Page 36 - FoodFocusThailand No.211 OCTOBER 2023

SPECIAL FOCUS

Table 1 Comparison of Ozone Slurry Ice (OSI) and Flake Ice (FI)

Property Ozone Slurry Ice (OSI) Flake Ice (FI)
Source material Produced from seawater, yielding small ice crystals Produced from freshwater having in large ice
with a soft texture. crystals with a harder texture.
Skin integrity of aquatic Maintains skin integrity; pressure or tearing during Puts skin integrity at risk; susceptible to pressure-
animals storage and transport is minimal. induced tearing during storage and transportation.
Temperature range Maintains a temperature range of -0.5 to -2°C. Typically hovers at 0.5°C or higher.
Temperature reduction Rapidly lowers the temperature of aquatic animals, Slower temperature reduction often results in
capability ensuring they stay within a storage range of 0 to aquatic animals sustaining 1°C or higher
-1°C. temperatures during storage.
Preservation of sensory Effectively preserves the color, odor, and taste of Rapidly alters the color, odor, and taste of aquatic
attributes aquatic animals. animals.
Microbial control Contains ozone, serving as an agent to impede or Lacks active substances that deter or eradicate
annihilate microbial growth. microorganisms.

Ozone Slurry Ice Improves the Efficiency of Thai researchers conducted experiments using Ozone Slurry
Preserving Seafood Ice (OSI) to preserve sea bass for 14 days. They found that fish
Slurry Ice (SI) is an innovative cooling technique derived from preserved in Flake Ice (FI) had a higher overall microbial count
seawater that presents a sub-zero temperature suspension compared to those preserved in OSI. This significant finding
(-1 to -2 °C) as its hallmark for preserving the freshness of indicates that the use of ozone in conjunction with Slurry Ice is
seafood products. SI boasts a distinct advantage in its swifter effective in controlling microbial growth. According to the Ministry
cooling rate when contrasted with Flake Ice (FI), concurrently of Public Health (No. 416) in 2020, which sets the quality and
mitigating the risk of physical damage to aquatic organisms due standards, criteria, and testing methods for microorganisms in
to the presence of ice particles in slurry form. Notably, the food that can cause diseases, seafood consumed raw or
preservation of aquatic organisms using ozonized liquid ice minimally processed and packaged for sale, such as fish, shrimp,
preserves their chemical, sensory, and antimicrobial attributes. squid, sashimi, etc., must not contain Salmonella spp. in 25
Using Slurry Ice (SI) to chill seafood is more efficient in grams of flesh. Additionally, Staphylococcus aureus, Bacillus
preserving food than traditional Flake Ice (FI), which is a cereus, and must not exceed 100 CFU
conventional chilling technique. This is because liquid ice in 1 gram of flesh. From the results, it was found that sea bass
provides deep chilling, as shown in a report by Saramac Ltd. It preserved in Ozone Slurry Ice (OSI) did not contain Salmonella
was found that liquid ice can rapidly lower the temperature and spp. Furthermore, the levels of Staphylococcus aureus, Bacillus
induce unconsciousness and death in mackerel within a cereus, and Clostridium perfringens remained within the
remarkably short time, often within 20 seconds. This results in established standards throughout the 12-day preservation period.
the preservation of adenosine triphosphate (ATP) levels before Therefore, fresh sea bass preserved in Ozone Slurry Ice (OSI)
death, which is significantly lower than in fish that experience is safe for consumption and passed the criteria announced by
a more prolonged and distressing death (agony death). the Ministry of Public Health. In sensory evaluations conducted
Experiments conducted at the Hokkaido Industrial Technology using the 9-point Hedonic scale by food experts from Japanese
Laboratory further confirmed these findings, revealing that the and Thai restaurants, it was observed that these experts
ATP content in mackerel that underwent distressing death was continued to accept sea bass preserved in Ozone Slurry Ice
lower than those that experienced rapid death in Slurry Ice (SI), (OSI), whether in raw or cooked form, even after the extended
while the concentration of lactic acid was significantly higher. 12-day preservation period. This indicates the safety and suitable
This scientific evidence underscores the impact of Slurry Ice quality of sea bass preserved using Ozone Slurry Ice (OSI) for
(SI) and ozone on seafood freshness preservation. consumption.
Ozone Slurry Ice Machine by a Thai Research Team to This experiment is according to the study of Campos et al
Mitigate the Cost of Importing from Abroad In a collaborative (2005), it was found that ozone can slow down microbial growth
endeavor between the Faculty of Fisheries at Kasetsart in fish preserved with Ozone Slurry Ice (OSI). Moreover, the
University and a private research entity, a pioneering Ozone Ozone Slurry Ice (OSI) also prolongs the shelf life by up to 60%.
Slurry Ice (OSI) machine has been meticulously developed. Some studies reported that the combination of ozone, whether
This innovative technology promises to revolutionize seafood in normal water or NaCl solution, effectively inhibited several
preservation. The comparative properties of OSI in contrast to microorganisms such as Vibrio cholerae, Escherichia coli,
traditional freshwater-based Flake Ice (FI) are elucidated in the Salmonella typhimurium, Vibrio parahaemolyticus and
ensuing table: Staphylococcus aureus.
Thai researchers conducted tests to evaluate the Preliminary test results of black tiger prawns’ storage in Ozone
effectiveness of ozone in destroying microorganisms in Slurry Ice (OSI) and Flake Ice (FI), the storage period of 4 days
seawater. They found that ozone-produced liquid ice (OSI) met showed that shrimp stored in Flake Ice (FI) had dark heads.
the microbial quality standards outlined in the Ministry of Public Meanwhile, shrimp stored in Ozone Slurry Ice (OSI) will be a
Health’s Announcement No. 61 (B.E. 1981) regarding “Drinking normal color. Overall, ozonized slurry ice offers a safer, more
Water in Sealed Containers.” In contrast, seawater samples efficient, and sustainable alternative for preserving seafood.
not treated with ozone did not meet the microbial quality
standards.
More Information Service Info C004
36 FOOD FOCUS THAILAND OCT 2023

22/9/2566 BE 14:36
32-36_Special Focus_Slury Ice.indd 36
32-36_Special Focus_Slury Ice.indd 36 22/9/2566 BE 14:36