Effect of modified atmosphere packaging on the growth of spoilage microorganisms and Listeria monocytogenes on fresh cheese

Abstract

Queso Fresco has a limited shelf life and has been shown to support the rapid growth of Listeria monocytogenes during refrigerated storage. In addition to improving quality and extending shelf life, modified atmosphere packaging (MAP) has been used to control the growth of pathogenic microorganisms in foods. The objectives of this study were to determine the effects of MAP conditions on the survival and growth of spoilage microorganisms and L. monocytogenes during storage of Queso Fresco manufactured without starter cultures. For L. monocytogenes experiments, cheeses were surface inoculated at ∼4 log cfu/g before packaging. Inoculated and uninoculated (shelf life experiments) cheeses were placed in 75-µm high-barrier pouches, packaged under 1 of 7 conditions including air, vacuum, or combinations of N and CO [100% N (MAP1), 30% CO:70% N (MAP2), 50% CO:50% N (MAP3), or 70% CO:30% N (MAP4), 100% CO (MAP5)], and stored at 7°C. Samples were removed weekly through 35 d of storage. Listeria monocytogenes counts were determined for inoculated samples. Uninoculated samples were assayed for mesophilic and psychrotolerant counts, lactic acid bacteria, coliforms, and yeast and mold. In general, cheeses packaged under conditions consisting of higher contents of CO had lower pH levels during storage compared with those stored in conditions with lower levels or no CO at all. Similarly, the antimicrobial efficacy of MAP in controlling spoilage microorganisms increased with increasing CO content, whereas conditions consisting of 100% N, vacuum, or air were less effective. Mean L. monocytogenes counts remained near inoculation levels for all treatments at d 1 but increased ∼2 log cfu/g on cheeses packaged in air, vacuum, and 100% N (MAP1) conditions at d 7 and an additional ∼1.5 log cfu/g at d 14 where they remained through 35 d. In contrast, treatments consisting of 70% CO (MAP4) and 100% CO (MAP5) limited increases in mean L. monocytogenes counts to <1 log cfu/g through 14 d and ∼1.5 log cfu/g by d 21. Mean L. monocytogenes counts increased to levels significantly higher than inoculation (d 0) on cheeses stored in MAP2 and MAP3 on d 21, on d 28 for MAP4, and on d 35 for cheeses stored under MAP5 conditions. Overall, significant treatment × time interactions were observed between air, vacuum, and MAP1 when each was compared with MAP2, MAP3, MAP4, and MAP5. These data demonstrate that packaging fresh cheese under modified atmospheres containing CO may be a promising approach to extend shelf life while limiting L. monocytogenes growth during cold storage.

Evaluation of the combined effect of temperature and potassium sorbate on physicochemical and microbial quality of modified atmosphere packaged sliced Mozzarella cheese

“…Results are compatible with other studies, since, as LAB are typically facultative anaerobes, it has been reported that MAP may proportionate favorable conditions to LAB growth due to the lack of oxygen in the packaging (Khoshgozaran et al, 2012). Similar behavior was observed for MAP Queso fresco (Brown et al., 2018). In contrast, when considering Mozzarella cheese aerobically stored, it was observed a decrease in the LAB population upon storage (Akarca et al., 2015; Eliot et al., 1998).…”

Lactic Acid Bacteria Adjunct Cultures Exert a Mitigation Effect against Spoilage Microbiota in Fresh Cheese

“…This product was examined twice: first, samples collected in two different seasons, and then the samples used as control during the industrial trial. In the 30 cheese samples, selected after the end of the shelf life from both summer and autumn periods of production, psychotropic Gram-negative bacteria, Enterobacteriaceae and Pseudomonas , represented the dominant population of spoiled cheeses, as already observed [ 33 , 34 ].…”

“…The increasing demand of low-salt and low-fat cheese requires new hurdle technologies approaches to reduce the spoilage microbial communities along the shelf life, particularly by psychotropic Gram-negative bacteria [ 33 , 34 ] that can also trigger antimicrobial resistances [ 35 ]. To address this issue, this study focused on the characterization of the spoilage microbiota of these dairy products and the appraisal of lactic acid bacteria adjunct cultures in limiting the outgrowth of these undesirable microorganisms and consequently cheese defects.…”

“…rhamnosus RH05, and C. maltaromaticum CNB06 that reduced of almost 3 Log CFU/g Enterobacteriaceae and Pseudomonadaceae populations at 8 and 14 °C in a cheese model. The scale-up at industrial level was made adding the three selected strains, alone or in pool, directly in milk for cheese production and studying the development of spoilage during the storage at 8 and 14 °C under MAP, a technology widely used to improve the shelf life of fresh dairy products, limiting the growth of pathogenic and alterative microorganisms [ 34 , 43 ].…”

Active and Intelligent Packaging of Cheese: Developments and Future Scope

“…Oxygen is majorly responsible for cheese spoilage as its presence facilitates the growth of aerobic microorganisms, oxidation of cheese components, nutritional value decline, off-flavors generation, unacceptable color changes, shelf-life reduction and decrease in food safety [32]. Therefore, control of oxygen content inside cheese package is of prime importance.…”