What is Pasteurisation ?

• It is a food preservation technique, where food is heated to a specific temperature for a set period to eliminate harmful microorganisms and enzymes to reduce food spoilage by extending shelf life. This process denatures proteins and alters membranes¹ 
• Different food and beverages are pasteurised using various methods, depending on material and its contributory preservation factors. For example, drinks high in acidity, can determine the time and temperature used in pasteurisation - such as an orange juice which is acidic, requires high temperature ranging between 95-98 °C for 10-30 seconds. Since fruit juice has a high acidity, microorganisms cannot usually grow, therefore pasteurisation is done to inactivate unwanted enzymes from the fruit that may cause shorter shelf lives. Other factors can include storage temperature, pack atmosphere or oxygen exposure and water activity³ 
• Pasteurisation in ready-to-drink, prevents public health hazards enabling safe consumption while ensuring safety and extension of shelf life, without compromising on quality. This is also beneficial for wide distribution over long distances without the risk of spoilage and consistency in the flavour and appearance by preventing unwanted fermentation via microbial activity

 Methods of Pasteurisation

• High Temperature Short Time (HTST) Pasteurisation
  • Heat beverages to a high temperature for a short period of time, typically around 15-30 seconds, then is rapidly cooled
  • Common in fruit juices(guava),⁴ kegged beer, and dairy-based drinks
• Low Temperature Long Time (LTLT) Pasteurisation
  • Heat beverages to a lower temperature and high pressure for a longer period of time⁵
  • Used for products requiring gentler treatment to preserve flavour and nutrients, as well as, on milk products to make cheese and ice-cream
• Ultra-Pasteurisation (UHT)
  • Beverages are heated to temperatures typically above 135°C for a short period of time.
  • Common in dairy and plant-based drinks(e.g. pomegranate) ensuring prolonged shelf life for storage at room temperature without refrigeration⁵

Benefits of Pasteurisation in Ready-to-Drink Beverages

• Safety
  • Eliminates the growth of harmful bacteria such as Salmonella, Escherichia coli O157:H7, and Listeria common in beverages, thus safer for consumption
• Product Stability
  • The microbial growth is slowed down through pasteurisation resulting in a lower risk of spoilage and contamination, which is advantageous when transporting over long distances. As well as, the consistency of flavour means that the method produces uniform products, which is beneficial to industries to make them on a large scale⁶
• Quality
  • Modern pasteurisation such as High Temperature Short Time (HTST) and Ultra High Temperature (UHT), minimises impact on flavour, texture, and nutritional content of the products. And due to prolonged shelf life on pasteurised Ready-to-drink beverages, it is more convenient for consumers, without the need for refrigeration

Challenges in Pasteurising Ready-to-Drink Beverages

• Temperature Sensitivity of Ingredients
  • Some ingredients, such as vitamins, and antioxidants, may degrade when exposed to high heat. Further resulting in changes to its physical appearance including colour and texture, making it difficult to mimic natural forms of the product. For example, the colour of the milk may change to a faint yellow
• Balancing Safety and Quality
  • Over-pasteurisation can make it challenging to maintain the correct balance and natural properties of the product by affecting taste, aroma, and texture
• Presence of Heavy materials
  • Heavy metals are naturally occurring elements with high atomic numbers and mostly found in the Earth’s crust. Heavy metals cannot be easily degraded and can be classified as essential and non-essential. Certain metals, such as Cu, Fe, and Mn, are vital for human beings for development and respiration. However, when the concentration of the heavy metals ingested surpassing the limit, it can be hazardous⁷
  • Heavy metal contamination in beverages is frequently the result of environmental and industrial contamination, usually by equipment for fermentation, conditioning, filtration, carbonation, and packing. Additionally, the utensils, water and raw materials used are also sources of metal contamination. The sources of heavy metals contamination in beverages are called exogenous (heavy metals from added chemicals during production and contamination through industrial equipment used for fermentation, filtration, carbonation, and packaging) and endogenous sources are natural components including water, yeast and raw materials used during the manufacturing process
  • Other chemical risks in RTD beverages include Mycotoxins (are secondary metabolites of filamentous fungi, such as Aspergillus producing severe toxic effects such as carcinogenic, hepatotoxic and genotoxic), Biogenic amines (BA (are nitrogen-containing compounds formed due to the presence of proteins and free amino acids that represent the substrates for microbial or natural enzymes with decarboxylation and amination activity. Microorganisms such as Salmonella, Escherichia and Clostridium perfringens are reported as BA sources. And high BA contents can cause food poisoning, hypertension and vasoactive and psychoactive effects) and pesticides (the most common pesticides found in wine include azoxystrobin, boscalid, cyprodinil, dimethomorph, fenhexamid, fludioxonil, and metalaxyl. During winemaking, pesticide residues are transferred from the grape skin into the wine, posing a toxicological risk to the consumer. In addition, red wine elevates the pesticide levels due to prolonged maceration (involving grape skin)
• Detection of microplastics
  • Microplastics have become another environmental pollution factor. It is especially used for packaging of ready-to-drink beverages and is beneficial for products requiring a long term storage
  • Assessing the microplastic contents in food and drinks is essential to determine how microplastics are affecting various forms including human beings and plants, their long-term implications and to implement reduction or elimination actions
• Cost and Energy Consumption
  • High energy demands of pasteurisation processes can increase operational costs for manufacturers

Alternatives to Pasteurisation

• Cold Pressing
  • A method used in juicing with the use of higher pressure than heat. This method retains higher concentrations of vitamins, minerals, enzymes and antioxidants, without the need to add sugars, preservatives and artificial ingredients⁸
• Ultraviolet- C(UV-C) Light Treatment
  • Is a non-thermal disinfection technology where short wave UV-C inactivates microorganisms (DNA modification) from the surface of the products and water – enhancing food safety and quality by not altering the sensory attributes and the nutritional values of the beverages. It also extends the shelf-life; however, handlers can potentially be exposed to harmful effects of the UVC light on their skin or eye^9,10
• High Pressure Processing (HPP)
  • Is a non-thermal preservation using high isostatic pressure transmitted by cold water to inactivate microorganisms to increase shelf-life while maintaining the organoleptic and nutritional attributes of the products¹¹  

 Consumer Perception of Pasteurisation

• Health and Safety Concerns
  • A research conducted on an outbreak of Shiga toxin-producing Escherichia coli (STEC) 0157:H7 linked to a milk pasteurisation failure at a dairy farm in England suggested that “pasteurised milk is marketed as 'safe to drink' and sold to a larger, and more dispersed, population”.¹² Thus, consumers expect pasteurisation to make beverages safe by eliminating harmful microorganisms
• Demand for Natural Products
  • With an increase in health awareness, consumers are preferring natural drink products with a focus on sustainability. According to the UK Food and Drink Federation (FDF), the “British market for organic food and drinks showed consistent growth and is expected to continue growing… Rising consumer awareness and growing demand for natural and healthier food and drink products are major drivers. People are now actively trying to lead an environmentally friendly lifestyle.”¹³
• Awareness and Education
  • It is essential to increase consumer understanding of pasteurisation in beverages for safety and quality purposes. However, this is not applicable to all RTD products as a survey conducted by action on sugar in 2020 implied Nearly 50% of respondents are not aware of the sugar content in their alcoholic drinks with 76.4% wanting nutrition information to be displayed on the bottle¹⁴

 Summary

• Pasteurisation is vital in ready-to-drink beverages to ensure safety and quality. As technology evolves. New methods of pasteurisation may allow the process to be more energy efficient while still preserving its nutritional values and taste. Ultimately, pasteurisation will continue to be a popular method in the drink industries ensuring safe consumption of beverages while meeting the quality and convenience.