Food manufacturers and consumers alike seek products with all the possible benefits and a minimum amount of drawbacks. A flavour as refreshing as its orange hue; a beverage with added nutrients without the unpleasant taste; a powdered spice that remains as fresh and fragrant as the day it was purchased—encapsulants make all this possible.
They protect ingredients and allow the delivery of active components, such as flavours and vitamins, in systems where environmental challenges exist, for example high temperatures or the presence of oxygen. Encapsulants allow manufacturers to offer their customers benefits beyond basic sustenance, developing tasty fortified and functional food and beverages that are fast becoming the norm.
The Importance Of Encapsulation
The global food encapsulation market is projected to reach US$39.5 billion by 2020 at a compound annual growth rate of 6.1 percent from 2015, with the fastest growing region being Asia Pacific, reported MarketsandMarkets in July 2015. As encapsulation allows manufacturers to overcome a wide range of technical challenges as well as achieve unique functional properties in food, it is easy to see why the encapsulation market is growing so rapidly.
As consumers become more focused on their health and the nutritional value of their food, there is pressure on the food manufacturing industry to deliver quality food and beverages with added health benefits. Enriching products with vitamins and nutrients has become a regular occurrence, but this presents a challenge for food manufacturers, who need to meet consumers’ demands for added health benefits whilst maintaining flavour and colour.
This is where encapsulated food ingredients become a vital part of food processing. As well as preservation, colour and flavour enhancement, encapsulation also offers a solution for food and beverage challenges, such as nutrient retention and overall sensory profile improvement. This is particularly relevant in cases where the flavour of a product may be altered due to a high level of nutrients being added.
Encapsulation Science 101
Encapsulation is a process that helps to protect active ingredients by embedding them in a powder and holding them in a matrix. Encapsulants offer huge application versatility which manufacturers can take advantage of, from powdered drink mixes and herb extract powders to vitamin tablets and prescription medication.
Encapsulation can prevent unwanted flavours from affecting a finished food product or provide the protective coating for a fish-oil gel that dissolves once swallowed. It can also be used to protect reactive, sensitive or volatile ingredients against extreme manufacturing or storage conditions, convert the ingredients into easier forms to handle during processing, and even modify the release and efficacy properties of active ingredients.
There are two major types of materials available to manufacturers, depending on the desired functional performance and encapsulating technique used.
The first of these materials is gum arabic, also known as acacia gum, which has traditionally been used in microencapsulation by spray drying due to its film-forming and emulsion stabilisation properties. As gum arabic is a naturally harvested product, there can be inconsistencies due to growth and harvest conditions which can affect its encapsulation performance.
The supply of gum arabic can also be impacted by extreme weather conditions and geo-political issues, which can both limit the supply and raise the costs. Consistency of quality and supply is vital for manufacturers who need to be able to supply their customers with a high standard of product on a regular basis. The uncertainty surrounding the quality and supply of gum arabic is a challenge for food manufacturers, motivating the industry to seek more reliable alternatives.
This is where the alternative material used for microencapsulation stands out. Octenylsuccinic anhydride (OSA) modified starch, the second type of material available, is typically derived from waxy maize and is widely used to replace gum arabic due to its excellent emulsification performance for encapsulating oil-based ingredients.
The manufacturing of starch follows a stringent process with tight controls, ensuring batch-to-batch consistency and quality that gives it a clear competitive edge over gum arabic. A well designed OSA-modified starch can be effective in reducing the surface tension, or interfacial tensions, to achieve a fine oil droplet size, which translates into high encapsulation and manufacturing efficiencies.
The Use Of Modified Starches In Encapsulation
Modified starches are generally used in four encapsulation processes: the spray drying of flavours and fats, spray drying natural extracts, encapsulating vitamins and other nutrients, and plating.
In all of these processes, the use of OSA starches has proved to be more efficient and reliable than the use of gum arabic. Each of these processes presents unique challenges, which has led to the development of specific encapsulating agents to overcome them.
Spray-Drying Flavours And Fats
When spray-drying flavours and fats, oil-based ingredients are extremely sensitive and difficult to handle. They are also prone to oxidation during storage if not properly encapsulated, and flavour chemicals can often be very volatile and sensitive to process stress and heat. Without proper encapsulation, these ingredients can be negatively affected and lost during the spray-drying process.
Additionally, spray-drying fats at high oil loading leads to an issue with stickiness. During processing, powder particles can stick to both each other and the walls of the dryer, causing operational difficulties and low yields. Ensuring a fine oil droplet size and high solids content in the pre-emulsion before the spray drying takes place helps to address these challenges and deliver high encapsulation and process efficiencies. In turn, these generate cost reductions and good product stability during storage.
When using gum arabic, a larger amount is needed for successful encapsulation compared to modified starch. This increases the emulsion viscosity and limits the maximum solid content within the pre-emulsion. Modern OSA starches are specifically designed for encapsulation, making them a strong replacement for the more expensive gum arabic and proteins that have traditionally been used.
Another key issue in spray drying flavours is the risk of flavour loss through evaporation. As the emulsion is atomised into the drying chamber, it comes into contact with hot air, leading to water evaporation. The flavour components may escape with the water or become lost as a result of the high temperature. As the emulsion dries, a hard crust forms on the surface of the droplet—a critical element to ensure flavour retention. The crust limits the amount of sensitive flavour components that can escape with the hot air during the early stage of drying process.
Combined with fast drying rates, greater production efficiencies can be achieved with fewer ingredient loss and lower energy cost. High solids content in the emulsion not only speeds up the drying rate but also enables the formation of a thick, dense glassy wall. This helps to reduce oxygen permeation, further increasing flavour retention.
To combat the challenges of spray-drying flavours and fats, specific OSA starches are available to produce fine emulsion droplets that are stable for up to 24 hours of storage under ambient conditions, making the starches easy to work with and offering a higher yield.
Spray-Drying Natural Extracts
Stickiness is also a common issue in spray-drying natural extracts, for example ingredients containing hydrolysed proteins, such as vegetable protein, or ingredients that are rich in sugar and acids, such as herbs and fruit juice.
Stickiness is caused by low molecular weight peptides or sugars, which have low glass transition temperature. Overcoming this challenge requires a high molecular weight polymer to be added into the emulsion. Starch has been proven to be an effective bulking agent for improving the flowability of hygroscopic products, such as soya sauce, hydrolysed proteins and natural extracts.
Formulations containing starch have also shown to improve sachet-filling operation for seasonings, and have lower moisture absorption, which reduces caking during storage.
Vitamins And Other Encapsulation Applications
Applications such as carotenoids, fatty esters and vitamins require specifically developed modified starches for encapsulation. As the delicate ingredients are prone to oxidation, high performance encapsulants are necessary to ensure that foods and beverages carrying these essential ingredients look and taste fresh throughout their shelf-life.
The right encapsulant also enables better processing efficiencies, reducing overall costs whilst also contributing to a higher quality, more shelf stable product.
High-performance encapsulants can be used in a wide range of products from bartender drink mixes to bakery mixes and supplements. Independent tests on products currently available in the market have shown that modified starch has a lower surface oil than gum arabic, gelatin and casein, providing better efficacy and longer product shelf-life.
Although plating, technically speaking, is not an encapsulation technology, it is the most economical delivery technique used in the food industry for transforming liquid ingredients into dry form. The process involves blending oil-based ingredients, such as flavour oils, with starch or maltodextrin to allow the oils to be absorbed.
Common applications for plating include seasoning powders, where manufacturers need to transform oil soluble ingredients and extracts into free-flowing powder for ease of use and handling.
Delivering Functionality And Flavour
Today’s consumers are busier and more demanding than ever. They want their food and drinks to be convenient and affordable, taste great and be packed full of health benefits. To meet these needs, manufacturers need to take advantage of innovative encapsulating agents which allow them to deliver active components, such as flavours and vitamins, in systems with environmental challenges.
Modified starches derived from natural sources, such as corn, tapioca and potato, can also offer money-saving benefits whilst allowing manufacturers to develop nutritious and easy-to-use ingredients—a combination now possible to achieve.