Changes in Sensory Properties, Physico-Chemical Characteristics, and Aromas of Ras Cheese under Different Coating Techniques

Ras cheese is one of the main hard cheeses in Egypt and is well-known worldwide. Herein, we investigated the potential effects of different coating techniques on the physico-chemical characteristics, sensory properties, and aroma-related volatile organic compounds (VOCs) of Ras cheese over a six-month ripening period. Four coating techniques were tested, including (I) uncoated Ras cheese (the benchmark control), (II) Ras cheese coated with paraffin wax (T1), (III) Ras cheese coated with a plastic film under a vacuum (PFUV; T2), and (IV) Ras cheese coated with a plastic film treated with natamycin (T3). Although none of the treatments significantly affected the salt content, Ras cheese coated with a plastic film treated with natamycin (T3) slightly reduced the moisture content over the ripening period. Moreover, our findings revealed that while T3 had the highest ash content, it showed the same positive correlation profiles of fat content, total nitrogen, and acidity % as the control cheese sample, indicating no significant effect on the physico-chemical characteristics of the coated cheese. Furthermore, there were significant differences in the composition of VOCs among all tested treatments. The control cheese sample had the lowest percentage of other VOCs. T1 cheese, coated with paraffin wax, had the highest percentage of other volatile compounds. T2 and T3 were quite similar in their VOC profiles. According to our GC-MS findings, thirty-five VOCs were identified in Ras cheese treatments after six months of ripening, including twenty-three fatty acids, six esters, three alcohols, and three other compounds identified in most treatments. T2 cheese had the highest fatty acid % and T3 cheese had the highest ester %. The development of volatile compounds was affected by the coating material and the ripening period of the cheeses, which played a major role in the quantity and quality of volatile compounds.