase available space and swelling (Mrak & Schweigert, 1984). This swelling increases water holding capacity, decreases cook loss, and therefore increases perceived tenderness due to the increased water (Offer & Trinick, 1983). Recently the mechanism responsible for the increased water holding capacity was further elucidated, as phosphate extracts myofibrillar proteins and dissociates the actomyosin bond (Shen et al., 2016). Because phosphate can cause meat to retain water, its use is regulated in meat at no >0.5% of the final weight of the product in the United States (United States Department of Agriculture - FSIS, 2017). Though, the use of phosphates in meat preparations (i.e. burger, sausages) is generally not allowed by EU legislation (Long, Gál, & Buňka, 2011; Petracci, Bianchi, Mudalal, & Cavani, 2013).

Unfortunately, phosphate enhancement is becoming increasingly unacceptable to consumers who are mandating the food industry reduce and/or eliminate the use of phosphates in meat due to potential health concerns like chronic kidney disease, hypertension, or as a risk factor for cardiovascular disease (Ketteler, Wolf, Hahn, & Ritz, 2013; Mizuno, Mitchell, Crawford, Huang, Maalouf, Hu, Moe, Smith, & Vongpatanasin, 2016; Ritz, Hahn, Ketteler, Kuhlmann, & Mann, 2012). In response, the meat industry has requested the identification and testing of viable phosphate alternatives to maintain or improve meat quality attributes. Proposed phosphate alternatives have primarily focused on replacing the single attribute of improved water-holding capacity derived from phosphate. Suggested options included citrate salts, acetate salts, starches, flours, fibers, hydrocolloids, and exogenous proteins (Petracci et al., 2013). Most of these compounds are able to bind water, but cannot replicate other quality attributes like improved color (colorimeter) and texture (Warner-Bratzler shear force) that also occur with phosphate (Jarvis et al., 2012; Ponrajan et al., 2012; Vasavada & Cornforth, 2006). Phosphates are multifunctional chemicals in meat products and provide improved color, water holding capacity, texture, and function as an antioxidant by reducing oxidation of lipids through calcium sequestration (Jones et al., 1987). Therefore, identifying a phosphate alternative that replicates the functional attributes of phosphate is desirable to the pork industry.

As many processors are beginning to evaluate other ingredients to replace phosphate, one compound that may function as phosphate replacements in meat is potassium carbonate (K₂CO₃; pKa = 10.25) because it is capable of creating an alkaline solution similar to some phosphate compounds. However, the only scientific literature merely suggests the possibility that K₂CO₃ could be used in meat products (Alvarado & McKee, 2007; Chantarasuwan, Benjakul, & Visessanguan, 2011; Prabhul & Husak, 2014). Because K₂CO₃ was recently approved for use in eggs, meat, and some fish products (United States Department of Agriculture - FSIS, 2017), more published information is needed to provide guidance to US meat processors. Therefore, the present study was conducted to evaluate the impact of K₂CO₃ on fresh pork quality including pH, color and color stability (colorimeter: L*, a*, and b*), tenderness (Warner-Bratzler shear force), cook loss, and its ability to extract myofibrillar proteins in comparison to sodium tripolyphosphate (STP). A follow-up study was also conducted to evaluate consumer perception of K₂CO₃ use in fresh pork loin chops.