Location: Dairy and Functional Foods ResearchTitle: Characterization of starter-free Queso Fresco made with sodium-potassium salt blends over 12 weeks of 4 degrees C storage
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2017
Publication Date: 5/3/2017
Citation: Van Hekken, D.L., Tunick, M.H., Renye Jr, J.A., Tomasula, P.M. 2017. Characterization of starter-free Queso Fresco made with sodium-potassium salt blends over 12 weeks of 4 degrees C storage. Journal of Dairy Science. doi: 10.3168/jds.2016-12081.
Interpretive Summary: Development of reduced-sodium cheese to meet the demands of health-conscious consumers is challenging when a high-moisture, fresh cheese, such as Queso Fresco (QF), depends on its salt content to obtain it signature flavor and quality traits. In this study, QF made with 2% sodium chloride (NaCl) was compared to QF in which some of the NaCl was replaced with potassium chloride (KCl). It was found that QF containing 1% NaCl and from 0.5 to 1.5% KCl had similar compositions and quality traits during 12 weeks of refrigerated storage. Levels of 1% NaCl and either 1.3 or 1.5% KCl are recommended to obtain the same salty note and shelf-life of the 2% NaCl QF and results in an acceptable reduced-sodium QF alternative.
Technical Abstract: Development of reduced-Na cheese to meet the demands of health-conscious consumers is challenging when a high-moisture, higher pH, fresh cheese, such as Queso Fresco (QF), is dependent on its salt content to obtain it signature flavor and quality traits. This study evaluated the effects of different Na-K salt blends on the compositional, sensorial, microbial, functional, and rheological properties of Queso Fresco (QF) stored for up to 12 weeks at 4 degrees C. QF curd from each vat was divided into six portions and salted with different blends of NaCl-KCl (Na-K, wt/wt): 0.75-0.75, 1.0-0.5, 1.0-1.0, 1.0-1.3, 1.0-1.5, and 2.0-0 (control). Within this narrow salt range (1.5 to 2.5% total salt), the moisture, protein, fat, and lactose contents; water activity; pH; and the non-melt, textural, and rheological properties were not affected by salt treatment or aging (P > 0.05). The total salt, Na, K, and ash contents reflected the different Na-K ratios added to the QF (P < 0.05). Overall proteolysis, the release of casein phosphopeptides, and the level of volatile compounds were affected by aging but not by the salt treatment. Only the 1.0-1.3 and 1.0-1.5 Na-K cheeses had sensory saltiness scores similar to the 2.0-0 Na-K control QF. Aerobic microbial counts decreased between 0.6 and 1.6 log CFU/g by week 2 in cheeses made with greater than or equal to 2% total salt. Aerobic counts recovered between weeks 4 and 10, with counts differing among all cheeses by is less than or equal to 0.7 log CFU/g at week 12. Loss of free serum from the cheese matrix increased steadily over the 12 weeks with higher losses found in QF containing 1.5% total salt compared to the higher Na-K blends. Only minor color differences were noted among the salt treatments when cheese samples were heated and the non-melt characteristic was not altered. In conclusion, KCl substitution is a viable means for reduction of Na in QF resulting in only minor differences in the quality traits and shelf-life of QF made with 1.0% NaCl and 1.0, 1.3, and 1.5% KCl. Only QFs made using 1.0-1.3 and 1.0-1.5 Na-K matched the saltiness flavor of the 2.0-0 Na-K control. The findings from this study will aid cheese producers in creating reduced-Na QF and other high-moisture cheese for health-conscious consumers.