The Production of Flavors
Flavors, produced on an industrial scale starting in the nineteenth century, are integral components of packaged foods and other consumer goods. The source can be natural, being derived from a spice, fruit, vegetable or similar, or artificially created through a series of chemical reactions.
Strong demand for convenience foods and the growing demand for natural and organic ingredients, which are widely perceived by consumers as safer as or better than artificial or synthetic ones, has generally increased the demand for flavors. In comparison to artificially derived flavors, natural flavors typically cost more and are more prone to supply interruptions due to changes in weather, disease, politics or economics.
Natural flavors have their sources in a wide variety of plants, animals, fungi and microorganisms. Flavor compounds are usually not a significant part of plants, typically comprising <1%, sometimes much less than 1%, of the plant’s total weight. The compounds are sometimes available at high purity (such as orange oil from orange peels) and at other times are only available at low concentration in the source material.
Commercial production must concentrate these compounds through processes such as distillation, CO2 extraction, low temperature vacuum distillation, solvent extraction as well as filtration. Microorganisms may also be used to produce traditional flavors compounds to ferment natural substrates to yield natural flavors compounds that were difficult to isolate from natural sources or only available via synthetic organic chemical techniques.
The processes utilized to produce the flavorings often yield high levels of solids, either from the source or due to the use of components of the process such as carbon or diatomaceous earth. The complexity of the compounds may results in formation of particles that appear as a haze that must be removed prior to packaging.
The solids may actually be soft and deformable which complicates the capture process as they can be extruded through filters. Compatibility is often an additional factor that must be considered as many of the chemicals used in the extraction are solvent based. The flavorings may also be aggressive in nature, such a terpenes derived from citrus products.
The use and selection of filtration is therefore essential to producing particle free, high quality flavors that are added to a wide variety of products such as soda, water, tea, candy and even pharmaceutical preparations.
The chemical composition of the processes often requires the use of polypropylene media. However, typical polypropylene pleated media lacks the depth to adequately capture deformable particles. Polypropylene depth filters such as the Stratum A and Stratum C on the other hand are very effective at gel capture. While providing the necessary depth, the four zone construction of the Stratum products provide a combination of best in class flow rates and consistent retention characteristics, something lacking in many melt blown products in the market.
Despite the superior flow and retention characteristics of the Stratum products, pleated products offer significantly better flow rate which can often be critical to meet sizing or process time requirements. Products such as the QXL provide both the depth and surface area advantage of pleated polypropylene cartridges by using a hybrid pleated depth construction combined with a graded pore structure to create higher surface area.
One of the limitations of microfiltration cartridges is their limited application in high solids applications, which can be present in processing flavorings. In these situations, technologies such as a plate and frame, possibly with a pre-coat of diatomaceous earth (DE) may be used, which is both cumbersome in assembly and cleaning.