mobile-logo

To satisfy different product needs, including extending shelf-life, optimizing flavor, improving texture and packaging needs, there are many new developing technologies in the beverage industry. So, beverages were processed with three different thermal processing methods, being: autoclave, retort and direct steam injection (DSI) to compare to identify which processing method is most suited to preserving the desired sensory and physicochemical attributes of the product. This study supports advancements in beverage product development particularly for flavored dairy-based beverages and nutritional dairy-based beverages.

Evaluating Thermal Processing Techniques for Vanilla-Flavored Milk Protein Beverages: UHT-DSI vs Retort vs Autoclave

Recent Technology , Oct 04, 2025

Share
Mail-bulk Linkedin X-twitter

To satisfy different product needs, including extending shelf-life, optimizing flavor, improving texture and packaging needs, there are many new developing technologies in the beverage industry. So, beverages were processed with three different thermal processing methods, being: autoclave, retort and direct steam injection (DSI) to compare to identify which processing method is most suited to preserving the desired sensory and physicochemical attributes of the product. This study supports advancements in beverage product development particularly for flavored dairy-based beverages and nutritional dairy-based beverages.

What is the purpose of thermal processing of protein beverages?

The heat treatments were performed for two main purposes being:

  • to obtain commercial sterilization,
  • to determine the quality of the product because of treatment.

High heat is needed to destroy all harmful bacteria and increase the shelf life of the beverage, and to be sold as a shelf-stable product. Although, the high protein beverages are high sensitivity foods, thus the main research focus was to determine how the three methods autoclave (UHT), retort, and autoclave impacted the stability of the beverage’s protein (preventing clumping or sedimentation) and flavor. These insights directly impact dairy beverage development and inform better beverage formulation for thermal processing techniques. [1] [2]

Types of Thermal Processing

  1. UHT-DSI- The ultra-high temperature-direct steam injection (UHT-DSI) method entails rapidly injecting steam into a liquid and heating to around 140 °C in about 3 seconds. This process minimizes heat degradation and produces a liquid for sterilization that is done as quickly as practical.

STEPS

DESCRIPTION

Preheating

90 °C – An increase in temperature occurred prior to sterilization stage.

 

Sterilization

Sterilization through direct injection of steam into product.

 

 

Rapid cooling

Cooling through vacuum chamber. The steam quickly flashes off and simultaneously cools the product;character after steam evacuation & cooling.

 

 

Homogenization

87 °C – Disruption of protein aggregates for improved stability and textural characteristics.

 

Final cooling/collection

20 °C – Cooled for packaging and collected after sterilization in a HEPA-filtered hood.

Final Storage

4          °C – Bottled and then cooled in ice bath

  1. Retort processing – Retort processing entails putting the sealed, packaged food inside a sizable, pressurised vessel (a retort) and heating it to high temperatures (for example, 123 °C for several minutes).
STEPS DESCRIPTION
Packaging Filled into 400-mL retort glass bottles.
  Processing Processed in an Allpax Multimode Retort using full immersion with recirculated water.
Conditioning 123∘C for a time equivalent to 5 min of sterilization
  Instrumentation One bottle contained a temperature probe to accurately monitor the heat penetration and ensure the target sterilization time was achieved inside the product.
  Storage 12 bottles were collected, cooled in an ice bath to ∼4∘C, and stored at 4∘C.
 
  1. Autoclave – The term “autoclave” refers to a pressurised vessel that sterilises materials using steam at high pressure (e.g., 112 °C for 6 minutes), which works similarly to a retort in food processing for in-container batch sterilisation. [3]
STEPS DESCRIPTION
Packaging Filled into 500-mL screw-cap glass bottles
Processing Processed in a Consolidated Sterilizer Autoclave.
Conditioning 112∘C for 6 min.
Storage Cooled in an ice bath to ∼4∘C immediately after processing and stored at 4∘C.

Key Findings

 

PROPERTY

 

CONTROL

 

UHT-DSI

RETORT / AUTOCLAVE

 

Protein Integrity

 

No damage

 

Moderate damage

Significant Heat Damage

Colour

Normal

Intense yellow

Intense Yellow

 

Flavour

 

Vanilla

 

Sulfur Egg (Off flavour)

Caramelized (Cooked flavour)

 

Chemical Volatile

 

Low

 

High Hydrogen sulphide and methanethiol

 

High aldehydes, esters, ketones, furans

What is the mechanism involved?

The extreme heat caused the large milk proteins to break down into smaller nitrogen-containing molecules (peptides or amino acids), which represents a significant heat alteration to the protein structure and is now less functional or potentially aggregate.

  1. UHT-DSI (140∘C for 2.3 s): A quick intense heat processed acted upon specific sulfur amino acids of the protein (ex: cysteine) that broke down to release volatile sulfur compounds (hydrogen sulfide and methanethiol) causing unacceptable sulfur-eggy off-flavor.
  2. Retort and Autoclave: A longer duration of heat, but at lower temperature favored two critical reactions:
  3. Maillard Reaction: A reaction between amino acids and residual sugars (even low levels), which forms new caramelized cooked flavors.
  4. Strecker Degradation: Further breakdown of amino acids to generate multiple aldehydes, alcohols, esters, ketones, and furans that generated palatable caramel flavor. [4] [5]
Thermal Processing Techniques for Vanilla Milk Protein Drinks

Market Items Processing Methods (UHT-DSI, Retort, Autoclave)

  1. Amul: A well-known dairy cooperative that sells UHT milk products (ex., Amul Taaza, Amul Gold).
  2. Nestlé: UHT milk products under a variety of brands.
  3. Tasty Bite: Offers ready-to-eat meals like rice, dal, and curries, utilizing retort packaging.
  4. Creamy Foods Ltd.: Their UHT milk plant utilizes DSI technology for efficient heating.
  5. Floeter India: Supplies retort pouches applicable for ready-to-eat meals and various other food products.
  6. Verka: Provides UHT milk variants such as Fresh+, Standard, Toned, and Double Toned.

Product example

Brand name: Ensure®

Product Type: High Protein Milk Chocolate Nutrition Shake

ensure-high

Source: Ensure® High Protein Milk Chocolate Nutrition Shake

What are the practical implications for product Developers?

The flavour profile desired will influence treatment selection.  A retort and autoclave, promote Maillard reactions that lead to caramelised/browned flavours, which may be favourable or unfavourable based on the product design.  Direct steam injection (DSI-UHT) methods may produce sulphurous or “eggy” notes – both are often undesirable by consumers.

If retort/autoclave processing is necessary to achieve shelf stability, developers should consider how to limit excessive Maillard browning by reducing sugar, adjusting pH and buffering capacity, or incorporating processing aids and antioxidants properly.  Conversely, the effort should be placed on reducing sulphur volatiles in DSI-UHT applications by ingredient selection, pre-treatment, or post processing aroma management. [6]

Conclusion

Thermal heat processing remains fundamental for producing safe, shelf-stable nutritional dairy-based beverages and flavored dairy-based beverages. Techniques such as UHT, retort/autoclave, and DSI afford producers options tailored to dairy beverage development needs and beverage formulation for thermal processing. Science continues to refine these methods, enabling safer, longer-lasting products with better flavour, texture, and nutrition. For expert guidance on choosing and optimizing thermal processing solutions, please reach out to our team.

Food Research Circle Logo
Let’s create something Innovative and Delicious together

Food Research Lab strives for excellence in new Food, Beverage and Nutraceutical Product Research and Development by offering cutting edge scientific analysis and expertise.

New Product Concepts

New Product Concepts
Sample Request

Sample Request
Quote Request

Quote Request
Connect An Expert

Connect an Expert
whatsapp