Iso-Mix System Ensures Organic Wine Stability

Iso-Mix system ensures organic wine stability

The wine industry is evolving, with consumer demand for organic wine on the rise. Many wine producers are shifting focus to meet demand and looking for solutions to help them adapt production while ensuring quality, shelf life and profitability — without the use of chemical additives.

Challenges ahead as production declines then recovers

Global wine production hit an all-time low in 2017, decreasing by 8.2%. The top wine-producing countries saw declines: production dipped 4% in Italy, the world’s number one producer; 18% in France, number two in the world; and 21% in Spain, number three in the world. Both production and consumption stagnated in the US, the world’s fourth largest wine producer and largest wine consumer.

Although production levels bounced back to a record high in 2018, uncertainty remains due to various factors. These include maturing markets in Western countries, competition from other alcoholic beverages, extreme weather events, and growing consumer awareness of the health benefits from reduced alcohol consumption and all-natural food and beverages with minimal to no chemical additives.

Organic wine: A bright spot in a somewhat volatile market

Against this backdrop, there is one wine category that is booming: organic wine. Although organic wine represents a relatively small portion of worldwide wine production (3.6% in 2017), it is expanding rapidly and warmly embraced by health-conscious consumers.

The top three wine producers represent nearly 80% of the world’s organic wine production. But Italy, France and Spain are not alone; organic wine is also experiencing strong double-digit growth in most wine-producing countries.

In the past five years, organic wine production and sales have taken off. Between 2012 and 2017, production volumes doubled, and the number of new vineyards applying for organic certification is growing.

In France, certified organic vineyards accounted for about 10% of all wine producers in 2018. Forecasts indicate the number of certified organic wine growers in New Zealand will reach 20% by the end of 2020. In the U.S., organic wine is still a niche product representing only 2% of the domestic market value; however, over the past five years, local production has grown at an annual rate of 10%.

Organic wines have been around for nearly 30 years. EU regulations for organic wine-grape growing and winemaking have been in place since 1991. These include restrictions or bans on certain additives, including the total sulphite level used to ensure the stability in the final product. Similar requirements for organic wine certification exist in the U.S.

Preserving organic wines

Sulphites are chemical compounds used to preserve wine as well as other food and beverages. In the wine-making process, sulphites inhibit unwanted microbial growth both during and after grape juice fermentation; they also slow the chemical reactions, which change the quality of wine during storage.

The empirical use of sulphur during wine barrel cleaning goes back to ancient times and, since the early 1900s, has been replaced by the controlled addition of sulphites. This enabled the preservation of wine during the years-long ageing process without altering its composition. 

The term ‘sulphites’ includes sulphur dioxide or SO2, which may naturally be present in grape juice or produced by some strains of yeasts used for fermentation. The addition of extra sulphites takes place either immediately before or at the end of fermentation in order to adjust the final SO2 target.

Sulphite adjustment is based on the type of wine and/or local regulations and varies between 30 and 350 mg/l. Increasingly, consumers regard the addition of sulphites as unnatural; sulphites are considered to be an allergen and a safety concern. 

However, reducing or even eliminating sulphite addition presents new challenges to organic wine producers, who must then come up with alternative ways to ensure product stability and quality. Organic wine producers must therefore consider how best to prevent microbial contamination and chemical alterations of the wine.

Prevention of microbial contamination 

The growth of unwanted microorganisms, including bacteria, yeasts and moulds, can alter wine during the fermentation phase or during storage. Ensuring that “bad germs” are not present in the fermentation tanks from the start is a sound measure to prevent microbial growth.

This may seem obvious. However, while strict hygiene of tanks and other process components is standard practice for most processed food applications, the wine industry has traditionally relied on alcohol content (and sulphites) to guarantee the lack of pathogens.

Improperly cleaned tanks used for wine fermentation and storage may therefore contain alcohol-tolerant spoilage microorganisms that remain in the tank from one batch to the next. 

Another way to block the growth of unwanted flora is to ensure the rapid start of alcoholic fermentation, after the addition of grape juice, throughout the entire tank.

However, the larger the fermentation tank, the more challenging it is to disperse and maintain the yeast culture in a homogeneous suspension to promote rapid growth.

Modern fermentation and storage wine tanks in the biggest wine-producing facilities can be 800 cubic metres (210,000 gallons) or larger in size. Deficient mixing in such large tanks results in yeast sedimentation and wide variations in fermentation speed between the top and bottom of the tank. 

Finally, to inhibit the growth of microorganisms, organic wine producers are authorized to use certain ingredients, such as lysozyme, protective cultures or tartaric acid, as sulphite alternatives. Here again, fast and homogeneous dispersion of these ingredients is key to blocking the appearance and growth of unwanted flora.

Prevention of chemical alterations

Besides their inhibitory effect on microorganisms, sulphites are also used to protect wine against oxidation after fermentation and during storage. Oxygen is necessary at the beginning of fermentation to boost the growth of yeast cells.

Aeration of fresh grape juice by agitation or the injection of air is therefore essential for this purpose. Oxygen consumption then takes place during alcoholic fermentation. 

As oxygen from the air enters tanks after fermentation, oxidation alters the colour, taste and aroma of the wine. This problem, well known by wine producers, is made more acute through the reduction or complete suppression of added sulphites.

This means that residual dissolved oxygen must be removed as quickly as possible after fermentation – and prior to storage and bottling – to maintain the quality of the wine. 

To help remove dissolved oxygen, the wine industry injects nitrogen into the wine. Known as sparging, the injection of gaseous nitrogen displaces the oxygen in the wine and creates a protective layer of inert gas at the surface of the tank.

However, once again, the efficient and homogeneous injection of small gaseous bubbles throughout the entire volume of a large tank presents challenges.

Iso-Mix system revolutionises the wine fermentation industry

With its patented Iso-Mix system, Alfa Laval has revolutionised the fermentation industry. This straightforward versatile technology enables the introduction of liquid, gaseous and powdered ingredients into tanks of all sizes – ensuring fast, safe and homogeneous mixing. 

The core component of the Iso-Mix system is the Alfa Laval Rotary Jet Mixer, which is connected to a circulation pump by a loop equipped with injection systems for liquids and gas.

Depending on the tank size and configuration, the Rotary Jet Mixer can be top- or bottom-mounted, and its height can be adjusted inside the tank for optimal mixing efficiency.

The Alfa Laval Rotary Jet Mixer injects circulated liquid through two or four nozzles, creating a three-dimensional mixing pattern that ensures dispersion and homogeneity throughout the entire tank volume.

Since the Rotary Jet Mixer is reengineered from rotary jet head tank cleaning machines, it can also act as a Cleaning-in-Place (CIP) device that provides high-impact cleaning of the entire tank interior.

• Reduces sulphite mixing time. Besides improved hygiene, organic wineries can make better use of the reduced sulphite dosing when using the Iso-Mix system by ensuring that the sulphite is more quickly and homogenously dispersed into the tank. Mixing time can be cut from hours to just minutes – even for large tanks.

• Shortens fermentation time. The Alfa Laval Iso-Mix system also reduces fermentation time by: (1) boosting yeast proliferation with air injection; and, (2) by maintaining yeast cells in suspension and active with constant substrate renewal, while simultaneously keeping fermentation temperature homogeneous between the tank bottom and tank top. Trials performed in collaboration with wineries showed that recirculation of yeast with the Iso-Mix system for 10 minutes every hour reduces fermentation time for white wine from 26 days to 14 days, while maintaining temperature below 13°C for optimal flavour development.

• Minimises capital expenses and installation costs. Because the duties performed by the Alfa Laval Rotary Jet Mixer only require operation for a few hours at a time, a single circulation pump can be used alternately for several tanks, thereby minimising capital expenses and installation costs. 

• Reduces cleaning downtime and saves water and effluents. The Alfa Laval Rotary Jet Mixer also works as a highly efficient tank cleaning device. The high jet impact of CIP fluids through the nozzles effectively does away with the need for hard manual labour or extended cleaning cycles with low impact spray balls. Total cleaning and rinsing time, which can reach up to two hours for very large wine tanks, is cut in half. For large wineries with many tanks, the use of a central CIP system enables complete cleaning and sanitisation in automated sequences while minimising environmental impact with reduced water consumption and effluents.

• Improves clarification. Finally, by maintaining a homogeneous suspension of yeast lees after the end of fermentation, the Iso-Mix system improves the regularity and efficiency of highspeed separators during clarification. 

Quality organic wine, every time

Getting the best possible wine from organic grape juice requires a time-tested, cost- efficient and versatile solution. Proven and widely used in the brewery industry, the Alfa Laval Iso-Mix system meets the requirements of hygiene, injection of ingredients and sparging for beer processing. These are, more or less, the same process requirements for producing traditional wine as well as organic wine.

By replacing mechanical agitators and bottom mounted sparging systems, the Iso-Mix system simplifies the design and cleanability of the interior of the fermentation tank and cuts the associated capital expenditures.

It also does away with the inertia of the liquid in the tank, which prevents achieving homogeneity throughout the liquid volume during the agitation of yeast cells, the addition of ingredients, or sparging.

What’s more, it reduces the time, water and energy spent for cleaning and disinfection. This translates into more uptime and higher yield.

 At the heart of Iso-Mix technology is the Alfa Laval Rotary Jet Mixer. Easy to install on new and existing tanks, the Rotary Jet Mixer is available in different sizes and is easy to adapt to meet the requirements of a broad range of tank capacities. 

Getting the best from the grapes

Alfa Laval provides a comprehensive range of technologies, solutions and equipment that wine-making companies and distilleries worldwide rely on in their operations.

These include extraction, concentration by evaporation, thermovinification and all kinds of heat treatment, crossflow filtration, stabilisation, heating and cooling, and recovery and clarification by centrifugal separation. We also supply solutions for fluid handling, mixing and tank cleaning as well as filling and packaging.