Conventional And Non-Conventional Yeast Strains With Potential For The Production Of NAB/LAB.

When it comes to the fermentation of wort, selecting the right yeast is just as important as selecting the recipe style. Choosing the wrong strain could skew the beer into a different category, resulting in a less than ideal result, a few key factors in selecting the right yeasts are; ester production, attenuation, temperature ranges, top or bottom fermenting, POF+, STA1+, failing to choose a suitable strain may result in undesirable sensory profiles and characteristics, and/or over/under-attenuation.

When brewing NAB/LAB, selecting the right strain is even more crucial, as over attenuation may result in higher ABV%, and a neutral profile may not create the right flavour characteristics, leaving the brewer with a plain, thin beer.

You can find on this page a list of proven, and untested yeast strains that may have potential in creating great results. The information provided has been best detailed based on available information from manufacturers, listing where available; genus, attenuation, suited styles, and sensory characteristics.

The untested use of some of these strains may result in undesirable results, causing loss within a brewers brewhouse, consideration must be taken whether a particular strain is suitable the the brewer.

Beer Strains

Beer Strains Section

Cider And Wine Strains

Cider and Wine Strains Section.

Beer Strains & Information

With the increase in non-Saccharomyces species/novel strains making their way into the production of non-alcoholic/ultra-low alcohol beer, the use of these varieties holds great potential for the NAB/LAB sector in the fermentation of wort. With a trial and selection process, yeast manufactures have been able to isolate specific strains of these novel strains to assist in low fermentability in NAB/LAB production.

In this catalogue, you will find multiple strains available from different manufactures that may aid brewers in creating lower alcohol beers, whilst these strains have not all been tested in NAB/LAB production, results may vary, creating un-desirable characteristics such as phenolic of flavours (POF) and risk cross-contamination. Where applicable, these strains “may” contribute positive flavour/aroma profiles. Brewers are to use the information provided as a “guide” only, as some of the information may be unavailable from manufactures, or incorrect at the time of publishing, and should be used on smaller test batches, as to not spoil large quantities of beer, resulting in costly losses, if the brewer is unsure if the use of these yeasts are suitable to their brewery, it is advised not to use them, and proceed with “standard” strains to avoid waste or loss.

Information regarding compatibility on these strains may be updated in time, if myself, or other brewers test these strains against wort fermentation and compatibility and contribute to this paper to assist in clarification on flavour/aroma profiles, fermentability, off flavours, and the overall outcome of the beer.

YEAST Manufacturer/Strain	Factor	Result	ESTERS/ FLAVOURS
Fermentis SafAle™ S33 Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Fruity driven strain gives a high mouthfeel and body to the beer. Yeast with a medium sedimentation forms no clumps but a powdery haze when resuspended in the beer.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	68-72%
	USES	Blonde/Pales, Amber, Brown Ales, Stout, American and British Ales, Belgian Ales, Hazy IPA’s, Session IPA’s, New England IPA’s.
	NA COMPATIBLE	YES
Fermentis SafBrew™ LA‑01 Saccharomyces cerevisiae var. chevalieri	CONSUMES MALTOSE	NO	Very Low ester production and is characterized by a subtle aroma profile. POF +, not to be used with wheat, Suitable to most beer styles, this yeast does not assimilate maltose and maltotriose but assimilates simple sugars (glucose, fructose, and sucrose).
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	13-17%
	USES	POF +, not to be used with wheat, Suitable to most beer styles.
	NA COMPATIBLE	YES
Fermentis SafAle™ F-2 Cask & Bottle Conditioning Yeast Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Neutral Flavour and aroma.
	CONSUMES MALTOTRIOSE	Minimal
	ATTENUATION	High (Simple Sugars)
	USES	Well suited for primary fermentation of sweeter fruit beers or full-bodied, malty ales. Also, Dry Ciders, Mead, Hard Seltzer.
	NA COMPATIBLE	YES
Lallemand London™ Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Moderate ester production that lets the flavours and aromas of malt and hops shine through.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	Medium
	USES	Milds, Bitters, Irish Reds, English Brown ales, Porters and Sweet Stouts, Pale Ale, IPA, New England IPA, Hazy IPA, Ambers, American Ales.
	NA COMPATIBLE	YES
LalBrew CBC-1™ Cask & Bottle Conditioning Yeast Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Neutral Flavour and aroma.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	High (Simple Sugars)
	USES	Well suited for primary fermentation of sweeter fruit beers or full-bodied, malty ales. Also, Dry Ciders, Mead, Hard Seltzer
	NA COMPATIBLE	YES
Lallemand Windsor™ Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Produces a balanced fruity aroma and imparts a slight fresh yeasty flavour. Beers created with Windsor are usually described as full-bodied, fruity English ales, sweet.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	Medium
	USES	Milds, Bitters, English Brown ales, Porters, Stouts, Pale Ale, IPA, New England IPA, Ambers, American Ales.
	NA COMPATIBLE	YES
Whitelabs WLP4650 Metshnikowia Reukaufii	CONSUMES MALTOSE	NO	Attenuating to 20-25% in brewer’s wort and not utilizing maltose or maltose polymers, in co-fermentations it has been shown to drop gravity and pH of the fermentation faster, accentuate and modulate the flavour and aroma profile and soften the perceived bitterness of the finished product.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	20-25% Brewers Wort
	USES	Non/Low Alcoholic beer
	NA COMPATIBLE	YES
Whitelabs WLP603 Torulaspora Delbrueckii	CONSUMES MALTOSE	NO	Does not ferment maltose or other larger sugars and will only ferment glucose, sucrose, and fructose. The profile of this strain has high ester production and will lend well to styles such as a fruit-forward IPA or Saison.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	20%
	USES	Fruity, ideal for Belgian, Saison styles or IPAs
	NA COMPATIBLE	YES
Whitelabs WLP686 Zygosaccharomyces lentus	CONSUMES MALTOSE	NO	Little ester production, neutral flavour, and aroma.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	20%
	USES	Non/Low alcoholic beer
	NA COMPATIBLE	YES
Whitelabs WLP618 Saccharomycodes ludwigii	CONSUMES MALTOSE	NO	Neutral strain with some ethyl acetate production, Lower ethyl acetate production compared to similar strains.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	20%
	USES	Non/Low alcoholic beer
	NA COMPATIBLE	YES
Whitelabs WLP002 English Ale Yeast Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Residual sweetness accentuates malt character along with mild fruity esters, adding complexity to the flavour and aroma of finished beers. Slight diacetyl production is common. Due to this strain’s high flocculation, the beer will finish clear.
	CONSUMES MALTOTRIOSE	N/A (Possibly Negative)
	ATTENUATION	63-70%
	USES	Pale ale, IPA, Brown Ale, English Bitter
	NA COMPATIBLE	YES
Whitelabs WLP011 European Ale Yeast Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Low ester production gives it a clean profile, with little to no sulphur production. Low attenuation helps to contribute to the malty character.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	65-70%
	USES	Altbiers, Kolsch-style ales, malty English-style ales, and fruit beers.
	NA COMPATIBLE	YES
Whitelabs WLP036 Dusseldorf Alt Ale Yeast Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	It produces clean, malty German brown and amber ales. This strain keeps the contribution of hop bitterness in the background while promoting sweet malt notes.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	65-72%
	USES	Altbier, Cream Ale, Kolsch, Red Ale
	NA COMPATIBLE	YES
Whitelabs WLP546 Marañón Canyon Wild Cacao Yeast Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	The fruity, phenolic, and wild-like characteristics of this strain make it an ideal choice for farmhouse and Saison-style beers.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	65-70%
	USES	Saison, Wild Specialty Beer
	NA COMPATIBLE	YES
Whitelabs WLP611 New Nordic Ale Yeast Saccharomyces Cerevisiae x Torulaspora Delbrueckii	CONSUMES MALTOSE	YES	This culture is a unique blend of three yeast strains (two belonging to Saccharomyces cerevisiae and one Torulaspora delbrueckii). Although originally thriving in the simple sugar fermentations such as wine and cider, this blend ferments maltose as well and has been used to make a series of true New Nordic Beers. This blend has a specific aroma profile, especially at higher temperatures
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	65-75%
	USES	Belgian Saison, Belgian Pale Ale, Weizenbock, Weissbier, German hefeweizen, Wine, Mead, Cider
	NA COMPATIBLE	YES
Whitelabs WLP820 Oktoberfest/Märzen Lager Yeast Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	This strain is ideal for producing malty lagers. Residual sweetness further helps promote malt nuances while contributing to a balanced finish.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	65-73%
	USES	Lagers, Pilsners, Helles, Märzen
	NA COMPATIBLE	YES
Wyeast 1469 West Yorkshire Ale ™ Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Produces ales with a full chewy malt flavour and character, but finishes dry, producing balanced beers. Moderate nutty and stone-fruit esters.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	67-71%
	USES	Bitters, ESB, Mild Ales
	NA COMPATIBLE	YES
Wyeast 1332 Northwest Ale ™ Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Produces a malty and mildly fruity ale with good depth and complexity.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	67-71%
	USES	Pale Ales, IPA, Amber Ale, Stout, Blonde Ale
	NA COMPATIBLE	YES
Wyeast 1099 Whitbread Ale™ Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	A mildly malty and slightly fruity fermentation profile. Good flocculation characteristics, this yeast clears well without filtration. Low fermentation temperatures will produce a clean finish with a very low ester profile.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	68-72%
	USES	British ales, stout, IPA, Blonde ale, Bitters
	NA COMPATIBLE	YES
Wyeast 1187 Ringwood Ale™ Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Distinct fruit esters with a malty, complex profile. Flocculation is high, and the beer will clear well without filtration. A thorough diacetyl rest is recommended after fermentation is complete. This strain can be a slow starter and fermenter.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	68-72%
	USES	Porter, Brown Ales, Dark milds, Stouts, IPAs
	NA COMPATIBLE	YES
Wyeast 1768-PC English Special Bitter™ Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Produces light fruit and ethanol aromas along with soft, nutty flavours. Exhibits a mild malt profile with a neutral finish.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	68-72%
	USES	Bitters, IPAs, Stout,
	NA COMPATIBLE	YES
Wyeast 1728 Scottish Ale™ Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Suited for the strong, malty ales of Scotland. This strain is very versatile and is often used as a “House” strain as it ferments neutral and clean. Higher fermentation temperatures will result in an increased ester profile.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	69-73%
	USES	Scottish Ales, Stout, IIPA, Specialty Ale
	NA COMPATIBLE	YES
Wyeast 1968 London ESB Ale™ Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Extremely flocculent yeast produces distinctly malty beers. Attenuation levels are typically less than most other yeast strains which results in a slightly sweeter finish. Ales produced with this strain tend to be fruity, increasingly so with higher fermentation temperatures. A thorough diacetyl rest is recommended after fermentation is complete.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	67-71%
	USES	Bitters, Ales, Fruit Beers, English IPA
	NA COMPATIBLE	YES
CHR-Hansen NEER^® Pichia Kluyveri	CONSUMES MALTOSE	NO	Enhanced fruit flavours (esters/thiols) and medium production of polysaccharides, converts monosaccharides into specific and desirable flavour compounds, without production of diacetyl.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	N/A
	USES	NAB/LAB production
	NA COMPATIBLE	YES

You can utilise any strain of yeast for fermentation, but it is better practice to choose a suitable strain, that is either Maltose and/or maltotriose negative to reduce the attenuation of the sugars available in the wort. Avoid choosing a strain that tests positive for the STA1 gene, (Ref. 1) The presence of the STA1 gene causes the yeast to secrete glucoamylase, an enzyme which hydrolyses dextrins and starches into fermentable sugars. The yeast is now a “hyper attenuator” as it ferments beer beyond what ordinary brewer’s yeast is capable.

Beer contaminated with even a small amount of S. diastaticus will first ferment normally with the expected level of attenuation. After packaging, the secreted glucoamylase will continue to break down these complex carbohydrates into glucose over the subsequent months. The glucose will then be fermented by all yeasts present, producing alcohol and CO2. Since the beer is already packaged, the generated CO2 causes over-pressurization, leading both to gushing and the more dangerous effects of package failure.

(Ref. 2)

Dry or full-bodied beers?

FIND THE RIGHT BALANCE BETWEEN RESIDUAL SUGARS AND FINAL ALCOHOL. (Table 1.)

Almost all of our yeast strains guarantee a medium/high attenuation rate: around 78-84%. If you want to obtain a beer with a higher attenuation and a low level of residual sugars, SafAle™ BE-256 or SafAle™ BE-134 will be the obvious choices. Likewise for high-density beers, SafAle™ HA-18 will allow

a very high attenuation. However, if you want to obtain a medium level of residual sugars, SafAle™ S-33 will fit perfectly.

Residual sugars:

LOOKING FOR YEASTS WHICH LEAVE SOME SPECIFIC SUGARS BEHIND? (Table 2.)

SafAle™ S-33 will leave most of the maltotriose. Conversely, SafAle™ BE-256 consume almost all of it. Furthermore, SafAle™ WB-06 and SafAle™ BE-134 are S. cerevisiae var. diastaticus and will convert dextrins into fermentable sugars.

Esters:

Some specific SafAle™ strains develop a neutral profile, while other yeasts express more fruity flavour (Table 3.) – mainly SafAle™ BE-256 and SafAle™ WB-06.

Wine/Cider Strains & Information

With the increase in non-Saccharomyces species/novel strains making their way into the production of non-alcoholic/ultra-low alcohol beer, the use of wine, cider and mead yeast varieties hold great potential for the NAB/LAB sector in the fermentation of wort. With a trial and selection process, yeast manufactures have been able to isolate specific strains of these novel strains to assist in low fermentability in NAB/LAB production.

In this catalogue, you will find multiple strains available from different manufactures that may aid brewers in creating lower alcohol beers, whilst these strains have not been tested in the fermentation of wort, results may vary, creating un-desirable characteristics such as phenolic of flavours (POF), or Acetic acid (Vinegary) and risk cross-contamination. Where applicable, these strains “may” contribute positive flavour/aroma profiles. Brewers are to use the information provided as a “guide” only, as some of the information may be unavailable from manufactures, or incorrect at the time of publishing, and should be used on smaller test batches, as to not spoil large quantities of beer, resulting in costly losses, if the brewer is unsure if the use of these yeasts are suitable to their brewery, it is advised not to use them, and proceed with common “beer” strains to avoid waste or loss.

Fermentis SafCider™ AC-4 (Apple Crisp) Saccharomyces Bayanus	CONSUMES MALTOSE	YES	Intensely fresh aromatic profile (apple, floral) with a crisp mouthfeel enhancing cider structure. Please note that those observations are based on French cider recipe trials.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	N/A
	USES	For sweet and dry ciders.
	NA COMPATIBLE	Yes (Least preferred)
Fermentis SafCider™ AB-1 (Apple Crisp) Saccharomyces Bayanus	CONSUMES MALTOSE	YES	Delicate aromatic profile combining fresh (apple) and elaborated fruit (applesauce) notes with a balanced mouthfeel respecting cider structure. Please note that those observations are based on French cider recipe trials.
	CONSUMES MALTOTRIOSE	NO
	ATTENUATION	N/A
	USES	For all types of sweet and dry ciders.
	NA COMPATIBLE	Yes (Least preferred)
Fermentis SafŒno™ HD T18 Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Terpenols and β-damascenone release supported by a balanced production of acetate & ethyl esters, which strengthens wines’ complexity. It particularly enhances fresh floral and citrus fruit notes.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	N/A
	USES	Muscat, Riesling, Pinot Gris
	NA COMPATIBLE	YES
Fermentis SAFŒNO™ CK S102 Saccharomyces Cerevisiae	CONSUMES MALTOSE	YES	Thanks to its high ester production, it is an ideal choice to value neutral grape varieties to obtain white and fruity rosés wines with different aroma profiles depending on the fermentation temperature. High volatile thiols release abilities.
	CONSUMES MALTOTRIOSE	N/A
	ATTENUATION	N/A
	USES	Sauvignon Blanc, Muscat, Riesling
	NA COMPATIBLE	YES
Fermentis SAFŒNO™ GV S107 Saccharomyces cerevisiae x Saccharomyces bayanus	CONSUMES MALTOSE	YES	High Glycerol production, (7-8g/L), promotion of floral and fruity higher alcohols and esters (rather than isoamyl acetate), sweet long-lasting finish, variety helps releasing floral and citrusy aromas (terpenes and C13-Norisoprenoids) from grapes.

Esters:

Amyl (Acetate): An ester of acetic acid, C 7 H 14 O 2, pleasant fruity/banana odour, used as a flavouring agent, as a paint and lacquer solvent, and in the preparation of penicillin. Also called banana oil.
Ethyl (Acetate): Characteristic sweet, pleasant fruity odour and is used in glues, nail polish removers, and in the decaffeination process of tea and coffee. Ethyl acetate is the ester of ethanol and acetic acid.
Isoamyl (Acetate): Isoamyl acetate has a strong odour which is described as similar to both banana and pear.
Phenylethyl (Acetate): Rose and honey scent and a raspberry-like taste, it is widely used in perfume compositions, from everyday soap and detergent perfumes to fine cosmetic fragrances, room-sprays, deodorants, etc.

(Ref. 1)

Saccharomyces eubayanus was discovered in Patagonia and identified as the non-S. cerevisiae parental species of hybrid S. pastorianus lager-type beer brewing yeasts [1,2]. While S. cerevisiae is strongly associated with biotechnological processes, including dough leavening, beer brewing and wine fermentation [3], S. eubayanus has only been isolated from the wild [4–6]. Beer brewing is performed with wort, a complex substrate containing a fermentable sugar mixture of 15% of the monosaccharide glucose, 60% of the α-di-glucoside maltose and 25% of the α-tri-glucoside maltotriose [7]. While many S. cerevisiae and S. pastorianus strains utilize all three sugars, S. eubayanus isolates do not utilize maltotriose [8–10].

Applicability of a maltotriose-consuming S. eubayanus strain for lager beer brewing S. eubayanus strains are currently used for industrial lager beer brewing [9]. To test the evolved strain IMS0750 under laboratory-scale brewing conditions, its performance was compared with that of its parental strain CBS 12357T in 7 L cultures grown on high-gravity (16.6˚ Plato) wort (Fig. 1). After 333 h, IMS0750 had completely consumed all glucose and maltose, and the concentration of maltotriose had dropped from 19.3 to 4.7 g L-1 (Fig. 1). In contrast, CBS 12357T did not utilize any maltotriose. In addition to its improved maltotriose utilization, IMS0750 also showed improved maltose consumption: maltose was completely consumed within 200 h, while complete maltose consumption by strain CBS 12357T took ca. 330 h (Fig. 1). Consistent with its improved sugar utilization, the final ethanol concentration in cultures of strain IMS0750 was 18.5% higher than in corresponding cultures of strain CBS 12357T (Fig. 1). Brewing-related characteristics of IMS0750 were further explored by analysing production of aroma-defining esters, higher alcohols, and diacetyl. Final concentrations of esters and higher alcohols were not significantly different in cultures of the two strains, with the exception of isoamyl acetate, which showed a 240% higher concentration in strain IMS0750 (Table 1). In addition, while the concentration of the off-flavour diacetyl remained above its taste threshold of 25 μg L-1 after 333h for CBS 12357T, it dropped below 10 μg L-1 for IMS0750 (Table 1).

Fig. 1 Extracellular metabolite profiles of S. eubayanus strains CBS 12357T and IMS0750 in high-gravity wort at 7 L pilot scale. Fermentations were performed on wort with a gravity of 16.6˚Plato. The average concentrations of glucose (squares), maltose (triangles), maltotriose (diamonds) and ethanol (circles) are shown for duplicate fermentations of CBS 12357T (blue) and IMS0750 (red). The average deviations are indicated (S7 Data File).

Table 1. Concentrations of alcohols, esters, and diacetyl after fermentation of wort with a gravity of 16.6˚P by S. eubayanus strains CBS 12357T and IMS0750. The data correspond to the last time point (330 h) of the fermentations shown in Fig 5. The average and average deviation of duplicate fermentations are shown for each strain.

(Ref. 2)

Saccharomyces bayanus is a yeast species used for fermentation, particularly in winemaking [10]. Despite that it belongs to the Saccharomyces genus and shows genetic similarity to other species that belong to this taxon, they may vary in terms of oenological properties and the ability to synthesise volatile compounds [11]. A comparison made between S. bayanus, and S. cerevisiae showed that wines fermented by S. bayanus have higher flavour intensity [10]. S. bayanus produces larger amounts of 2-phenylethanol, ethyl lactate, 2-phenylethyl acetate, and other acetate esters.

In apples, fructose is the predominant sugar [14], and in the case of the analysed samples, this carbohydrate was present in the highest concentration—above 60% of total sugars. In addition to fructose, apples also contain glucose and sucrose, and the relative amounts of these sugars differ significantly between apple cultivars. The sugar profiles of raw materials may affect the fermentation efficiency and concentration of residual sugar [14] as it happened in our study—most of the sugars were utilised during fermentation, in fermented musts resulting in small amounts of glucose (from 0.03 to 0.68 g/L) and fructose (from 0.87 to 3.24 g/L). The concentration of glucose after fermentation was approximately the same in all samples since it is used first during fermentation. Fructose is used after glucose [15], and since its level was higher in Topaz in unfermented must, more of that sugar remained after fermentation.

The acetic esters of higher alcohols are produced during the condensation of acyl-CoA and higher alcohols are formed by alcohol transferases (AATase). S. cerevisiae has two AATases (Atf1p and Atf2p), and in S. bayanus cells, another AATase (Lg-Atf1p) is present. Atf1p is the most important ester synthase for the production of acetate esters, e.g., isoamyl acetate, phenylethyl acetate, and, of C3 to C8, acetate esters [28]. For this reason, isoamyl acetate was detected in the highest concentration in brandies obtained from musts fermented by S. bayanus; nevertheless, its amount was also high in other samples (from 1.5 to 55.9 mg/L 100% vol. alcohol). Patelski et al. (2014) [29] also proved that plum brandies obtained from musts fermented by S. bayanus had higher amount of isoamyl acetate (8.00 mg/L 100% vol. alcohol), compared to spontaneous fermentation (3.01 mg/L 100% vol. alcohol). Similarly, 2-phenylethyl acetate was found in the highest concentration in spirits obtained from musts fermented by S. bayanus (Table 3). This compound is an important volatile in distillates with a rose and honey scent and a raspberry-like taste [30]. It can be concluded that S. bayanus is a good acetate esters producer.

Amyl alcohols were detected in higher concentrations in samples obtained from musts fermented spontaneously and in the lowest in samples fermented by S. bayanus. Presence of propanol, hexanol, heptanol, 1-octanol, and 1-nonanol resulted from the reduction of aldehydes to alcohols during fermentation [34].

Fermentation with S. bayanus is known to produce much more acetaldehyde in obtain wines than fermentation with S. cerevisiae [37].

Brandies produced from musts fermented with S. bayanus obtained the highest average scores for “overall note” (more than 4.0 pt.) regardless of the apple cultivar used for the distillery industry. It means that this strain of yeast could be feasible for the distillery industry. That strain was shown to be the best acetate ester producer (Table 3) and those compounds are associated with a flower and fruit aroma which is considered acceptable.

Samples fermented by S. cerevisiae demonstrated the highest fermentation efficiency and ethanol content. In our study, the best acetate ester producer was S. bayanus.

(Ref. 3) To assess the robustness of the strains towards difficult fermentation conditions, i.e., High sugar concentration (and content in the most difficult to assimilate fermentable sugars, i.e., fructose), low pH, nutrient deficiency, low temperature… Figure 2 shows the kinetics as well as the remaining sugars at the end of the fermentation in the hard cider.

Fig.2 Kinetics follow-up through the American hard dry cider recipe.

The strain SafCider™ TF-6 clearly stands apart from the other strains as it was not able to finish the fermentation and typically left ~25 g/L of sugars, among which fructose was a major part. This feature was observed in most of all matrices, as TF-6 was only able to finish the fermentation till dryness in the English cider (high YAN, low tannicity, then less inhibition and more O2 availability, high temperature), highlighting the bigger needs of this particular strain and the fact that the selection can be crucial depending on the cidermaker target. A higher sensitivity to high concentration of SO2 (50 mg/L maximum) is as well to be noticed for this strain

All basic analytical parameters at the end of the fermentation have been determined. Among the most interesting ones, the acidity profile is of particular interest as it reflects the metabolic behaviour of the strain that could have a real impact on the organoleptic profile.

Fig.3 Acidity profiles through the English dry cider recipe.

Figure 3 shows the acidity profiles of strains in the English cider recipe. Most significant with SafCider™ AB-1 and maybe not as much with the other strains, we could see that some strains are able to consume the major organic acid present in apples, i.e., the malic acid, in significant amount through the malo-ethanolic pathway; and thus, decreasing the total acidity and its feeling.

To the contrary, some strains, such as SafCider™ AC-4, are preserving this acidity and maintain a crispy feeling (observed but not shown here). Moreover, the ability of strains to produce acetic acid during fermentation from the glycolysis pathway can also affect the aromatic profile, degrading its quality at too high concentration (vinegar flavours). For this attribute, all strains were selected for their low production with always the SafCider™ TF-6 being a “clean” strain towards deviations like SO₂ and acetaldehyde production as well.

In addition to higher alcohols, two major types of aromatic compounds are produced by yeast strains during fermentation and have a significant impact on the aromatic profile of all beverages: (1) the acetate esters, whose most famous and abundant one is the isoamyl acetate with its distinctive banana and candy notes and which is recognized as an overall aroma enhancer; and (2) the ethyl esters, whose most abundant ones are the linear chain ethyl esters from 4 to 10 carbons (C4-butanoate, C6-hexanoate, C8-octanoate and C10-decanoate) and which confer more discrete but more complex floral and fruity characters. Huge differences in the release of these compounds can drastically affect the flavour perceptions of beverages, the same applying for ciders.

Fig.4 Strain aromatic profiles for all recipes regarding isoamyl acetate and ethyl esters (C4, C6, C8 and C10) odour active values (= concentration/perception threshold). *: Sole recipe in which TF-6 was able to dry the sugars. NA = Non-Available.

In Figure 4, all matrices have been taken to compare the aromatic behaviour of the strains in different conditions.

We noticed big differences between strains; and even if aromatic compounds concentrations were of course impacted by the recipe and more specifically the amount of sugars fermented (especially for isoamyl acetate whose acetate part is directly linked to the glycolysis pathway), we could extract common trends. Except for the English cider, SafCider™ TF-6 showed always higher production of isoamyl acetate than others. This will be illustrated in terms of flavour but also aromatic intensity in the last paragraph of this article.

For the English cider only, SafCider™ TF-6 was indeed able to dry the sugars and not leave any residual sugars, suggesting a strong relationship between the stress generated at the end of the fermentation and the aroma produced. SafCider™ AC-4 showed particularly high but quite stable ethyl esters production (driven by ethyl octanoate – fruity/floral), hypothesizing a reliable complexity in the flavours. SafCider™ AB-1 and particularly SafCider™ AS-2 increased their ester production along with the difficulty of the recipe with SafCider™ AB-1 being on the low values, more respecting the raw material.

Relying on the expertise of IFPC and their trained taste panel specialized on French traditional sweet ciders, professional tastings have been carried out on French cider experiments, both stopped with around ~30 g/L of residual sugars (called “Brut” ciders in French). The specificity of this tasting was to assess first the global fruitiness of the ciders with two major descriptors: (1) “Fruity/Floral” corresponding to fresh fruit (apple, pear, banana…) feeling; and (2) “Cooked fruits” related to ripe or processed fruits (like compote), aromas that are not necessarily looked for but adding complexity to the final cider. After this evaluation, it was then asked to tasters to detail fresh and cooked fruit notes to identify the aromatic drivers for each strain and to evaluate off-flavours as well, such as phenolic and sulphury aromas. Finally, a simple evaluation of the basic tastes was done: Sweet, acid, bitter and astringent.

From these tastings, SafCider™ TF-6 (especially) and SafCider™ AS-2 were scored as the highest in fresh but also cooked fruits, whereas SafCider™ AC-4 was judged less expressive and predominantly oriented towards freshness; and SafCider™ AB-1 was more discrete (data not shown).

More interesting were the detailed fresh fruits perceived by tasters as shown in Figure 5. Obviously, sensory characterization of all ciders was driven by detection of apple notes, but SafCider™ TF-6 scored high for most of the fruits, especially banana-pear and red fruits. SafCider™ AS-2 and SafCider™ AC-4 respectively exhibited more citrus and floral notes, whereas SafCider™ AB-1 was mainly centred on apple.

Fig.5 Detail of fruity/floral notes for the French sweet cider.

Both these general and detailed notes are actually quite well related with the production of aromatic compounds highlighted in the previous paragraph; with higher production of isoamyl acetate by SafCider™ TF-6, offering thus more aromatic intensity but enhanced aromatic complexity towards the other fruits as well; followed by SafCider™ AS-2 and SafCider™ AC-4, the latter producing mainly ethyl esters such as ethyl octanoate; which could explain these red fruits and specifically floral notes. SafCider™ AB-1 was the less exuberant and expressing more the raw material thanks to its quite discrete aroma production

Fig.6 Fermentis cider strains baseline map based on French sweet cider recipe.

Together with mouthfeel attributes assessment (data not shown) confirming higher acidity feeling for SafCider™ AC-4 in line with its acidity maintenance and the sweetness feelings for SafCider™ TF-6 and SafCider™ AS-2 possibly linked to their high candy-like aromatic intensity and their higher remaining fructose level (higher sweetening power than glucose or saccharose), Fermentis suggested the map in Figure 6 to describe the impact of these 4 yeast strains and to serve as a baseline for cidermakers in their choices.

For this purpose, Fermentis focused its research on the selection of valuable strains dedicated for ciders. SafCider™ AB-1 (Apple Balanced) will suit for all types of balanced ciders even under difficult fermentation conditions. SafCider™ AS-2 (Apple Sweet) will bring to sweet and dry ciders complex aromatic profile between fresh and cooked fruits and a rounder mouthfeel. SafCider™ AC-4 (Apple Crisp) will be applied for highly fresh and crisp sweet or dry ciders. SafCider™ TF-6 (Tutti Frutti) will be dedicated to intensely fruity but rather sweet and round ciders!

What Is Glycerol?

(Ref. 4) – Glycerol (C3 H8 O3) is a non-volatile compound which has no aromatic properties, but which significantly contributes to wine quality by providing sweetness and fullness (Ribereau-Gayon et al. 1972). It is the most import by-product of alcoholic fermentation in quantity after ethanol and carbon dioxide (CO2).

Why is Glycerol important in wine?

Glycerol has a favourable impact on wine quality. It is non-aromatic due to its non-volatile nature but can contribute to the sensory properties of wine depending on the concentration. Wines lacking in body can benefit from an increased glycerol production to improve the sensory characteristics. The production of glycerol is also very important to maintain the redox potential of the yeast which is vital during fermentation.

Results:

The amount of glycerol usually formed by Saccharomyces cerevisiae in wine varies between 2–11 g /L but normal concentrations are in the range 4–9 g/L. Glycerol production can be controlled by the choice of the appropriate yeast strain. We have studied the production of glycerol by wine yeast strains, under controlled laboratory conditions (synthetic must 230g/l of sugar (glucose/ fructose), no nutritional deficiencies (300 mg/l of YAN) at 24°C) and mimicking winemaking conditions. The results are the following: (Figure 7.) 1. There is a wide range of different production of glycerol depending on the yeast strain. We can classify selected wine yeast into 3 categories: low, medium, and high glycerol producers. At the lowest range, the yeast GHM is at 6.22 g/L and the highest, the S6U at 12.62 g/L. Most selected yeast are found to be medium producers (between 7 and 8 g/L), a few high producers such as Cross Evolution, VRB, CLOS, BC and 43 (between 8.08 and 9.6 g/L). Those with the highest production can be particularly interesting in wines which have lower mouthfeel and structure. It is important to consider the other characteristics of the wine yeast as they might not be suitable for all wines.

Fig. 7 Glycerol Production

What are Thiols, and why are they important?

(Ref. 5) – Thiols, also known as mercaptans, are sulphur-containing organic compounds with a sulphur atom bound to a hydrogen atom. Scientists first identified them in hops in the early 2000s, focusing on three, that winemakers have known about for decades. One, 4-mercapto-4-methylpentant-2-one (4MMP), smells and tastes of box tree, black currant, and ribes. It is also known as 4-methyl-4-sulfanylpentan-2-one (4MSP). Another, 3-mercaptohexan-1-ol (3MH), is often described as exotic, smelling of rhubarb and citrus. And the third, 3-mercaptohexyl acetate (3MHA), is reminiscent of passion fruit and guava. Thiols, along with other compounds such as terpenes and esters, contribute to the enjoyable odours in “hop-forward” beer styles. Although very small amounts of thiols are present in beer, a little bit of these compounds goes a long way toward achieving a hoppy flavour and fruity aroma. Too much of these compounds can lead to off flavours.

Effects of Low Nitrogen Stress on the Amount of Higher Alcohols in Wine in Saccharomyces Cerevisiae.

(Ref. 6) – Nitrogen is an indispensable nutrient for Saccharomyces cerevisiae and plays a pivotal role in the growth and metabolism of yeast. Higher alcohols are by-products of alcoholic fermentation by Saccharomyces cerevisiae, and they are generally considered as important flavour compounds in wine. Higher alcohols are generally formed by two pathways: sugar metabolism and amino acid metabolism. Higher alcohols are monohydric alcohols containing more than three carbon atoms, including propanol, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-phenylethanol [4]. In general, higher alcohols can contribute to the improvement of wine quality when the content of higher alcohols in wine is less than 300 mg/L. However, when the higher alcohol content is higher than 400 mg/L, it usually has a disadvantage effect on the wine flavour and the health of the consumer.

In nitrogen deficiency conditions, yeast growth and fermentation speed are limited. A low initial concentration has been shown to cause slow and sluggish fermentations.

Nitrogen in beer

(Ref. 7) – Other than sugar, nitrogen is probably the most important macronutrient required for yeast health and growth. Nitrogen deficiency is associated with several fermentation difficulties including stuck and incomplete fermentations, whereas excess nitrogen is related to the production of both off flavours and beer spoilage.

Nitrogen is often assessed by measuring Free Amino Nitrogen (FAN) or to give it its other name Primary Amino Nitrogen (PAN). FAN or PAN assays, test for the concentration of amino acids and small peptides that are utilized by yeast for cell growth and proliferation. Together with ammonia, FAN/PAN makes up what is known as Yeast Assimilable Nitrogen or YAN.

FAN compounds are formed naturally during malting and mashing by the action of protein degradation enzymes on hordein, a protein found in the grain. The level of amino acids available in the wort relies on several variables including grain variety, as well as malting and mashing conditions, but the overall types of amino acids available will be similar among all whole malt worts. Likewise, the specific amino acids taken up by yeast follow a similar pattern during fermentation, although environmental changes can alter this.

Using adjuncts, such as corn and rice, dilute FAN levels in the wort while increasing fermentable sugars. Consequently, high-adjunct worts are nitrogen deficient, and fermentation can be adversely affected, leaving high levels of sugars in the beer. FAN levels in the wort are often regarded as the best indicator of potential yeast growth and are therefore directly related to fermentation efficiency. Yeast need FAN to grow and reproduce, so theoretically the more you have the quicker your yeast will grow, the stronger it will be and the more alcohol your yeast will produce.

Yeast consumes most of the FAN in the first 36-40 hours of fermentation, during its propagation phase. As they do so they can produce a range of metabolic by-products some of which affect flavour and stability of the finished beer.

Conventional And Non-Conventional Yeast Strains With Potential For The Production Of NAB/LAB.

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Wine/Cider Strains & Information

Esters:

What Is Glycerol?

Why is Glycerol important in wine?

Results:

What are Thiols, and why are they important?

Effects of Low Nitrogen Stress on the Amount of Higher Alcohols in Wine in Saccharomyces Cerevisiae.

Nitrogen in beer

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