Iodine Sanitizers. The most effective iodine-containing compounds used in the food processing industry are iodophors. Iodine sanitizers are effective against most microorganisms, including bacteria, yeasts, and molds at a usage level of 12.5 to 25 ppm. Unlike chlorine, iodophors are effective under a wide pH range (pH 2 to 10); however, they are primarily utilized under low-pH conditions (in the acidic range). Remaining soil on surfaces will quickly bind chlorine, making it ineffective. Therefore, iodine sanitizers are more stable where there is residual soil in the environment.
The advantages to iodine sanitizers are that they can be used at much lower pH levels and that they are less corrosive than chlorine. The efficacy of iodine sanitizers is temperature dependent, however. At high temperatures (above 80 degrees Celsius), iodine becomes very corrosive. At temperatures below 50 degrees Celsius, it is unstable and ineffective.
The disadvantage to iodine sanitizers—and it is a big one—is that iodine sanitizers are two to four times more costly than chlorine sanitizers, depending on the formulation. Another drawback is that the significant contact or residence time required for an effective microbial kill is longer (up to 30 minutes). In addition, iodine sanitizers have an odor that some people find unacceptable, and iodine solutions can stain, leaving equipment surfaces yellow or orange.
QUATS. The QUATS family of tertiary amines is identified in part by its different chemical side groups. A variety of QUATS are available for use in the food processing industry, but bromine or chloride types are the most commonly utilized. QUATS readily adhere to the surface of microorganisms and are considered to be the most efficient and effective sanitizers used in the food industry. They are very effective in killing bacteria over a wide pH range (pH 6 to 10) and under high temperatures, at a usage level of 150 to 200 ppm.
One advantage to using QUATS is that they are odorless, unlike chlorine and iodine sanitizers. Also unlike chlorine and iodine sanitizers under similar pH conditions, they are noncorrosive. Disadvantages with QUATS are they are sensitive to hard water conditions, they have poor efficacy at low temperatures, and they are ineffective against spores and may support the growth of pseudomonas (spoilage bacteria). QUATS generally are two to four times more expensive than chlorine disinfectants.
Peroxide. Peroxyacetic acid (PAA) has become a popular sanitizer in the food industry. This sanitizer has an effective usage level between 100 to 250 ppm. Advantages are that this sanitizer generates little foam and is effective against a broad microbial spectrum, including bacteria, yeasts, and molds. In addition, PAA is fast-acting and pH tolerant. It is also effective over a wide range of temperatures and under hard water conditions, as well as being nonreactive with organic soils such as
fats and proteins. It is environmentally friendly and breaks down into acetic acid (vinegar), oxygen, and water. The disadvantages are that PAA does have a strong odor and becomes ineffective above pH 8.0. PAA is three to five times more expensive than chlorine.
Which Disinfectant to Use
The Code of Federal Regulations (CFR) contains requirements for sanitizing different kinds of operations. For example, 21 CFR 129.80 (d) includes a number of sanitizer options for sanitizing bottled water operations. These are all disinfectants and meet sanitizing requirements. Many times the selection of a specific sanitizer is determined by water chemistry, costs, and operational activities. If steam is available, it is a very effective and low-cost sanitizer; when steam is not available because of equipment complexity or facility limitations, many other chemical alternatives exists.
The chemical alternative is generally selected to minimize the impact on product quality. For example, a bottled water plant one will typical use a 0.1 ppm ozonated water over a 50 ppm chlorine solution because the residue from a chlorine solution may impart an objectionable taste even at levels as low as 1 ppm. Some facilities find that alternating between two different disinfectant types (such as a chlorine and a QUATS) allows better control of spoilage organisms.