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Causes of Aroma Loss in Beverages: Why Beverages Lose Their Aroma?

Causes of Aroma Loss in Beverages

Aroma plays a crucial role in the sensory appeal of beverages. However, during processing and storage, many drinks lose their natural fragrance due to chemical and physical changes. This article explores the primary causes of aroma loss in beverages, from oxidation and Maillard reactions to evaporation and fermentation losses.

Chemical Causes of Aroma Loss in Beverages

Chemical changes often result in permanent aroma loss or the formation of undesirable flavors.

1. Oxidation: The Primary Culprit in Aroma Degradation

What is Oxidation?

Oxidation is a chemical reaction where molecules lose electrons, typically through interaction with oxygen. In the context of beverages, oxidation primarily affects organic compounds, particularly volatile aroma compounds, leading to their degradation or transformation into new compounds. Oxidation can be triggered by factors such as heat, light, air exposure, and the presence of certain metals acting as catalysts.

How Oxidation Affects Beverage Aromas

Oxidation is one of the primary culprits behind aroma degradation in beverages, significantly altering their sensory characteristics. This chemical reaction affects volatile compounds, leading to a loss of freshness, the development of off-flavors, and an overall decline in beverage quality.

1. Degradation of Key Aroma Compounds

Many of the most desirable aromas in beverages come from volatile organic compounds like esters, aldehydes, and terpenes. These compounds are highly reactive with oxygen, which breaks them down or transforms them into less aromatic or unpleasant compounds.

2. Formation of Unwanted Byproducts (Off-Flavors)

Oxidation doesn’t just remove pleasant aromas—it also creates new, often undesirable, volatile compounds that can lead to off-flavors.

3. Diminished Overall Aroma Intensity

Oxidation leads to a general loss of volatile compounds, reducing the aroma intensity of a beverage. This is especially evident in products like fresh fruit juices, beers, and wines, where the vibrant aroma bouquet is essential to quality perception.

4. Shortened Shelf Life and Quality Deterioration

The effects of oxidation continue to progress during storage, meaning that even if a beverage starts with an excellent aroma profile, prolonged exposure to oxygen will degrade its sensory attributes over time.

Prevention Tips

To mitigate these effects, beverage producers use techniques such as:

Oxidation is an inevitable challenge in beverage production, but with proper formulation and processing strategies, its impact on aroma loss can be significantly minimized.


2. Maillard Reactions: How Heat Alters Aromas

What is the Maillard Reaction?

The Maillard reaction is a complex series of non-enzymatic browning reactions that occur between reducing sugars (such as glucose and fructose) and amino acids when exposed to heat. This reaction is responsible for the deep flavors and aromas found in baked goods, roasted coffee, and caramelized foods. However, in beverages, especially those that rely on fresh, fruity, or delicate aromatic profiles, Maillard reactions can lead to unwanted aroma alterations.

How Maillard Reactions Change Beverage Aromas

1. Formation of New Aromas (Cooked or Caramelized Notes)

During beverage processing, particularly under heat-intensive conditions such as pasteurization, drying, or concentration, Maillard reactions can produce a variety of new aromatic compounds.

While these aromas are desirable in coffee or malt-based drinks, they are typically considered defects in fruit juices, teas, and delicate floral beverages, as they interfere with the intended sensory profile.

2. Degradation of Fresh and Fruity Aromas

Maillard reactions not only generate new compounds but also degrade volatile compounds that contribute to fresh, fruity, and floral aromas.

3. Increased Perception of Bitterness and Astringency

In some beverages, Maillard-derived compounds interact with phenolic components, leading to astringency and bitterness.

4. Color Changes Indicating Aroma Degradation

Maillard reactions contribute to darkening in beverages that undergo heat treatment, often a sign of flavor alteration.

Prevention Tips

To control and minimize Maillard reaction effects in beverages, manufacturers implement several key strategies:

While the Maillard reaction plays a valuable role in flavor development for some beverages like coffee, malt drinks, and dairy-based formulations, it can be a challenge in fresh juices, teas, and light floral beverages. Managing processing conditions effectively is crucial to preserving the intended aroma profile while preventing the formation of off-notes.


3. Ester Hydrolysis: Breaking Down Fruity Aromas

What is Ester Hydrolysis?

Ester hydrolysis is a chemical reaction where esters, key contributors to fruity and floral aromas in beverages, break down into their corresponding acids and alcohols. This reaction is catalyzed by acids, bases, heat, or enzymatic activity, leading to the gradual degradation of aromatic compounds.

Beverages rich in esters, such as fruit juices, wines, and flavored drinks, are particularly vulnerable to hydrolysis, which can alter their sensory characteristics over time. The process can be exacerbated by storage conditions, pH levels, and processing methods, ultimately leading to a loss of desirable aroma compounds.

How Ester Hydrolysis Affects Beverage Aromas

1. Loss of Fruity and Floral Aromas

Esters are among the most important volatile compounds responsible for the fresh, fruity, and floral notes in beverages. Hydrolysis breaks these esters into their parent alcohols and acids, which often lack the same intense and pleasant aromatic qualities.

The result is a beverage that loses its vibrant aroma profile and may develop unwanted off-notes.

2. Increase in Acidity and Off-Flavors

Since ester hydrolysis releases organic acids, it can gradually alter the beverage’s pH and taste profile:

3. Heat and Storage-Related Aroma Degradation

The rate of ester hydrolysis increases significantly under certain conditions:

4. Enzymatic Hydrolysis in Fermented Beverages

In fermented beverages like wine, beer, and kombucha, enzymes produced by yeast and bacteria can actively hydrolyze esters post-fermentation:

Prevention Tips

To control and minimize ester hydrolysis, manufacturers implement several strategies:

Ester hydrolysis is a major factor in aroma loss, particularly in fruit juices, wines, and flavored beverages. By managing processing conditions, storage, and formulation, producers can significantly reduce its impact, preserving the fresh, fruity character of their products.


4. Thermal Decomposition of Sulfur Compounds

What is Thermal Decomposition of Sulfur Compounds?

Thermal decomposition of sulfur compounds occurs when heat causes the breakdown of volatile sulfur-containing molecules in beverages, leading to significant changes in aroma. Sulfur compounds, though often present in minute quantities, have a profound impact on the sensory profile of beverages due to their low detection thresholds.

This decomposition is particularly relevant in heat-processed beverages such as pasteurized fruit juices, thermally treated wines, and sterilized dairy drinks. The reaction is often accelerated by high temperatures, pH variations, and exposure to oxygen or catalytic metals.

How Thermal Decomposition of Sulfur Compounds Affects Beverage Aromas

1. Loss of Fresh and Desirable Sulfur-Containing Aromas

Some sulfur compounds contribute positively to a beverage’s aroma. For example:

When exposed to heat, these compounds break down into less desirable byproducts or evaporate completely, leading to a loss of their characteristic aromas​.

2. Formation of Unpleasant Off-Flavors

Thermal decomposition can lead to the formation of unpleasant, sulfurous, or burnt aromas, which negatively affect beverage quality. Some of the most common off-flavors include:

This is especially problematic in beverages that undergo high-temperature processing, as the delicate balance of volatile sulfur compounds is easily disrupted​.

3. Acceleration of Aroma Degradation Due to Heat and Oxygen

Sulfur compounds are highly reactive and prone to oxidation. In the presence of heat, oxygen, and catalytic metal ions (e.g., iron, copper), they rapidly degrade into volatile or non-volatile byproducts.

4. Impact on Beverage Stability and Shelf Life

As sulfur compounds degrade, the overall stability of a beverage is compromised.

Prevention Tips

Thermal decomposition of sulfur compounds plays a crucial role in beverage aroma loss, particularly in heat-processed products. Proper formulation and processing techniques can help preserve desirable sulfur compounds while minimizing the formation of unpleasant sulfur-related off-flavors.


Physical Causes of Aroma Loss in Beverages

Physical losses occur when volatile aroma compounds escape due to evaporation, heat, or gas movement.

1. Evaporation During Juice Concentration

What is Evaporation During Juice Concentration?

Juice concentration is a process designed to remove excess water from fruit juices to reduce storage and transportation costs while improving product stability. However, this process inherently leads to the loss of volatile aroma compounds due to evaporation.

Since fruit juices contain heat-sensitive volatiles, the concentration process is often carried out under reduced pressure, low temperatures, and short residence times in evaporators. Despite these precautions, the loss of essential aroma compounds remains a significant challenge​.

How Evaporation Affects Beverage Aromas

1. Loss of Highly Volatile Aroma Compounds

During juice concentration, volatile compounds evaporate along with water, altering the original flavor profile. The degree of aroma loss depends on the volatility of each compound:

This means that concentrated juices often have a weaker, less complex aroma compared to fresh juice.

2. Reduction in Freshness and Flavor Complexity

The removal of key volatile esters and aldehydes leads to a flattening of aroma complexity:

This degradation is particularly problematic in juices where freshness is a key quality marker, such as orange, apple, and berry juices​.

3. Concentration of Non-Volatile and Less Desirable Components

As water is removed, non-volatile compounds like sugars, acids, and some polyphenols become more concentrated. This changes the balance of flavors, often making juices taste overly sweet or acidic while lacking the bright, fresh top notes of the original juice.

4. Variability in Aroma Retention Across Different Juices

The extent of aroma loss varies significantly between different fruit juices due to differences in their volatile compositions:

Prevention Tips

To mitigate aroma loss in juice concentration, manufacturers implement several strategies:

Evaporation during juice concentration is a major factor in aroma loss, affecting the sensory quality and consumer perception of fruit juices. Advanced processing techniques and aroma recovery strategies are essential to maintaining the authentic taste and aroma of the original fruit.


2. Heat-Induced Vaporization During Pasteurization

What is Heat-Induced Vaporization During Pasteurization?

Pasteurization is a heat treatment process used to eliminate pathogens and extend the shelf life of beverages. However, during pasteurization, many volatile aroma compounds are lost due to heat-induced vaporization. This occurs because heating increases the volatility of aroma compounds, causing them to evaporate and escape from the liquid phase.

While pasteurization is essential for food safety, its impact on aroma compounds can significantly affect the sensory quality of beverages, particularly fruit juices, wines, and dairy-based drinks.

How Heat-Induced Vaporization Affects Beverage Aromas

1. Loss of Key Volatile Aroma Compounds

Many aroma compounds are inherently volatile, meaning they readily evaporate when exposed to heat. During pasteurization:

As a result, pasteurized beverages often have a less vibrant aroma compared to fresh, unprocessed counterparts.

2. Formation of Cooked or Processed Off-Flavors

In addition to losing natural aromas, pasteurization can also generate new undesirable aroma compounds through chemical reactions:

This transformation can make juices and other beverages taste less fresh and more like processed products.

3. Impact on Freshness and Flavor Complexity

The loss of delicate volatiles and the formation of new compounds result in a less complex aroma profile.

4. Pasteurization Conditions Influence Aroma Loss

The severity of aroma loss depends on factors like:

Prevention Tips

Heat-induced vaporization during pasteurization is a major challenge in beverage production, affecting both aroma intensity and complexity. By optimizing processing conditions and utilizing aroma recovery technologies, manufacturers can reduce aroma losses and preserve the natural sensory profile of their beverages.


3. Degassing in Fermentation & Carbonation

What is Degassing in Fermentation & Carbonation?

Degassing refers to the process of gas removal from a liquid, which occurs naturally during fermentation and intentionally in carbonation adjustments. In the context of beverages, degassing primarily affects aroma retention by stripping volatile compounds from the liquid phase as gas bubbles rise and escape.

How Degassing Affects Beverage Aromas

1. Loss of Key Aroma Volatiles Due to CO₂ Stripping

As CO₂ bubbles form and escape, they carry volatile aroma compounds with them, leading to a reduction in the beverage’s aromatic intensity.

This effect is particularly pronounced in beer, wine, and sparkling beverages, where excessive degassing can flatten aromatic complexity.

2. Unintended Aroma Alterations in Fermented Beverages

During fermentation, CO₂ degassing can change the balance of aroma compounds by selectively removing more volatile molecules, leading to:

3. Aroma Degradation in Carbonated Beverages

In carbonated soft drinks and beers, improper carbonation adjustments can accelerate aroma loss:

4. Sensory Impact: Reduction in Complexity and Perceived Freshness

When volatile aroma compounds are lost through degassing, beverages lose their intended complexity and depth:

Prevention Tips

Degassing is a critical factor in aroma loss, particularly in fermented and carbonated beverages. By carefully controlling CO₂ evolution and retention, manufacturers can preserve the sensory complexity of their products while minimizing unintended aroma degradation.


Final Summary: How to Preserve Beverage Aromas

Reason for Aroma Loss Description Key Affected Aroma Compounds Impact on Beverage Quality Prevention Strategies
Oxidation A chemical reaction where oxygen interacts with volatile aroma compounds, leading to degradation and formation of off-flavors. Esters, aldehydes, terpenes Loss of freshness, formation of off-flavors, shorter shelf life. Use antioxidants, minimize oxygen exposure, optimize packaging.
Maillard Reactions A heat-driven reaction between amino acids and reducing sugars that creates new aroma compounds, often leading to ‘cooked’ or caramelized notes. Furans, pyrazines, Strecker aldehydes Unintended caramelized or cooked flavors, reduction of fruity notes. Lower heat processing, optimize sugar and amino acid content.
Ester Hydrolysis The breakdown of esters into their corresponding alcohols and acids, reducing fruity and floral aroma intensity. Ethyl butanoate, isoamyl acetate, methyl anthranilate Diminished fruitiness, increased acidity, and possible off-flavors. Control pH and storage conditions, use aroma recovery techniques.
Thermal Decomposition of Sulfur Compounds The breakdown of sulfur-containing aroma compounds due to heat, leading to loss of fresh sulfur notes and formation of undesirable off-flavors. Methanethiol, dimethyl sulfide, hydrogen sulfide Rotten egg, skunky, or burnt notes; loss of fruity sulfur aromas. Reduce heat exposure, use inert gas flushing, optimize packaging.
Evaporation During Juice Concentration Loss of volatile aroma compounds during the evaporation process used to concentrate juices, affecting freshness and complexity. Ethyl pentanoate, hexanol, terpenes Duller taste, reduced aromatic complexity, loss of freshness. Use low-temperature vacuum concentration, aroma recovery methods.
Heat-Induced Vaporization During Pasteurization The volatilization of key aroma compounds due to heat exposure during pasteurization, leading to aroma loss and potential off-flavors. Limonene, ethyl butanoate, aldehydes Flattened aroma profile, potential ‘cooked’ taste, reduced complexity. Use lower temperature processing, implement aroma recovery systems.
Degassing in Fermentation & Carbonation The escape of volatile compounds along with COâ‚‚ during fermentation or carbonation adjustments, reducing aroma intensity and freshness. Esters, thiols, aldehydes Reduction in fruity, floral, and fresh aromas, leading to a flatter taste. Optimize fermentation conditions, use controlled carbonation techniques.

Aroma loss in beverages is inevitable to some extent, but by controlling temperature, oxidation, and processing techniques, we can significantly reduce unwanted changes. Whether you are a manufacturer or a home brewer, these strategies will help you retain the true essence of your favorite drinks.


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