Professional Editorial: Alcohol-free wine presents challenges in filtration and high quality assurance

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The manufacturing of non-alcoholic wines presents a selected problem for producers, because it differs significantly from the basic winemaking course of.

By Dr. Ilona Schneider and Felix Marzolph, MBA

Non-alcoholic (NA) variations of sometimes alcoholic drinks have gotten increasingly common. Along with alcohol-free beer, the fan base for NA wines and glowing wines has additionally seen a rise. Whereas the market share for these wines remains to be lower than one %, NA glowing wine already has a five-percent share of the market, in accordance with German wine manufacturing journal Der Deutsche Weinbau—and the development is rising. The manufacturing of non-alcoholic variants presents a selected problem for producers, because it differs significantly from the basic winemaking course of. The wines are additionally totally different merchandise when it comes to sensory expertise.

Alcohol-free wine is outlined as a beverage with a most of 0.5 % alcohol by quantity. In wine, nevertheless, alcohol is a necessary protecting issue in opposition to dangerous microorganisms, equivalent to yeasts and micro organism. For non-alcoholic variants, this implies the beverage will likely be inclined to such microorganisms and due to this fact continually run the chance of changing into unstable. Consequently, filtration has a distinctly necessary activity: sustaining the microbiological stability of alcohol-free wine till bottling and past.

Filterability and bacterial load within the manufacturing course of

Each the filterability and the microbiological properties of alcohol-free wines had been examined as a part of two separate grasp theses, by Sven Horter (Hochschule Geisenheim College) and Felix Marzolph (Weincampus Neustadt). The target of those scientific papers was to find out the filter index and complete bacterial depend of various alcohol-free wines. As well as, the 2 papers examined which filtration steps would guarantee microbiological stability.

The manufacturing and filtration system check consisted of eight steps: from the tanker, to the dealcoholization course of and subsequent tank storage, then to the filtration course of with crossflow storage filtration (CFF), intermediate tank storage and two-stage nice and last filtration.

Samples had been taken from the tanker and once more after passing by means of the dealcoholization system, after CFF and after the two-stage cartridge filtration. Samples had been then analyzed. To establish the filterability 0.85 gallons (3.2 liters) of the respective wine had been added to the gadget’s storage container and filtered utilizing a 0.45-μm flat filter membrane (check membrane) at a continuing strain of 14.5 psi (1.0 bar). Based mostly on the measured filtrate portions, the wine was then labeled as “simple to filter” with a filter index worth of ≥3,000 mL, “common filterability” with a filter index worth of two,500-2,999 mL, or “troublesome to filter” with a filter index <2,500 mL.

The microbiological checks of the samples had been carried out in a laboratory utilizing membrane filtration. Every pattern was filtered utilizing a 0.45-µm flat filter membrane below sterile situations after which incubated on totally different tradition media in agar plates. The expansion of microorganisms that would contaminate the wine was counted after an outlined incubation interval of 5 days at a temperature of 81°F (27°C). 

Initially, 4 totally different wines with a quantity of 6,600 gallons (25,000 liters) every had been analyzed: a German crimson wine, a German white wine, a Spanish Merlot and a Spanish Cabernet Sauvignon. 

Tab. 1: Outcomes of the filter index measurements and the entire cell depend. Feedback: CFU: colony-forming models; > 100: greater than 100 CFU/ml; > 200: CFU/ml now not countable, overgrown

This revealed that three of the 4 wines had been already labeled as “troublesome to filter” following the preliminary sampling from the tanker. Solely the German white wine achieved a filter index of three,000 mL and was due to this fact “simple to filter.” 

For the entire wines, the filter index fell considerably, to values between 200 and 693 mL, following dealcoholization. The CFF allowed the 2 German wines to realize a filter index of three,000 mL, whereas the index worth of the Spanish wines elevated solely barely and remained “troublesome to filter.” It was solely by means of the mixture of depth filter cartridges and downstream membrane filter cartridges that each one wine batches may obtain a filter index of three,000 mL and be labeled as “simple to filter.”

Notably, throughout the microbiological checks, excessive (>100 CFU/mL) to very excessive (>200 CFU/mL) microbiological hundreds had been noticed in three of the wines after they had been delivered to the tank. Solely the Spanish Cabernet Sauvignon demonstrated a decrease cell depend of fifty CFU/mL. After dealcoholization, the entire wines had been topic to very excessive a great deal of >200 CFU/mL. It was solely following the two-stage cartridge filtration that the microbiological load of all of the wines might be diminished to the sterile vary of 0 CFU/mL, which means no yeast or micro organism that would contaminate the drinks might be re-introduced.

Affirmation trial

In an extra check utilizing 6,600 gallons (25,000 liters) every of a Spanish Merlot, French Chardonnay and European rosé, the microbiological outcomes with regard to bacterial load had been confirmed. Though the load for the Chardonnay and the rosé decreased after dealcoholization, they nonetheless exhibited excessive values of >100 CFU/mL. For the Merlot, the load was very excessive all through your entire manufacturing course of. It was solely following the two-stage cartridge filtration that the colony-forming models had been diminished to zero, permitting for a sterile bottling strategy of the alcohol-free wines.

Tab. 2: Outcomes of figuring out the entire cell depend. Feedback: All values in CFU/ml; CFU: colony-forming models;
>100: greater than 100 CFU/ml; >200: CFU/ml now not countable, overgrown

Two-stage nice and last filtration

Because the check outcomes present, the manufacturing strategy of alcohol-free wine is a selected problem when it comes to filterability and microbiological stability. The elimination of the alcohol considerably reduces filterability — even the German white wine delivered as “simple to filter” solely achieved an index worth of >700 mL as soon as the alcohol had been eliminated. A wine that’s troublesome to filter can simply develop into a value issue for producers. 

The tougher the wine is to filter, the simpler it’s for the membrane filter cartridges to develop into clogged. This then results in extra frequent cleansing or filter substitute. Throughout this time, machines are at a standstill and bottling is delayed.

As well as, the non-alcoholic wine loses its safety in opposition to microorganisms that would contaminate the beverage. A contamination worth of >200 CFU/mL signifies a really excessive bacterial load. This was detected in numerous samples. Producers should set in place particularly stringent sanitary necessities for filtration programs if the alcohol is lacking as an inhibitor. That is the one means a microbiologically secure NA wine might be bottled to stop the secondary fermentation and sensory modifications attributable to microbiological exercise inside crammed bottles.

This collection of checks has proven that the CFF course of was unable to realize sterile ranges in any pattern. When it comes to filterability, CFF proved useful for a few of the samples, however was not ample for the entire wines analyzed. 

It was solely potential to acquire sterile wines following two-stage nice and last filtration utilizing depth and membrane filter cartridges. The depth filter cartridges retained nearly all of the particles and microorganisms, whereas the downstream membrane filter cartridges, so-called “police filters,” guarantee microbiological stability. This two-stage nice and last filtration is completely important for the manufacturing strategy of alcohol-free wines. It’s the solely means to make sure the microbiological high quality and sustainable marketability of the alcohol-free beverage, and due to this fact to supply high quality assurance of the very best stage.

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Dr. Ilona Schneider, enologist, brings greater than 25 years of expertise in enology and beverage remedy. She most lately works as a product supervisor for beverage remedy for Eaton Applied sciences GmbH within the wine filtration enterprise. [email protected]

Felix Marzolph, MBA, brings over 10 years of expertise in winemaking and wine manufacturing in numerous technical roles the place most lately he works as a gross sales supervisor for Eaton Applied sciences GmbH within the wine filtration enterprise. [email protected]

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