Bitter Apples For Cider Making - An Alternative

Bitter Apples For Cider Making - An Alternative.
Richard Badcock 1 *, Gabriel Gressie 1 , Maxwell Burslem 1 , Neil Barker 2 .
1 Cascade Brewery, Hobart, Foster’s Australia.
2 Abbotsford Brewery, Melbourne, Foster’s Australia
Abstract
Traditional alcoholic apple ciders often combine varieties of “bittersweet”,
“bittersharp” and “culinary” apples to give mouthfeel balance between bitterness,
acidity, and alcohol content. The bitter component is derived from apple
polyphenols which confer astringency to cider, producing an effect which is
similar to that of tannins from oak contact in wine production.
These bitter apple varieties are quite specialised, having poor appeal as
table or dessert fruit, and tend to be grown exclusively for cider production. The
lead time and infrastructure required to establish such perennial horticultural
crops is significant, leading to a relatively expensive product with slow response
to increasing demand.
At the Cascade Brewery we have identified immature dessert and culinary
apples as an alternate source of apple polyphenols, having typically six times the
concentration of tannins that so called “bitter” varieties contain. These immature
apples are widely available from table fruit production at the thinning stage, very
early in the growing season.
Methods for fruit collection, storage, processing and use have been
developed, together with final cider product flavour matching, to commercialise
this alternate raw material as an economical source of apple polyphenols.
Importantly, since the process utilises an existing surplus resource, it also offers
considerable flexibility in meeting demand changes at short notice.
Key Words: cider, apples, bittersweet, polyphenol.
Introduction
Apples originated in the Middle East or Central Asia, and have been
cultivated for more than 4000 years. Initially cultivated for eating, they have also
been used for at least 1000 years to make the fermented alcoholic apple juice
product known as cider, in Southwest England and Northwest France (Lea).
There are more than 7500 known cultivars of apple (Elzebroek). While a
majority are for eating, there are a significant number of cultivars that are
principally for cooking or cider making. In general terms, table fruit tends to be
quite sweet with a low to moderate acidity; cooking fruit is similar but may have a
higher acidity level. Traditional cider apples may have either low or high acidity,
however, they are also typically distinguished by an elevated polyphenol
content.(Lea), often loosely referred to as “high tannin” It has been postulated
that high tannin fruit cultivars were initially selected for cider making because of
disease resistance advantages for the tree, or possibly because of anti-bacterial
properties in the final beverage. (Lea)

There are six main polyphenol classes found in apples. Lea states that,
two of these, the anthocyanins and flavonol glycodises ,are found mainly in the
skin and do not play a significant role in juice or cider products. Fig 1, Fig 2.
Fig 1. Quercetin 3 glucoside – skin polyphenol
Fig 2. Cyanidin 3 Glucoside - skin polyphenol
Lea further states that the remaining 4 classes of polyphenols are:
• Phenolic acids: principally chlorogenic and p-coumaroyl quinic acid
• Dihydrochalcones: phloretin and its glycosides, principally phloridzin
• Catechins: principally (-) epicatechin
• Procyanidins: principally the 4 beta 8 linked epicatechin series. e.g. dimer
B2, with smaller amounts of other-linked and (+) catechin/(-) epicatechin
series.

These 4 classes of compounds do play an important role in the qualities of apple
products.(Lea, Shahidi)
Fig 3. Chlorogenic acid
Fig 4. Phloridzin
Fig 5. (-) Epicatechin
Fig 6. Procyanidin B2

A key property conferred on cider by these polyphenols, particularly the
procyanidins, is the taste perception of bitterness or astringency.
Bitterness, also referred to as “hard” tannin, is associated with lower levels
of polymerization and low procyanidin molecular weight.
Astringency, also referred to as “soft” tannin, is associated with increasing
levels of polymerization and molecular weight.(Lea).
In today’s beverage market, ciders can be made from juice or juice
concentrates derived solely from culinary or dessert apples, or solely from
traditional cider apples. But a considerable number of ciders are made from a
blend of both culinary / dessert and traditional cider apples.
Commercial culinary apple juice concentrate (8 times concentrated = 71
brix) typically contains 1500 – 3000 mg/L polyphenol. This is equivalent to 190 –
375 mg/L at fresh juice strength. Lachman et al (2006) have reported total
polyphenol in juice from table apples ranging from 78 to 697 mg/l with
considerable variation between varieties but even more between analysis
methods. He compared the EBC total polyphenol method with the Folin-
Ciocalteau (FC) method.
Commercial European bittersweet apple concentrate typically contains
9000 – 16000 mg/L polyphenol. This is equivalent to 1100 – 2000 mg/L at fresh
juice strength.
Recent increased popularity of cider both in Europe and Australia lead to
an acute shortage of so called “bittersweet” apple juice and apple juice
concentrate, resulting in poor availability and increased cost
Apples are a perennial crop, so there is substantial cost, infrastructure and
time delay required to increase crop capacity if demand for a particular cultivar
(or group of cultivars) exceeds supply. As there was little or no prospect of
immediate reliable supply, a search for suitable substitutes was undertaken.
Potential commercial sources of polyphenol that were considered for
inclusion in cider production were tea polyphenol, oak tannins, oak chips, and
grape polyphenol. These were taste trialed at a lab scale in a cider base, and
found to be a poor flavour match to cider produced using traditional bittersweet
apple concentrate. There were also physical stability problems with cider
containing these alternatives.
Another potential source was crab apples. These have traditionally been
used in some styles of alcoholic cider. Crab apples have been noted by Shahidi
to produce juices with 390 – 1350 mg/L chlorogenic acid. As chlorogenic acid
comprises around 6-10% of total polyphenols (Shahidi) this implies a total
polyphenolics level in juice from mature crab apples of 3900 – 22000 mg/L. This
compares to reports of juice from table varieties of apple which, when mature,
have implied total phenolics ranging from 15 – 3000 mg/L. However, there are no
commercial quantities of crab apples grown in Tasmania, and juice concentrates
from crab apples also are not known to be available.
Brown at al (2001) have reported total polyphenol levels of 3000 – 6000
mg/kg in apple skin material, and around 15000 mg/kg in apple leaf material. The
proportions of polyphenol classes was not identified, however, it would seem

from the observations of Lea, that they are likely to be different to that normally
found in juices and ciders.
Elevated levels of apple polyphenols in immature fruit has been reported
(Martin, Tanabe et al, Gordon Brown pers comm.) Much previous work has
focused on purification of these components and their application as
antioxidants, alternatives to tea polyphenols, and for physiological effects.
(Tanabe et al, Kanda et al). These polyphenols include chlorogenic acid,
catechin, epicatechin, rutin and condensed tannins (Kanda et al 1998). They are
essentially the same compounds that occur in juice and cider products derived
from mature fruit, but at higher concentrations.
It was recognised that immature fruit from crop thinning operations could
potentially be processed using regular juice production methods, and
concentrated into a “super” bittersweet apple concentrate for inclusion as a
substitute raw material in cider making.
Martin identifies that commercial quantities of apple thinnings are
potentially available, and has reported the relationship between total polyphenol
content, apple variety, size and thinning date for some cultivars under Tasmanian
conditions. (Fig 7 and Fig 8).
Polyphenol mg/L vs Date by Variety
16.0
14.0
mg/L Polyphenol (Thousands)
12.0
10.0
8.0
6.0
4.0
2.0
Red Delicious spur
Hi Early Red Delicious
Democrat
Crofton
Fuji
Granny Smith
Golden Delicious
0.0
22 NOV
'95
28 NOV
'95
04 DEC
'95
13 DEC
'95
05 JAN
'96
Fig 7. Adapted from Martin (1997)

Fruit diameter vs Date by Cultivar
Average Fruit Diameter (mm)
45.0
40.0
35.0
30.0
25.0
20.0
15.0
10.0
5.0
Red Delicious spur
Hi Early Red Delicious
Democrat
Crofton
Fuji
Granny Smith
Golden Delicious
0.0
22 NOV
'95
28 NOV
'95
04 DEC
'95
13 DEC
'95
05 JAN
'96
Fig 8. Adapted from Martin (1997)
Shahidi et al (1995) note that the major losses of polyphenols in the
processing of apples is brought about by oxidation, and further, that holding pulp
under non-oxidative conditions for up to three hours improves the extraction of all
phenolic compounds from pulp into juice. Gordon Brown performed the analysis
of polyphenol referred to in Fig 7 (personal communication), and confirmed that
these extractions were performed using metabisulphite at the maceration stage.
Lea makes the observation that there are a range of reactions which can remove
polyphenols from apple juice products, including polyphenol - protein complexing,
oxidative polymerization, acid catalysed disproportionation, and aldehyde cross
linking. Gelatine fining of apple juice products to prevent haze formation is a
specific example of protein – polyphenol complexing.
Lea further observes that “all of these reactions can be prevented by the
use of sulphur dioxide, which acts variously as an anti-oxidant, as a blocking
nucleophile, or to form aldehyde-bisulphite adducts.”
It was decided to undertake full scale processing plant trials on immature
apple thinnings to produce Tasmanian Little Green Apple concentrate (TLGA), in
parallel with lab scale investigations into the polyphenol levels of a range of apple
cultivars available at the National Apple cultivar museum orchard at Grove,
Tasmania. This was undertaken from September 2007 through until late January
2008, and examined a selection of table apple, traditional cider apple, and crab
apple cultivars as they developed from flowering onwards.

Experimental
Cultivar evaluations: Fruitlet samples were collected by cultivar. Some
were sub-sampled into “large” or “small” fruitlets to assess the relative influence
of size and date. Fruitlet samples were measured for average diameter, then
weighed. 100 - 200 grams of the fruitlets were then cut into small pieces before
grinding and mixing with a hand held “Bamix” unit. Grinding with, and without,
metabisulphite at circa 300 mg / kg was trialed. A sample of the ground pulp was
then placed in a disposable 10 mL syringe and approximately 2 mL of liquid
collected through a 0.45 um, 25 mm dia, cellulose acetate filter disc.
.
Total Polyphenol levels were measured using a standard Fosters method
(Costanzo, 2003) based on the ASBC and EBC International Method.
The juice samples were diluted 10 fold by volume with distilled water by
modifying the method and including 150 uL of sample instead of the usual 1500
uL, and increasing the distilled water to make up the same volume
The following aliquots were added to a disposable cuvette:
• 800 uL CMC / EDTA reagent
• 150 uL of sample
• 50 uL of Ferric Reagent (samples only)
• 50 uL Ammonia reagent
• 1450 uL of distilled water (use 1500 uL for blank)
After mixing and allowing a reaction time of 10 minutes, the absorbance
was measured against a reagent blank at 600 nm wavelength in a
spectrophotometer. Final result is calculated by multiplying corrected
absorbance at 600 nm x 547 x dilution factor to give results in mg/L.
Processing plant trials: A total of 185 tonnes of fruit thinnings were
collected over a period of 5-7 weeks from mid November until the end of
December. These were collected into waist belt held picking bags, before
consolidation into 0.4 tonne holding bins. The bins of fruitlets were hydro-cooled,
then stored in cool store at 4 degrees C until delivery to the processing plant on
the day of processing.
Fruit was processed on 6 Dec, 13 Dec, 21 Dec and 8-10 January. Milling
occurred using a Rietz mill (10 mm screen) with addition of sodium
metabisulphite solution at milling to give a level of approximately 300 mg/kg
SO2. Some additional water was also added at milling to facilitate pumping to
the mash holding tanks. Pectolytic mash enzyme was added at a rate of
approximately 300 mL/Tonne, before holding for 1 – 2 hours at 20 – 25 degrees
C. Juice was extracted using a Bucher HPX5005i fruit press, then flash
pasteurised into agitated fining tanks where fining agents silica sol and bentonite
were applied. The juice was then cross-flow filtered in a Bucher “Ministar –metal”
unit employing Graver technologies filter elements having 0.1 micron pore size
titanium oxide membranes supported on 316 sintered stainless steel. Finally, the
juice was concentrated in an APV rising / falling film plate evaporator to around

70 brix, before packing into 200 litre polyethylene drums and freezing at -23 deg
C for storage.
Juice samples were collected throughout processing stages and filtered
through a 0.45 um cellulose acetate filter, before testing for brix, acidity and total
polyphenol using the above method.
Juice concentrate (70 brix) samples from the processing plant, and
commercial “bittersweet” concentrates were diluted an additional 10 fold by
volume before testing for total polyphenol content using the method above.
Analysis results are shown in the tables below.

nil SO2
Diameter Av weight Brix Polyphenol
Cultivar
(mm) (g)
(refrac 20 deg
C) (mg/L)
Bulmers Norman 16 2.6 7.8 13800
Somerset Redstreak 20 3.3 8.4 12000
Kingston Black (large) 28 7.9 9.3 4500
Kingston Black (small) 23 5.6 9.0 6100
Yarlington Mill 21 4.1 7.1 16000
Michelin
18 2.5 8.1 14300
Sundowner (large) 28 11.2 9.1 8600
Sundowner (small) 19 4.3 8.4 7800
Jonagold (large) 28 12.1 10.3 5300
Jonagold (small) 22 7.0 9.9 6100
Fuji (large) 29 12.2 9.2 4600
Fuji (small) 22 6.2 9.0 4700
Pink Lady (large) 28 11.2 8.9 7100
Pink Lady (small) 24 7.4 8.2 6600
Bramley (large) 27 10.1 8.1 7400
Bramley (small) 43 43.4 8.5 8300
Table 1. Apple polyphenol, diameter, weight, brix vs Variety - 20 November 2007. No sulphite used in extraction /
analysis. Lab scale.

nil SO2 +SO2
Diameter Av weight Brix Polyphenol Polyphenol
Cultivar
(mm) (g)
(refrac 20 deg
C) (mg/L) (mg/L)
Bulmers Norman 32 27.5 8.6 8000
Somerset Redstreak 39 21.4 7.8 6300 9700
Yarlington Mill 36 20.0 10.4 7700 12000
Michelin
27 10.2 10.8 4800 11100
Stoke Red 25 7.2 6.8 11200
Sundowner 36 19.7 7.1 3100
Jonagold
50 52.2 9.9 2200
Pink Lady 42 32.4 7.6 1900
Bramley
67 113.0 7.1 3600
Hillierii (crab apple) 11 1.0 8.9 19500
Golden Hornet (crab
apple) 17 2.2 8.8 15500
Aldenhamensis (crab
apple) 16 2.3 7.5 10400
Table 2. Apple polyphenol, diameter, weight, brix vs Variety - 20 December 2007. Lab scale.

Lab scale samples Plant scale
nil SO2 +SO2 +SO2 +SO2
pressed juice filtered juice concentrate
polyphenol Brix polyphenol Brix polyphenol Brix polyphenol Brix
Processing date mg/L (refrac) mg/L (refrac) mg/L (refrac) mg/L (refrac)
6 December 2007 3400 7.5 6900 6.8 7000 6.5 91000 69.8
13 December 2007 2500 7.7 6800 7.6 6700 6.8 89000 69.8
21 December 2007 9.0
6 - 8 January 2008 4300 5.2
87000 70.7
Table 3. Plant process data for immature apple thinings.
Note that additional water was added to the milling process for 6-8 January processing to improve pumpability. This
reduced polyphenol and brix by dilution. The additional water was removed at evaporation to produce similar concentrate
results to previous pressings.
Miscellaneous results on concentrates - all circa 70 brix
polyphenol
mg/L
UK bittersweet concentrate 2007 sample 1 18600
UK bittersweet concentrate 2007 sample 2 15500
UK bittersweet concentrate 2004 sample 17900
French bittersweet concentrate 2007 sample 8700
French bittersweet concentrate 2008 sample 11300
Tasmanian culinary apple juice concentrate early 2007 4900
Tasmanian culinary apple juice concentrate late 2007 3500
Table 4. Analyses of commercial apple concentrate samples.

Fig 9. Photograph of immature apple thinnings.
Fig 10. Photograph of mature table fruit, same scale as Fig 9.

Cider samples were then prepared on a pilot scale using traditional
European bittersweet concentrates, or alternatively immature apple extract
concentrate. After a number of iterations, cider formulations were achieved that
gave a good product match, and these were then produced on a commercial
scale. The match was verified using triangular taste testing. Taste evaluation of
bitterness / astringency as well as analysis of total polyphenols in the finished
cider also confirmed a good match.
Discussion and summary
Analysis of the results achieved confirms the significant impact that SO2
has in extraction and yield of polyphenol (Table 2 and 3). Ascorbate was also
trialed (not reported here) and found to be effective but less so. In the final
decision, SO2 was used as it is already employed in the usual processing of
apples for manufacture of cider, and of processing grapes for wine.
Similar trends were observed in relation to cultivar and fruit development
as were reported by Martin, although this work (Table 1) indicates that fruit
maturity as measured by duration from fruit set is probably a better measure of
potential polyphenol concentration than fruit size alone. It appears that under
Tasmanian conditions a cut off around mid December would be a suitable
compromise between decreasing polyphenol concentration and absolute yield
due to increasing fruit size.
While it was established that cultivar has a major impact on polyphenol
level, the plant scale trials used fruit of undefined cultivar. The most common
cultivars produced by the growers supplying immature fruit thinnings are Fuji,
Jonagold, Pink Lady, Red Delicious, Gala and Golden Delicious. Although a
range of other table cultivars are also grown, it is probably reasonable to surmise
that a majority of thinnings derived from these 6 most common cultivars.
Fruit was hydrocooled before cold storage as it was observed that without
this step the fruitlets would heat up and possibly begin to “compost” due to a
combination of trapped field heat and poor air circulation due to the small fruitlet
size.
The trend of initial high polyphenol concentration which declined with fruit
development was observed across all cultivars examined, whether table,
culinary, bittersweet or crab apples. Crab apples would appear to have the
greatest potential for polyphenol extraction, if orchards were to be planted with
this as the only aim.
The level of total polyphenol achieved in immature apple concentrate of
90000 milligrams/litre was approximately 6 times the typical level found in
commercial “bittersweet” concentrates which demonstrated levels around 15000
mg/l. Immature apple concentrate contained approximately 20-25 times the
levels demonstrated in culinary apple concentrate.
The immature apple concentrate was used to produce commercial ciders
that were product matched to ciders produced using traditional bittersweet apple
concentrates.
Further fruit thinnings have been processed in the 2 years since the 2007 /
2008 trial, with similar results achieved. This has demonstrated that immature

apple concentrate is a reliable, available alternative to imported bittersweet
concentrates, which have at times been in very short supply. Cost analysis (not
detailed here), at present 2010 commodity prices for apple concentrates, is
favourable towards formulations using immature apple extracts either as a
complete or partial substitute.
Acknowledgements
We would like to thank all who assisted and supported this work and the
management of Carlton and United Breweries for the permission to publish this
paper.
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