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Figure 16. Microphotograph of W/O/W multiple emulsion (Courtesy of Nakashima and ShimizulS)

Recently, O/W/O emulsion technology has been utilized for producing margarine (55,56). In this case, for example, the oil phase contains lecithin and a sorbitan

Figure 17. Microphotograph of calcium alginate microspheres prepared by using W/O/W multiple emulsion (Courtesy of Nakashima and ShimizulS)

fatty acid ester, while the water phase contains skim milk powder, sugar fatty acid ester and sodium hexameta phosphate. This margarine has many characteristics: 1) soft, creamy taste and flavor, 2) water separation from margarine does not occur during whipping, 3) finished cream has resistance to deterioration and mold, 4) cream has an excellent freezing and thawing tolerance, and 5) texture of the cream is maintained well without drying and cracking.

Another O/W/O emulsion (55,56) containing monoglyceride and beta-carotene in oil phase but containing sugar fatty acid ester, whole milk powder, glucose, corn syrup and fresh cream in the water phase produced a new type of cream having additional following characteristics: 1) less oily than ordinary cream, 2) having light mouth feel and good mouth melt properties, 3) tasting similar to a fresh cream, and 4) Freeze-thaw stable like an ordinary butter cream.

3.3.4. Dissolution of Ozone Gas in Liquid (Ozonation of Liquids)

Ozone's well-known properties as an oxidant, bleach and sanitizer make it an excellent water purification and food treatment agent. Ozone is emerging as the more attractive alternative for water and waste water sanitation. The ozonated water is applicable to sterilize vegetable, fish, meat, oyster, raw materials of various foods, and food containers. However, ozonated water having high concentrations of ozone that serves as an effective sanitizer has been difficult to obtain using many conventional techniques.

Asahi Glass Inc. used SPG membranes to obtain a higher concentration of dissolved ozone (55). Producing ozonated water requires that the ozone gas be effectively dissolved and concentrated in water. By virtue of its small pore size and narrow pore size distribution, SPG membranes produce a large number of small and homogeneous bubbles in water.

In practice, water is flowing inside the microporous glass tube and ozone gas (2% in O2) is pressurized into water from outside of the tube, principle of which is similar to that used in producing emulsions shown in Figure 3. When the ozone gas passes through the pores of the microporous glass, many small ozone bubbles are formed, raising the ozone concentration in water. Asahi Glass Inc. reported that ozone concentration of 10-12 mg/1 can be obtained by pressuring ozone gas at 0.8 kg/cm2 into a 500 liter flowing water (1001/min) through microporous glass (pore diameter of 3 nm) for 80 min (Figure 18).

With recycling, ozone concentration in water could be reached up to 50 mg/1. The half-life period of ozone water thus produced was ca. 100 min. Many ozone gas bubbles dispersed in water may act as a reservior of ozone gas to attain the long half-lifeperiod.

3.3.5,Use of SPG in Processing of Food Emulsions

Since the SPG membrane emulsification method was presented, many applications of this new technique have been developed in the various industrial fields. The ultra-low fat spread (margarine), developed by Morinaga Milk Co. Ltd. in 1993, is the only industrial commodity prepared using the SPG membrane emulsification method (56,57,58). They prepared highly stable monodispersed O/W emulsions by pressing water into the oil phase through the pores of SPG

02 feeding (l/min)

water

distilled water tap water

distilled water tap water

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