4206 Fundamentals of Food Science

How it Works

The HPP method does not use heat to produce a pasteurization effect, but instead, its non-thermal property is adequately effective to inactivate both harmful and spoilage microorganisms (Muntean et al., 2016). The HPP process relies on a high water activity that makes it a preferable process for use with smoothies, fruits, and juices. The process does not heat up products, and in the case of these fruits and their associated products, the taste and appearance are unchanged. The process is suitable when preparing DETOX products and antioxidants. It is carried out when products are in their packaging materials. Therefore, it eliminates chances of contamination at the moment of processing and after processing. The products are either manually or by use of a machine put in a basket, and subsequently automatically channeled to the HP vessel for processing. Pressure in the HP vessel is increased to 6000 bars and exerted on the product for around three minutes, after which is the pressure is released and the water that has accumulated in the vessel is drained. The vessel bounces back to its initial state and ready for the next cycle. When loaded, the pressure vessel is usually degassed so that no microorganism is able to survive. The air is automatically removed through a deaeration valve using a low pressure fast-fill-and-drain pump (Mertens, 1995). However, there is need to balance the temperature and the pressure because an increase in pressure is deemed to be result in an equivocal increase in temperature (Butz & Tauscher, 2002). Talks of 400 to 600 Mpa in combination with a temperature <45 degrees Celsius.

Despite the fact that the principle of HPP has been known for more than 700 years, it is only in the last 20 years that it received considerable attention leading to large scale applications. The pressure is isostatic kind of pressure because it is applied simultaneously in a uniform manner in the basket holding the food products. The uniform distribution of the pressure ensures that there is no breakage or destruction of products. It is applied in a batch or in a semi-continuous process

Advantages of the HPP technique-Overview

The HPP process is able to destroy microorganisms in food without destroying essential nutrients in the food, for example, the vitamins. Also, the flavoring and color pigments are preserved. The process is designed to ensure that high hygienic protocols are followed during the final packaging stage. The product to be packaged is compressed by around 15% and subjected to a pressure of 6000 bars. The packaging material is also exposed to a similar kind of pressure, which calls for the use of flexible packaging materials, for example PE, PET, and EVON. In view of the fact that this process does not involve the addition of some chemical forms of preservatives, foods can maintain their natural and biological states (Uhde High Pressure Technologies GmbH, 2016).

Disadvantages of the HPP technique-Overview

HPP does not destroy all microbial organisms, especially the spore-forming microbes because pressure is not able to destroy the spores. Thereby, an additional antibacterial treatment is needed for reducing the spore-forming microbes. Such intense pasteurization is bound to cause to the elements that had not been affected by the pressure, and the result is a product whose organoleptic properties have been lost. The HPP process is applicable to only those food products with a high water activity.

Advantages to the Food Smoothie

Even though there is an increment of temperature through adiabatic heating, this can be modified to suit the chemical composition of the target food (Muntean et al., 2016). In view of the fact that increment in temperature is especially higher for foods with a high content of fat, the increment is not likely for the food smoothie because of the low fat content that is mainly derived from the insect protein ingredient. In comparison to thermal processing, HPP has minimal effects on low-molecular weight products, for example, vitamins, pigments, and flavor compounds. As a result, HPP is the ideal preservation method that eliminates harmful and spoilage bacteria while retaining the nutritional value and quality of the smoothie.

The packaging material for these smoothies would be made from plastic, which is considered to be adequately resilient. Again, due to the low fat content, the temperature would not be so high as to affect the plastic. A fruit product going by the name guacamole shows success despite the fact that it uses avocado, which has a high fat content (“HPP application,” n. d.). The decision to choose the HPP process should be governed by the ultimate goal of the pasteurization technique. The main limitation of the HPP is an advantage for the manufacturer because the fruit smoothies have a high content of water.

Disadvantages of HPP when Preparing the Fruit Smoothie

Gelatinization occurs when carbohydrates are subjected to high pressures as opposed to high temperatures. Also, high temperatures that result when pressure is increased in high-fat foods results in the denaturation of proteins. There are limited indications that HPP can be used on fruit smoothies hence, this is a risk that the manufacturer would be ready to take. Also, there are very high installation costs involved; therefore, it is imperative for the manufacturer to critically review the benefits of the new technology (HPP) in comparison to what he has already (HTST). The main limitation is the fact that the process is not effective on spore-forming bacteria; however, this can be addressed by using the right combinations of holding time, temperature, and pressure applied.

Recommended Changes

The ideal food that should be subjected to HPP should not have the potential to release gas, high in moisture, and not capable of producing air spaced in the packaging material. The manufacturer will require a pressure vessel, the fluid to transmit the pressure, a basket that is able to withstand the pressure, and supporting units as shown in the figure below (Heremans, 2003; Naik, Sharma, Rajput, & Manju, 2013). Recommended fluids to transmit pressure are silicone oil, castor oil, water, ethanol solutions, food-grade glycol-water solutions, and sodium benzoate (Balasubramaniam & Farkas, 2008). The high temp short time process is deemed to be an ideal strategy that ensures food safety, but preservation of low molecular weight elements of food is yet to be deciphered. Therefore, in reference to the existing HTST technique, I would recommend that the manufacturer installs the HPP while not doing without the HTST. However, the combination of the two would only take place if the raw ingredients are suspected of contamination with bacteria that cannot be eliminated using the HPP process alone like in the case of insect-based high-protein smoothies. Otherwise, in reference to the food matrix and chemical composition of the smoothie, the HPP should remain the salient pasteurization technique.

Figure showing the fundamental components that the manufacturer should consider installing (Naik et al., 2013)

Summary

In view of the properties of HPP tat render it an effective pasteurization method that preserves the organoleptic properties and quality of a product. However, after a thorough consideration of its advantages and disadvantages from a larger perspective and in relation to the fruit smoothie, I would recommend the food manufacturer to use it for his production of fruit smoothies. Despite the fact that there are shortcomings with using this method on the fruit smoothie because it may not destroy all the bacteria, the fact that the nutritive value of a fruit smoothie is more important renders it the best possible pasteurization process. The manufacturer can study the food matrix for his smoothie so as to develop the best combinations for pressure and exposure time, which is responsible for temperature increase. The manufacturer should ensure that the ingredients are produced using hygienic practices to eliminate the spore-forming bacteria and viruses that might jeopardize the safety of the food. Otherwise, in view of enzyme activity, the manufacturer should use a short shelf life to promote the use of the product at its best quality.

References

Balasubramaniam, V. M., & Farkas, D. (2008). High pressure processing. Food science and technology, 14(5), 413-418.

Butz, P., & Tauscher, B. (2002). Emerging technologies: Chemical aspects. Food Research International, 35, 279-284.

Composition of foods integrated dataset (CoFID). (n. d.). Retrieved from https://www.gov.uk/government/publications/composition-of-foods-integrated-dataset- cofid.

Heremans, K. (2013). The effect of high pressure on biomaterials. In M. E. Hendrickx, & D. Knorr (Eds.). Ultra high pressure treatment of foods (pp. 23-52). New York: Plenum Publishers,

HPP application-fruit and vegetable products. (n. d.). Retrieved from https://www.afbini.gov.uk/articles/hpp-application-fruit-and-vegetable-products.

Hugas, M., Garriga, M., & Monfort, J. M. (2002). New mild technologies in meat processing: High pressure as a model technology. Meat Science, 62, 359-371.

Muntean, M., Marian, O., Barbieru, V., Cátunescu, G. M., Ranta, O., Drocas, I., & Terhes, S. (2016). High pressure processing in food industry- Characteristics and applications. Agriculture and Agricultural Science Procedia, 10, 377-383.

Naik, L., Sharma, R., Rajput, Y. S., & Manju, G. (2013). Application of HPP for dairy preservation-future perspective. J Anim Prod Adv, 3(8), 232-241.

Parekh, S. L., Aparnathi, K. D., & Sreeja, V. (2017). High pressure processing: A potential technology for processing and preservation of dairy foods. International Journal of Current Microbiology, 6(12), 3526-3535.

Uhde High Pressure Technologies GmbH. (2016, June 24). High pressure processing (HPP) – Food preservation 2.0. New Food Magazine. Retrieved from https://www.newfoodmagazine.com/news/25329/high-pressure-processing-hpp-food- preservation-2-0/.