Bioactive compounds of garlic: a comprehensive review of encapsulation technologies, characterization of the encapsulated garlic compounds and their industrial applicability

Abstract

Background: Garlic contains bioactive compounds such as organosulfur, phenols and saponins with biological activities, namely antioxidant, immunomodulatory, anti-inflammatory anticancer, hepatoprotective, cardiovascular protective, anti-diabetic, anti-obesity, renal protective, neuroprotective antibacterial, and antifungal. However, its organosulfur compounds are chemically unstable and susceptible to degradation, volatilization and oxidation when exposed to harsh environmental conditions, such as high temperature, oxygen and light. Scope and approach: This review describes the main encapsulation methods used to protect bioactive compounds obtained from two derived garlic products (garlic essential oil (GEO) and garlic extract (GE)). The fundamental principles, advantages, disadvantages/limitations of encapsulation methods, namely molecular inclusion, spray drying, complex coacervation, and three types of lipid-based nanoencapsulation methods (nanoemulsions, nanoliposomes and nanophytosomes) are highlighted. Each of these techniques is discussed, since the choice of the most suitable encapsulation technique depends upon the processing conditions involved during the production of nano(micro)particles and its final applications. This review also covers the techniques used to characterize the physicochemical, structural and thermal properties of nano(micro)particles, such as zeta potential, rheological measurements, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM and TEM, respectively). Key findings and conclusions: The spray drying technique revealed the least suitable technique, since the high inlet air temperature involved in the drying process causes loss of garlic heat-sensitive compounds. The GEO and GE nano(micro)particles have high potential to be used as active ingredients in food products, and to act as antimicrobial and insecticide agents. (c) 2021 Elsevier Ltd