bottling plants [4]. The Direct Air Capture, discussed in Chap. 6 would solve this
outage issue as CO 2 would be produced when and where required [5], but such
technology at the moment has a cost not economically viable for such an application. Other initiatives such as NewCO 2 [6] try to fill the gap between available
CO 2 production sites and ad hoc demands.
8.3 Uses of CO 2 and Its Quality
Different applications demand each a specific purity of CO 2 . The CO 2 source
determines the nature of contaminants, such as nitrogen- or sulphur-oxides in flue
gases or hydrocarbons in some of the industrial streams listed in Table 8.1, which
need to be removed for most applications. Food-grade CO 2 is the one that requires
elimination of contaminants at maximum level, and this increases the cost of
production. The standards for purity are internationally defined: ISBT, CGA, EIGA
define standards for purity. Such standards tend to guarantee that from food-grade
CO 2 all possible contaminants have been removed to one part per billion (ppb) level
so that they will not influence taste or odor and will be harmless for the health of
consumers. Other non-noxious species, such as water (humidity) and oxygen, also
need to be removed to a level acceptable for the specific process in which CO 2 is
employed. Quality control and quality assurance measures currently implemented
by the producers of L-CO 2 for food utilization are very strict. Noteworthy, the
detection limit of contaminants has much improved in the last years and allows to
go down to ppb threshold.
8.3.1 Food Industry
L-CO 2 finds a large use in food industry for a variety of applications that demand
food-grade CO 2 that does not contain contaminants potentially harmful to humans.
Most common uses are additive to beverages, cooling agent during processing
and transportation, food packaging (modified atmosphere packaging-MAP),
extraction of fragrances, slaughter and stunning of pig, poultry confectioning,
supercritical extraction, decontamination of food stuff (antibacterial). As a matter
of fact, CO 2 goes across the almost entire foodstuff series of products for their
preparation, shipping, selling, and conservation. In cooling applications, with
respect to mechanical cooling, L-CO 2 saves space as the compressor is avoided.
Safety has a key role in such applications and procedures for Hazard Analysis of
Critical Control Points, or HACCP, which have been established to identify the
correct steps in the food processing chain.
In food packaging applications, CO 2 now competes with dinitrogen (N 2 ), the
choice being driven by the availability (N 2 is obtained by air-distillation and is, in
principle, continuously available) and cost (the cost of DAC, which would make
CO 2 always available, is much higher than that of N 2 production). Both gases are
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outage issue as CO 2 would be produced when and where required [5], but such
technology at the moment has a cost not economically viable for such an application. Other initiatives such as NewCO 2 [6] try to fill the gap between available
CO 2 production sites and ad hoc demands.
8.3 Uses of CO 2 and Its Quality
Different applications demand each a specific purity of CO 2 . The CO 2 source
determines the nature of contaminants, such as nitrogen- or sulphur-oxides in flue
gases or hydrocarbons in some of the industrial streams listed in Table 8.1, which
need to be removed for most applications. Food-grade CO 2 is the one that requires
elimination of contaminants at maximum level, and this increases the cost of
production. The standards for purity are internationally defined: ISBT, CGA, EIGA
define standards for purity. Such standards tend to guarantee that from food-grade
CO 2 all possible contaminants have been removed to one part per billion (ppb) level
so that they will not influence taste or odor and will be harmless for the health of
consumers. Other non-noxious species, such as water (humidity) and oxygen, also
need to be removed to a level acceptable for the specific process in which CO 2 is
employed. Quality control and quality assurance measures currently implemented
by the producers of L-CO 2 for food utilization are very strict. Noteworthy, the
detection limit of contaminants has much improved in the last years and allows to
go down to ppb threshold.
8.3.1 Food Industry
L-CO 2 finds a large use in food industry for a variety of applications that demand
food-grade CO 2 that does not contain contaminants potentially harmful to humans.
Most common uses are additive to beverages, cooling agent during processing
and transportation, food packaging (modified atmosphere packaging-MAP),
extraction of fragrances, slaughter and stunning of pig, poultry confectioning,
supercritical extraction, decontamination of food stuff (antibacterial). As a matter
of fact, CO 2 goes across the almost entire foodstuff series of products for their
preparation, shipping, selling, and conservation. In cooling applications, with
respect to mechanical cooling, L-CO 2 saves space as the compressor is avoided.
Safety has a key role in such applications and procedures for Hazard Analysis of
Critical Control Points, or HACCP, which have been established to identify the
correct steps in the food processing chain.
In food packaging applications, CO 2 now competes with dinitrogen (N 2 ), the
choice being driven by the availability (N 2 is obtained by air-distillation and is, in
principle, continuously available) and cost (the cost of DAC, which would make
CO 2 always available, is much higher than that of N 2 production). Both gases are
126
8 Use of CO 2 as Technical Fluid (Technological Uses of CO 2 )