###### Abstract  
This study aimed to compare ozone-microbubble-washing (OM) performed by domestic equipment with conventional water-washing (CW) regarding resultant quality attributes of muscle foods. For this purpose, muscle microstructure and lipid and protein oxidation were evaluated in pork and fish samples after OM and CW treatments. The assessment of muscle microstructure showed that OM treatment did not damage the microstructure of muscle fibers in both pork and fish samples. Thioubarbitric acid reactive substances (TBARS) values were not detected in both treatment groups, and they were substantially below the generally acceptable threshold (1 mg MDA/kg). The methylglyoxal (MGO) level of OM-treated fish samples was significantly higher than that of CW-treated fish samples. However, glyoxal (GO) and MGO levels of OM-treated pork samples were significantly lower than that of CW-treated pork samples. Similar types and sites of oxidative modification and similar numbers of modified peptides, as well as no significant difference in the concentration of total and most of the free amino acids (FAA) between treatment groups, indicated that OM treatment did not accelerate protein oxidation. ozone-microbubbles-washing; ozone; domestic ozone equipment; washing treatment; pork; fish; oxidation +
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removing odor [9], and sanitizing equipment in food plants [10]. In addition, the ability of ozone to remove pesticide residues in foods has intensively been studied. For instance, 1.4 mg/L ozone-water-washing for 30 min was considered as an effective way to remove six pesticide residues and improve shelf life and safety of fresh-cut cabbage [11]. Based on the advantages of ozone treatment in improving microbial safety, degrading pesticides, improving food quality, and extending food shelf life, an increasing number of small domestic ozone equipment has been developed and applied in kitchen cleaning. Previous studies reported that the aerobic plate count value and total viable count reduction ratio of shrimp treated by ozone-washing with domestic ozone equipment was significantly lower during the iced storage of days compared with control (untreated ice-stored shrimp), which indicates that the ozone-washing with domestic ozone equipment is effective against microorganisms as a sanitizer [12; 13]. Furthermore, the combination of ozone with microbubble technology used by some novel equipment has been proven to be an effective cleaning treatment in reducing microbial populations and removing contaminants such as pesticide residues [14; 15; 16]. The primary mechanism of ozone as a disinfectant is to induce strong oxidation. Nevertheless, there are few reports on whether or not ozone-microbubble-washing with the domestic ozone equipment will cause immediate oxidation of nutrients such as fat and protein in foods. Thus, more specific assessments of food qualities using domestic equipment for ozone-water-washing should be considered. However, to our best knowledge, only some studies have evaluated proximate composition (fat, moisture, and protein contents), color and textural attributes (adhesiveness, fracturability, and hardness) [17], and lipid oxidation kinetics of ozone-treated shrimp during cold or iced storage [18]. On the one hand, the previous investigations mainly focus on the impact of ozone-washing by domestic equipment on food quality after a long-term cold or iced storage. Given the practical conditions in conventional households, washed foods are usually eaten immediately. Therefore, more attention should be paid to the immediate impact of ozone-washing with domestic ozone equipment on the quality of foods compared with conventional household washing. On the other hand, although the lipid oxidation of shrimp was evaluated, few studies assessed other attributes, such as protein oxidation, of other foods.