Due to the growing concern on the adverse effects on human and environment, more attention in the non-chemical pest control methods is gaining. One of the so-called ‘sustainable’ control practice is to physically freeze the insect and arthropod pests. Aerosol formulation uses propellant gas which is liquefied by pressure, and it lowers the temperature when sprayed by the volume expansion. Using this phenomenon, several ‘freeze spray’ products in South Korea and Japan are commercialized. Nonetheless, unlike other traditional aerosol insecticides, the lack of insecticidal substances in these freeze products allowed them to circumvent legal inspection and registration, no efficacy test result is required in commercialization. In the present study, we examined the insecticidal activity of the freeze spray products against German cockroaches and the housefly in the laboratory condition as well as semi-field tests. The temperature of discharged center mass was –40-45℃, but it had relatively small active range (about 3 cm) which required pinpoint application of the product. Moreover, at least 30 sec and 12 sec of direct contact at 30 cm was required to exhibit >90% of mortality in the cockroaches and houseflies in the lab-based tests, respectively. Semi-field tests indicated an average of 15.8 g and 22.0 g were required to spray to knock down the freely-moving cockroaches and houseflies, respectively. Further utility of the freezing products is discussed.

Spray freeze-drying (SFD) is a comparatively new method of producing biopharmaceutical powder preparations. In this study, Lactobacillus casei (IFO 15883)was spray freeze-dried to obtain a fine probiotic powder. The survival rate of L. casei in the powder after the SFD process was measured using plate agar counting. To improve the survival rate of L. casei during the SFD process, various experimental conditions were carried out. Among five growth media compositions, in Lactobacilli MRS broth with 1% mannose and 0.1% CaCO3, the viability of the freeze-dried powder was not significantly different from that of the initial powder (p>0.05). The most effective air pressure and protective agentduring SFD were 20 kPa and buffered peptone water (BPW), respectively. Scanning electron microscopy (SEM) was applied to estimate the physical structure and properties of the particles. SFD probiotic particles were of various shapes and sizes with porous structures under different SFD conditions. The average diameter of optimized probiotic powder particles with annealing was 24.8 μm. The survival rate of the final SFD probiotic powder under conditions was 97.7%.

In this study, a method to produce a fine volatile powder extracted from shiitake mushrooms using spray freeze-drying (SFD) was investigated. The analysis of the water-soluble aromatic compounds was carried out by headspace solid phase micro-extraction (HS-SPME) coupled withgas chromatography-mass spectrometry (GC-MS). Scanning electron microscopy (SEM) and laser particle size analysis were applied to characterizethe physical structure and size distribution of the SFD-derivedparticles. Eleven key volatile compounds were identified in the extracts of shiitake mushroomspre- and post-SFD. Recoveries of aromatic volatiles ranging from 30.9 - 82.9% were observed in the overall flavor profile results from the powder obtained with SFD. SEM analysis demonstrated that the particles of the aromatic powderwere spherical in nature, having highly porous surfaces andmean diameters of 19.3 μm.