Improving the quality of liquid smoke by filtration using membranes

Liquid smoke (LS) is getting more attention in many applications, especially food preservation. However, there is still a big problem with the purity of LS. The objective of this study is to improve the quality of LS using membrane filtration. The filtrations were conducted using ultrafiltration or nanofiltration membrane at various pressures. The quality of LS before and after filtration was compared based on their appearance. During the filtration process, LS changed from a dark yellow fluid with a pungent odor to a pale colorless substance with a less smokey odor and a slightly sweet aroma. The color and fragrance parameters of LS before and after filtration using UF membranes were not significantly different. NF membrane filtering had the opposite effect on the appearance of LS. Chemical composition of volatile fraction was studied by GC/MS. Phenols were the predominant aromatic chemicals found in all samples, with LS containing up to 80.8%, 17.53% in treated LS by UF membrane (2 bars), and 48.31% in NF membrane (5 bars). The results proved that the membrane processing can eliminates potentially toxic compounds while still imparting the desired flavors and pleasent aromas of LS.