The aroma active ingredients typically found in beverages and liquid foods are a variety of organic compounds present in low concentrations. Classes of organic compounds which can be regarded as aromas are for instance alcohols, aldehydes, esters, lactones, carboxylic acids, hydrocarbons, phenols, ethers and terpenes. These aroma components may be altered to a large extent during the processing of beverages or liquid foods. This is mainly due to chemical reactions changing the aromaticity or occurring a physical loss. Chemical changes in aroma compounds may be due to heat induced oxidations or Maillard reactions. The result may be the disappearance of the original aroma compounds or the formation of a new aroma compound from the original aroma. Physical changes in the aroma composition can also occur during concentration and removal of the excess water, while some amounts of the volatile aroma compounds like esters might be lost due to evaporation. Changes in aroma composition are unnecessary in many cases, and in order to minimize or avoid such changes and losses, aroma recovery techniques can be employed. Alfa Chemistry is passionate about exploring aroma recovery technologies to ensure that natural flavors and active ingredients are protected while high-quality products are produced.

Classification

Aroma recovery technologies can be broadly classified into the following three categories.

• Aroma recovery through distillation

Aroma compounds are usually volatile to some extent in order to allow for an olfactory experience. Therefore, the use of volatility-based techniques such as distillation to recover the aroma seems to be the most fundamental.

• Aroma recovery through pervaporation

Pervaporation is an attractive technology for processing thermal sensitive aroma compounds. In this technique, aroma compounds are separated from the gaseous mixture thanks to their more favorable penetration through the membrane. They are then continuously condensed on the other side of the membrane, generally in liquid form.

• Aroma recovery through supercritical fluid extraction

Supercritical fluid extraction is a process which uses substances at pressure and temperature above the critical point as solvents to extract valuable materials. In the last decades of the 20th century, aroma extraction with supercritical carbon dioxide as solvents was widely used in the food industry.

Applications

Aroma recovery technology has a potential in some commercial applications. These applications mainly involve the recovery of aromas from fruit juices, waste and by-products. Details are described below.

• Recovery of fruit juice aroma

During the thermal processing of fruit juices, many aroma components are lost due to their high volatility in aqueous solutions. These compounds are quite important for the sensorial quality of the juice and must therefore be recovered. The main solution is by recovering and capturing the flavor volatiles prior to processing and then re-adding them to the final product.

• Recovery of waste or by-product aroma

Discarded waste or by-products (such as fruit peel and pulps) often include potentially valuable aroma compounds. Typically, these compounds can be recovered