Contents:

Introduction

In the wine industry, differences among grape cultivars are well-known and are critical in creating desired wine styles. However, there is little information on which other small fruit and berry cultivars are best for winemaking. 

Our research aimed to delineate differences among fruit wines made from distinct cultivars within each fruit species and to determine those cultivars best-suited for winemaking. We made 28 single-cultivar wines from fruit grown at our research center in western Montana. Species used included aronia (A.K.A. black chokeberry), black currant, dwarf sour cherry, and haskap. Wine samples were sent to wine experts and enthusiasts for evaluation.

Overall, we found that most cultivars yielded wine ranging from acceptable to high-quality, but a few cultivars were significantly more or less preferred by a majority of tasters.

Methods

In 2020, we made 28 single-cultivar wines using fruit harvested in 2019 at the Montana State University-Western Agricultural Research Center (WARC) (Corvallis, MT; 46°18'54.04" N -114°06'52.67" W). These single-cultivar batches were made using 3 distinct cultivars of aronia (A.K.A., black chokeberry), 7 black currant, 4 sour cherry, and 14 haskap (A.K.A., honeyberry). Fermentation was done in two rounds. The first round included the aronia, black currant, and sour cherry cultivars; the second round included all 14 haskap cultivars. While all batches followed the same basic recipes for fruit wine fermentation, the ferments for each species of fruit followed a slightly different recipe to account for differing flavors and chemistry among the fruits. We followed this general formula for fermentation of all batches:

  1. For each batch of must, 8-10 lbs (depending on recipe) of frozen fruit were thawed in separate, 4-gallon square, food-grade plastic buckets.
  2. A nylon mesh drawstring bag was used to contain fruit in each bucket. Bagged fruit were pressed repeatedly with an extra-large potato masher (or similar tool) until most juice was expressed from the fruit and a juicy, pulpy mixture filled the bucket.
  3. A sugar and water solution was made for each batch by boiling half the volume of water and all of the sugar called for in the recipe (slightly different for each specific recipe). The solution was boiled slowly until sugar dissolved, removed from the heat, and allowed to sit for a few minutes. The prepared solution was poured into the bucket of crushed fruit, and the mixture was stirred thoroughly. The remaining volume of cold water was added to the mixture to lower its temperature.
  4. The appropriate types and amounts of tannin, enzymes, and potassium metabisulfite were added to each batch (according to specific recipes), mixed thoroughly, covered, allowed to rest for 24 hours before pitching yeast.

  1. Before pitching yeast, each batch was tested for pH and Brix/specific gravity (SG) to establish a baseline for each batch. If necessary, acidity was adjusted with malic acid, depending on pH of each mixture (with a target pH of ~3.3 to 3.4), and/or sugar levels were adjusted depending on Brix/SG (with a target of ~22-24 °Bx). Note: Baseline Brix/SG allows estimation of alcohol content at the end of the fermentation and will assist in tracking fermentation progress.
  2. Pitch yeast:
    1. For each batch of must, about one third of a 200 ml beaker was filled with warm water.
    2. Approximately 3 g yeast nutrient (e.g., Go-Ferm Protect Evolution) and ~3 g yeast (yeast strain will depend on the fruit species) were added to the beaker and mixed well.
    3. Enough juice from the corresponding must was added to fill the beaker about half full. Contents were miixed thoroughly and allowed to rest at least 15 minutes, until the mixture foamed actively for a few minutes.
    4. The mixture was poured into the corresponding must and mixed thoroughly with a large stirring utensil.
    5. pH and Brix/SG were tested again for each batch.
    6. Each bucket was covered with a plastic bucket lid that had been prepared by drilling a hole large enough to accommodate an airlock. The batches were allowed to sit for 4-5 days and were stirred once per day.
  3. Every two days, a representative number of batches were tested for pH and Brix/SG to track fermentation progress. 
  4. Once the majority of ferments decreased to about half of their original Brix/SG (~4-5 days), ~2 g Fermaid K (a nutrient mix that includes nitrogen) was mixed with ~50-100 ml of water and stirred into each batch.
  5. Brix/SG and pH were monitored every two days. After ~2 weeks, the bags of must were removed from each bucket; all juice was allowed to drain, but fruit were not squeezed tightly. The wine was allowed to settle overnight, after which it was racked into 1-gallon glass carboys using a siphon.
  6. When no sugar remained (<0 degrees Brix or <1.000 specific gravity), the alcoholic fermentation was complete. Each batch was tested to determine the levels of free SO2 using a Vinmetrica instrument. To stabilize the wine, potassium metabisulfite was added to each batch to achieve 60 ppm free SO2 (the FermCalc app was used to determine exact amounts). Note: some fruit species (e.g. aronia) had higher levels of sucrose, a non-fermentable sugar. In those cases, Brix/SG were monitored and the fermentation was considered complete when the sugar level remained stable for at least 2 weeks. 

  1. In preparation of bottling, free SO2 levels were monitored and potassium metabisulfite was added as needed to keep free SO2 levels near 60 ppm.
  2. For batches that needed clarification (e.g., cherries and haskaps), Sparkolloid was dissolved in boiling water (according to product label instructions) and mixed into wine. Wine was allowed to settle for at least 1 week.
  3. The day before bottling, SO2 levels were checked and adjusted accordingly to reach 60 ppm. For additional microbial stabilization, potassium sorbate was added at a rate of 0.75 g per gallon of wine.
  4. On the day of bottling:
    1. 375 ml bottles and synthetic corks were sanitized with StarSan immediately before bottling;
    2. Wine was racked from carboys into a bucket with a filling spigot (and a food-grade plastic tube attached), being careful to avoid racking any sediment along with the wine.
    3. For each species, a few bench trials are recommended to determine whether backsweetening is necessary. When necessary, a pre-made simple syrup (1-to-1 ratio of water to sugar) was added to the wine to achieve the desired percent sugar (our highest sweetening percentage was ~2%, calculated with FermCalc) and thoroughly stirred.
    4. Wine was sampled for final pH and titratable acidity data.
    5. Wine was bottled using the bucket spigot, being careful to position the tube at the bottom of the bottle to avoid oxygenation during bottling, and leaving approximately 1 inch of headspace. Bottles were topped off with Argon gas and corked using a manual corker.
    6. Each bottle was labeled with the corresponding code for each fruit species and cultivar.

While all ferments followed this general process, there were distinct differences among the different fruit types in terms of recipe details, fruit-specific chemistry, and human error along the way. Some notable differences for each fruit type are noted below:

  • Due to aronia’s higher concentration of sorbitol (a non-fermentable sugar) all three batches of aronia wine never reached true dryness (=<0 °Bx, =>1.000 SG). Additionally, each batch ended up with different sugar levels, some varying as much as 4 °Bx among them.
  • The varying levels of residual sugar in each of the wines are a challenge for backsweetening to an equal and acceptable sweetness among the wines. Because one of the batches finished at ~7 °Bx, we chose the average sweetness among the batches and added enough simple syrup to each of the other aronia batches to bring them to 3% sugar. This produced wines that were sweeter than many of our evaluators preferred, thus affecting their evaluations of the aronia wines.

  • Multiple evaluators reported undesirable aromas, which could have been influenced by addition of potassium metabisulfite (can impart a slightly sulfuric aroma) for stabilization at the bottling stage.
  • Multiple evaluators reported slight effervescence in their samples. This is typically explained by wines being stored longer than intended in less-than-ideal conditions, leading to minor refermentation.

  • No major issues were reported by a majority of tasters for the haskap wines.

  • Too much sugar was mistakenly added to one of the batches (cultivar Juliet) at the beginning of the fermentation process. As a result, by the end of the fermentation, the ‘Juliet’ batch was noticeably more alcoholic than the other batches. Thus, it was likely more difficult to evaluate the other batches in relation to the ‘Juliet’ wine because of its comparatively “hot” flavor.
  • Many evaluators could not get past the medicinal flavor of the cherry wines. We received feedback from some tasters that, had the wines been sweeter (we only sweetened to ~2% sugar), the medicinal flavor and alcohol “heat” might have been better balanced.

Groups of tasters from across Montana were recruited to evaluate each of the 28 single-cultivar wines. These 13 groups collectively totaled ~70 tasters representing wineries, cideries, breweries, and other wine enthusiasts around the state. The wines were distributed in one large delivery that included all 28 wines, but evaluators were instructed to break up the tastings into smaller sittings of no more than 8 wines, so as to avoid “palate fatigue.” Each bottle of wine was labeled with a code rather than its cultivar in an attempt to increase evaluation objectivity. These codes corresponded to the data fields on the evaluation sheets.

The tasting packages included printed evaluation sheets and step-by-step guidance on working through the tastings. Each wine was rated on a 5-point scale for six criteria: appearance, aroma, body, taste, finish, and overall impression. Space was provided for additional comments about each wine, in addition to questions clarifying tasters’ overall preference for wine in general, and whether or not they detected a noticeable difference among the cultivars within each fruit species.

Once the groups of evaluators had completed their tastings, they mailed their completed evaluation sheets to our research team for analysis.

Results

Data from all of the completed evaluation sheets were recorded in a spreadsheet for statistical analysis. There were two analyses for each fruit type: 1) one that used all evaluators' scores and did not control for each evaluator’s average score, and 2) one that only analyzed data from evaluators that tasted all wines of a given fruit type and also controlled for each taster’s average score. While the results from each analysis show generally the same results, the later analysis has more power to find differences among the single varietal wines by controlling for the individual preferences of each evaluator. 

Key points:

  • The majority of tasters detected differences among the cultivars in all 4 species, with slightly lower percentages noting differences among cherry varietal wines (73%) than black currant (81%), aronia (85%), and haskap (87%) single varietal wines.
  • While this study was not designed to compare among the fruit types, the results suggest that sour cherry and black currants wines were less preferred than aronia and haskaps. For cherry and black currant wines, no cultivar was rated as good-excellent by a majority of tasters while cultivars of aronia and haskaps had 52 to 60% of tasters rate as good-excellent.

Table 1. Simple 1-5 Scoring
Criteria
5
4
3
2
1
Appearance
Clear, appropriate color, brilliance, no off colors
....
....
....
Cloudy, off colors
Aroma
Complex, many detectable aromas, intense
....
....
....
Little or no aroma, off aromas
Body
Perfect texture and weight feel in the mouth
....
....
....
Too little or too much texture or weight feel in the mouth
Taste
Good balance and structure, several flavors detectable
....
....
....
Little balance and structure, few flavors
Finish
Flavors linger after swallowing, smooth and rich aftertaste
....
....
....
Taste and flavors end abruptly, no aftertaste
Overall impression
Excellent!
Good
OK
Not good
Gross!

Aronia

Among aronia cultivars, Autumn Magic wine consistently scored higher than the wine made from the Viking and McKenzie cultivars. This is particularly interesting because ‘Autumn Magic’ is an ornamental cultivar that tends to have lower yields and smaller berries than ‘Viking’ and ‘McKenzie’, which are higher-yielding commercial cultivars. 

Evaluators generally preferred the wine of 'Autumn Magic', and described the flavors of aronia wines as woodsy, earthy, and/or peppery, and sometimes too sweet.

Table 2. Aronia wine evaluation results 1

(data derived from all evaluators' scores; not controlled for each evaluator’s average score)
Cultivar
Average Rating
Acceptable (% 3+)
Exceptional (% 4+)
Off-putting (% 2-)
Autumn Magic
3.6
70
53
30
Viking
2.9
50
17
43
McKenzie
2.8
43
30
57
Aronia/Black
Currant mix
2.6
59
31
41

Table 3. Aronia wine evaluation results 2

(data only from evaluators that tasted all wines of this fruit type; controlled for each taster’s average score)
Cultivar
Overall
Appearance
Aroma
Body
Taste
Finish
Autumn Magic
3.6 a
4.3 a
3.2 a
3.4 a
3.5 a
3.4 a
Viking
2.9 b
4.2 a
2.8 b
2.9 b
2.7 bc
2.8 b
McKenzie
2.8 bc
4.0 a
2.7 b
2.9 b
2.9 b
2.7 bc
Aronia/Black
Currant mix
2.6 c
4.1 a
2.6 b
2.7 b
2.6 c
2.5 c

Means of evaluation scores (0-5 scale) followed by different letter were significantly different

To learn more about aronia and how to grow it in Montana, see the small fruits section of our website: Aronia Research

Black Currant

Among black currant cultivars, wines made from Whistler, Tahsis, and Tofino were rated higher than wines made from Nickola and Titania. A significant number of evaluators commented on the astringency and sourness of many of the cultivars, which was often unappealing to the tasters. In reading evaluators’ comments, it seems there may also have been minor refermentation in some bottles that were stored for longer than intended or in less-than-ideal conditions (e.g. too warm of an environment), in addition to notes about unpleasant aromas, which we suspect were caused by the addition of potassium metabisulfite at bottling (which, while completely safe, can impart a sulfuric odor).

Evaluators generally preferred wines of Whistler and Tahsis cultivars, describing the color as "brilliant ruby" and "garnet", and flavor/aroma as "balanced", and "fruity". The least preferred cultivars were Nicola (M12) and Titania. Off-putting aromas were described as "sulfur", "gunpowder", "plastic", "green pepper", "grapefruit". 

Table 4. Black currant wine evaluation results 1

(data derived from all evaluators' scores; not controlled for each evaluator’s average score)
Cultivar
Average Rating
Acceptable (% 3+)
Exceptional (% 4+)
Off-putting (% 2-)
Whistler
3.4
81
42
17
Tahsis
3.2
72
35
24
Tofino
3.1
75
39
22
Cheakamus
3.0
71
28
25
Blackcomb
2.9
61
24
36
Nicola (M12)
2.7
54
25
42
Titania
2.5
49
13
47

Table 5. Black currant wine evaluation results 2

(data only from evaluators that tasted all wines of this fruit type; controlled for each taster’s average score)
Cultivar
Overall
Appearance
Aroma
Body
Taste
Finish
Whistler
3.4 a
4.4 a
3.2 a
3.4 a
3.3 a
3.3 a
Tahsis
3.2 ab
4.3 ab
3.2 a
3.1 ab
3.1 ab
3.1 ab
Tofino
3.1 abc
4.3 ab
3.1 a
3.1 b
3.1 ab
3.0 b
Cheakamus
3.0 bc
4.2 ab
3 a
3.0 bc
3.1 ab
2.9 b
Blackcomb
2.9 cd
4.3 ab
3.1 a
3.1 ab
2.8 bc
2.9 b
Nicola (M12)
2.7 de
4.1 b
2.2 b
2.8 cd
2.7 cd
2.5 c
Titania
2.5 e
3.9 c
3.1 a
2.7 d
2.5 d
2.5 c

Means of evaluation scores (0-5 scale) followed by different letter were significantly different

NOTES: Whistler and Tahsis were preferred over some cultivars. Nicola was not preferred due to off-putting aromas. Titania was not preferred due to off-putting taste. 

To learn more about black currants, see the small fruits section of our website: Black Currant Research.

Sour Cherry

Among sour cherry cultivars, wines made from dwarf sour cherries (Carmine Jewel, Romeo, and Juliet) were rated higher than the sour cherry cultivar (Lutowka Rose) in most categories. As mentioned before, however, most evaluators found the cherry wines to be relatively unbalanced and unappealing, due to their medicinal flavors (often compared with the flavor of cough syrup) and pronounced alcoholic “heat.” 

Table 6. Sour Cherry wine evaluation results 1

(data derived from all evaluators' scores; not controlled for each evaluator’s average score)
Cultivar
Average Rating
Acceptable (% 3+)
Exceptional (% 4+)
Off-putting (% 2-)
Carmine Jewel
3.0
71
33
31
Romeo
2.8
62
26
40
Juliet
2.7
48
22
52
Latowka Rose
2.3
36
16
66

Table 7. Sour Cherry wine evaluation results 2

(data only from evaluators that tasted all wines of this fruit type; controlled for each taster’s average score)
Cultivar
Overall
Appearance
Aroma
Body
Taste
Finish
Carmine Jewel
3.0 a
4.2 a
2.9 ab
3.1 a
3.0 a
2.9 a
Romeo
2.8 ab
4.2 a
3.1 a
2.9 ab
2.9 ab
2.8 ab
Juliet
2.7 b
3.8 b
2.5 c
2.7 b
2.6 b
2.6 b
Latowka Rose
2.3 c
3.5 b
2.7 bc
2.4 c
2.2 c
2.2 c

Means of evaluation scores (0-5 scale) followed by different letter were significantly different

To learn more about sour cherries, see the small fruits section of our website: Dwarf Sour Cherry Research.

Haskap

All haskap cultivar wines were rated as acceptable or better by a majority of tasters, but there were slight differences among cultivars. With regard to overall impression scores, wines made from ‘Keiko’ and ‘Kawai’ were rated higher than ‘Indigo Gem’, ‘Wild Treasure’, and ‘Blue Goose’. The majority of haskap varietal wines scored similarly to the top cultivars and better than ‘Wild Treasure’ and ‘Blue Goose’. Our most important conclusions from the comparison of haskap cultivars for winemaking are that: 1) most cultivars will make acceptable if not exceptional wines, and 2) the two lowest-rated cultivars, Blue Goose and Wild Treasure, are the exceptions and should be avoided for winemaking, likely because their fruit tends to impart medicinal (quinine) flavors.

Table 8. Haskap wine evaluation results 1

(data derived from all evaluators' scores; not controlled for each evaluator’s average score)
Cultivar
Average Rating
Acceptable (% 3+)
Exceptional (% 4+)
Off-putting (% 2-)
Kawai
3.6
81
53
11
Keiko
3.6
84
49
7
79-91
3.5
90
54
16
41-75
3.5
91
40
7
Taka
3.5
84
32
7
Aurora
3.4
86
53
21
85-19
3.4
90
49
16
Tana
3.4
77
49
14
Borealis
3.4
86
47
19
SMB
3.4
75
46
16
Solo
3.3
74
35
18
Indigo Gem
3.2
79
40
26
Wild Treasure
3.1
63
33
28
Blue Goose/
Blue Corn mix
2.7
60
19
47

Table 9. Haskap wine evaluation results 2

(data only from evaluators that tasted all wines of this fruit type; controlled for each taster’s average score)
Cultivar
Overall
Appearance
Aroma
Body
Taste
Finish
Keiko
3.8 a
4.5 ab
3.5 a
3.5 ab
3.7 a
3.5 a
Kawai
3.7 ab
4.5 a
3.4 a
3.6 a
3.5 ab
3.3 ab
Chito (41-75)
3.5 abc
4.5 abc
3.3 a
3.4 abcd
3.4 abcd
3.3 ab
Honeybunch (79-91)
3.5 abc
4.4 abcde
3.7 a
3.3 abcde
3.4 abc
3.3 ab
Tana
3.7 bc
4.5 abcd
3.3 a
3.4 abcd
3.4 abcd
3.2 abc
Borealis
3.4 bc
4.3 abcde
3.2 a
3.3 abcd
3.4 abcd
3.2 abc
SMB
3.4 bc
4.3 cde
3.2 a
3.3 abcd
3.2 bcde
3.1 bc
Taka
3.4 bc
4.5 abcd
3.5 a
3.3 abcd
3.2 bcde
3.2 abc
85-19
3.3 cd
4.4 abcde
3.2 a
3.4 abcd
3.4 abcd
3.1 bc
Aurora
3.3 cd
4.3 de
3.2 a
3.4 abc
3.3 abcd
3.0 bcd
Solo
3.3 cd
4.3 bcde
3.3 a
3.1 de
3.1 cdef
3.0 bcd
Indigo Gem
3.2 cd
4.4 abcde
3.2 a
3.2 cde
3.0 def
3.0 bcd
Wild Treasure
3.0 de
4.3 abcde
3.5 a
3.3 bcde
2.9 ef
2.9 cd
Blue Goose/
Blue Corn mix
2.9 e
4.2 e
3.2 a
3.0 e
2.8 f
2.7 d

Means of evaluation scores (0-5 scale) followed by different letter were significantly different

 

Select comments from evaluators:

“Initial flavor really good/balanced, but ended tart.”

“Complexity to the aroma. Notes of sweet and earth. Nice body with more fullness. Some balance between acidity and sweetness. Finish is not too heavy.”

“Flavorful and balanced. Clarity very nice.”

“Very well balanced, great acidity and tannic finish. Full fruit, ripe berry flavors.”

“Green pepper, smells vegetal, tomate wine.” (Blue Goose/Blue Corn)

“Aroma bell pepper. Too spicy and acidic.” … “Made me quiver.” (Wild Treasure)

To learn more about haskaps, see the small fruits section of our website: Haskap Research.