Journal of Scientiltc & Industri al Research

Vol. 62 , June 2003, pp 60 1-608

Effect of Maturation on the Physico-chemical and Sensory Quality of Strawberry Wine

Somesh Sharma and Vinod K Jos hi *

Dcpartment of Post-harvest Technology, Dr Y S Parmar University of Hort & Forestry, Naun i, So lan (Himachal Pradesh)

Received : 07 Januarey 2002; rev. recd: 26 February 2003; accepted: 10 March 2003

Wine from strawberry (Fraga ria al/al/assa), an important temperate fruit , was prepared using three cultivars and by four different methods and matured for 9 mo . The maturation resulted in an increase in reducing sugars , total esters and volatile acidity and a decrease in total soluble soli ds, total sugars, titratable acidity, colour, anthocyanins and total phenols. All the three culti vars foll owed thi s trend in all the characteri stics except vo latile acidity. Differences in changes of different characteri stics during various intervals were also recorded. The wi nes mai ntained their ori gina l dilTerences even aner maturation . Most of these changes were similar to those observed in red grape wine and the values obtained aner maturation remained within the range normall y observed in such wines. These changes increased the palatabi lity of wine and thus , desirab le. In general, the maturation of wine improved sensory quality of strawberry wines, irrespective of the method followed and the cu lt ivar.

Keywords: Strawbwrry wine, Maturation, Physico-chemical changes, Grape wine

Introduction

Strawberry fruits are so ft , be longing to the family rosaceae, and are grown throughout the world . The fruit is bestowed with an attracti ve colour and delicate fl avour. But the fruits are highl y peri shable, charac teri sed by a very limited post-harvest life at room temperature. Preparati on of strawberry wine can be one of the a lte rnatives to utilize these fruit s. Strawberry wine of good quality has· the appealing colour of a premium rose wine. Unfortunately the attractive co lour is often short-lived, c hanging to an undes irable brown. Different methods of preparation of wine hav ing attractive colour were, therefore, attempted 1. But how the wine behaves during maturati on would largely determine its final quality.

In genera l, maturation involves severa l independent events that improve wine qualit/. During maturation of wines from grapes, a lcohols react with organic acids (tartaric, malic, succinic and lactic acids) to form esters which increases with

* Correspond ing author vkjoshi pht@ reditTmai l.com

age ll1g of wines' .The concentrati on of volati le compounds a lso increases during fe rmentati on as we ll as during storage. However, increase in vo lati Ie ac idity is not cons idered desi rab le. During age ing the ox idation of wine phenolics yie lds peroxide whi ch, in turn , oxidizes ethanol to aceta ldehyde and subsequentl y to acetic acid4

. Decrease in tannins due to complexing of tannins with prote ins and/or their polymerization results in slow smoothening of taste"'·). The changes that occur during age ing the most documented are th ose affecting co lour. During ageing of red wines , both co loured and non-co loured phenolics are reported to pl ay an important ro le and durable quality is associated with hi gh phenolic contents6

. However, lack of publi shed informat ion on the maturati on of strawberry wine prompted us to undertake the present inves ti gat ions and the results are descri bed here.

Material and Methods

Preparation of Wine

Strawberry fruits of three cvs o f strawberry i.e. camarosa, chandler and dough las were empl oyed in wine making. Culture of Saccharomyces cereviseae

602 J SCI INO RES VOL 62 JUNE 2003

var ellipsoideus stra in UCD 595 used in the study was origin a ll y obtained from the Department of Enology and V it iculture, Cali fo rni a Davis.

T he wines were prepared by different methods vi::.., carbonic macerat ion, thermovinification and fe rmented on the skin a long with the control. In a ll the cases, s trawberry pulp was diluted in I: I ra tio

ra ising initial TSS to 24 DB with suga r, adding pectinol (0.5 per cent), diammonium hydrogen phosphate (DAHP, 0.1 per cent) and potassium metabisulphite (KMS , 100 ppm), respecti ve ly. In the carbonic maceration method, be rries were kept in carboni c fe rmen tati on tank for 4 d at CO2 pressure of 15 psi and then pulp was made, whereas in the rmov inification berries were heated with 50 per

cen t wate r at 65-70 DC for 5-6 min . In ferm ented on the skill method, the berries were washed, des temmed and 50 pe r cent wa ter was added and the contents were placed in 5 L g lass f lask, S02, (50 ppm), DAHP (0. 1 per cent) and pect inol (0.3 per cent) were al so

added. The TSS of a ll the musts was kept at 24 DB and 5 per cent yeast (Saccharomyces cereviseae) inocul at ion of was added. After compl et ion of fermentation in all the cases, siphoning/racking and filtrati on were done. During maturation the willes were analysed every 3 months, up to 9 months .

Analysis

Wines were ana lysed for vari ous physico­chemica l c haracteristics. The TSS was measured

using Erma hand refractomete r (0-32 DB). Tota l and reduc ing sugars, tit ratable ac idity were measured by Lane and Eynons vo lumetric method7 Ac id was measured by the titrat ion and ex pressed as per cent

c itric acid. Lovibond Tintometer model E was used to measure the co lour of wine samples us ing I in celis. E thy l a lcoho l in the finished wine was dete rmined by the spectrophotome tric method9

. Vol atil e acidity was estimated by the standard method' . T ota l pheno ls were est imated by Folin-Ciocalteau procedure 10 .

Tota l es ters were de te rmined as pe r the prescribed method" . Fusel o il was estimated by the prescribed method '2. Anthocyanin was measured by the method given by Harbone 13 In sensory analysis, numeri cal scoring of different wine was conducted initi a ll y and arIel' 9 mo o r maturation . Samples in the coded form were presented to the j udges in separate booth s on the

prescribed pro-forma' .

Stalistical Analyses

Data on variou s phys ico-chemical chara­cteristics of wines were analysed by CRD des ign as pe r the methods outlined 14 by tak ing three

repl ications of eac h treatment. In sensory analys is, there were 10 j udges w ho parti c ipated in sensory eva luati on. The data of sensory analys is were analysed by the RBD i.'.

Results and Discussion

Physico-chemical Characteristics

During maturati on TSS decreased significantly in a ll the culti va rs and the trea tments, but the de rease was not appreciable. Intere , ting ly, both the treatments and cultivars maintain ed the ir initi a l d iffe rences even after maturat ion. A mong the cu lt ivars (Table I), wine from Chand le r cu lti va r was found at pa r during 6 and 9 months interv:.l l, whereas among treatme nts wi nes (Figure I) fe rmen ted on the ski n were found at par at 6 and 9 months in te rva l. Prec ipitation of soluble so lids du e to interacti on of various components during maturati on mi ght have caused a decrease o f TSS ' 6 Simi lar to the TSS, a decrease in total sugars was a iso observed among the diffe rent treatments (Figure I) . T he decrease in tota l sugar mjght be the result of poJyphenol ox idase act ivity which catalyzes enzy matic browning by Mailla rd 's reacti on, resulting in non-enzymatic browning. As expected , the re was a s igni fica nt increase in reducing sugars in different wines during maturation . The inc rease in reducing sugars of wines of diffe rent cultivars (Tabl e \) and treatments was a lso observed during maturati on (Figure I) . T he inc reasing trend of reduc ing sugar is appa rentl y the result of hydro lys is of tota i sugars into reducing sugars, during maturati on'. It is s igni f icant from the tas te quality of wines thus, des irab le.

It is a lso disce rn ible from the da ta (Tab le I) that during advancement of matu rati on, titratab le acid ity decreased s ignificantly. The highes t ac idity before and afte r maturation was recorded in the rmov ini f ied wines (Figure 2). T he decrease in ac idity in wines during maturation in abso lute te rms was however, not appreciable, which might have occurred by the precipitati on of differe nt ac ids in the fo rm of the ir respec tive sa lts' . It is des irable ill \v ines from ac id ic fruits as it increases palatabili ty'6. These observa tions

Table I

Table I-Changes in Physico-Chemical charactersti cs of stra\Vb~lTy during maturati on

Charactersti cs Call1 arosa Chandler

Mo MJ M2 MJ Mo MI M2 M3 Mo

Total so luble so lids, °8 9.8 9.7 9.6 9.6 8.2 8.0 8.0 8.3 9. 1

Total sugars, per cent 1.90 1.80 1.60 1.40 0.73 0.72 0.56 0.49 1.00

Reducing sugars, per cent 0.08 0.132 0.155 0.167 0.072 0. 122 0.147 0. 153 0.08 1

Titratable ac idity, per cent 0.69 0.66 0.63 0.62 0.74 0.73 0.72 0.7 1 0 .67

pH 3.13 3. 18 3.20 3.22 3. 19 3. 18 3,23 3.25 3. IS

Ethanol, per cent 11.1 11 .1 I 1.1 11.1 11.4 11 .5 11 .5 11 .5 9.3

Hi gher alcohol, mglL 163 155 15 1 149 189 173 164 157 157

Volatile acidity, per cent AlA 0.023 0.025 0.027 .032 .028 .03 1 .034 .038 0 .023

Esters, mglL 60 78 97 130 45 67 89 III 62

Phenols, mg/L 158 148 139 133 143 132 125 11 8 149

Anthocyanins, OD/mL 0.192 0. 153 0. 133 0. 123 0 .176 0.155 0. 136 0.1 15 0. 11 2

Colour units, red 15 17 13 15 12 II 10 10 12

yellow 15 23 17 14 25 20 16 15 22

Storage interva l-Mo. initial , M 1. aft er 3 month , M2, after 6 month , MJ. after 9 month

Doughlas

MI M2

8.9 8.7

1.00 0.96

0. 124 0.147

0.67 0.63

3.25 3.29

9.2 9.2

150 147

0.028 0.025

84 11 8

143 130

0. 110 0.099

15 8

17 10

CD (P :5 005 )

M3

8.6 0 .06

0.86 0 .05

0. 159 0.004

0 .62 0 .04 1

3.35 0.023

9.2 NS

148 0.S85

0.025 0.008

146 0.954

11 9 4.83

0.087 0.D3 1

4 1.36

9 1.08

CI: :r: ;» ;:0

$: ;» R? '-0 C/)

:r:

-c :r: -< C/)

n 0 n :r: tTl $: n ;» r R? C/)

tTl Z C/)

0 ;:0

-< 0 c ;» r =i -< 0 'Tl C/)

-l ;:0 ;» < co tTl ;:0 ;:0

-< < Z tTl

0\ o w

604 J SCI IND RES VOL 62 JUNE 2003

-+- Conlrol ____ Thermo-..(nificatlon

10.5 --b- Carbonic maceration -N- Fermented on sktn

10 CO(O·05)·l

9.5 r------'--

IJ)

~ 8 .5

8

7 .5

7

o 3 6 9

Duration (rronths) .

1.8

1.6 CO(O.OS)- ]

1.4 ~ 1.2 III ... 1 "' Ol :> 0.8 III

"' 0.6 0 I- OA

0.2

0

0 3 6 9

D.Jration (months)

0.18 CO(0.05)-

0.16 ~ ..,

0.14 ... "' Ol :> 0.12 III

Ol C u 0. 1 :J

"0 ClI

O.OB CC

0.06

0 3 6 9

D.Jration (months)

Figure I - Changes in total soluble solids (oB), tolal sugars and reducing sugars (%) during malurati on of differenllrealmenl s

slrawberry wine

were corroborated by changes in pH (Table I and F igure 2) where in pH of d ifferent wines increased. Further, the trend of increasing pH with maturation in al l the wines was observed. There were significant differences during maturation be tween wines of different treatments and cuiLivars . However, wines

0.6

0.75

C .~ 0.7 '0

'u 0.65 " " 1i

!I 0.6 " b i= 0.55

0.5

0

3.28

3.26

3.24

3.22

:r 3.2

-+- Contlol -c:r- C~ rbonlc m ~ce r-I lJon

___ ·ihCtmO-.1nII'lCllJon

---H- Fermented on 'kIn

co;o D:'J-

3 6 Du,.Uon (montn»

CD{O 05)" I

c.. 3.1B

3.16

3.14

3.12

3.1

0 3 6 Duration (month s)

Figure 2 - Changes in lilrablc ac idity and pH during maluralion of dilTerenll reatmcnts st rawberry wine

9

9

from Doughlas cultivar were at par afte r 3 months maturation , whereas among the trea tments, wines made by normal fermentation and that fermented on the skin were initially at par and thermovinifi ed wines were at par wi th carbonic macerated wines, during 6 and 9 month s of storage. The wines maint:1ined the ir initia l diffe rences during and after matu ration and these changes could be corre lated with the prec ipitation of acids as sa lts, as di scussed earlier.

Data presented in Table I show that e thanol content of wines did not decrease s ignificantl y during storage. Also the differences were too smal l to be appreciable in the tre nd of c hanges in w ine o f d ifferent treatments, as shown in F igure 3. The s light decrease in ethano l might be due to the reac tion of alcohol with acids to form este rs ' ,4

SHARMA & JOSHI: PHYSICO-CHEMICAL & SENSORY QUALITY OF STRA WBERRY WINE 605

-.-Conlrol - __ Thelm oVlm fl c allon

-0- CarboniC mac eratlon -w-Fermented on skm 10 .9

10 .8

10 7 :::::=--

~J l0 6 .~--"> 10 .5 :: "0 10 .4 c

10 .3 .. 6 UJ 10 .2 ~

10 .1

10

9 .9

o 3 9 Duration (monlhs)

175

170 COlO 05),1

::::: 165 Cl

E Y 160 0 r. 155 0 u

"' 150 ... 41 r. 145 Cl

J: 140

135

0 3 6 9

Duration (m onths I

0.034

~ 0.032

0.03 ~ .~ 0.028 "C COlO 05)' I u 0.026 "' ~

co: 0.024 !!! 0 > 0 .022

0.02

0 3 6 9

. [).Jratlon (m onths I

Figure:l - Changes in ethano l, hi gher a lcohol and volalile acidity during maturati on of different treatments

strawberry wine

Results (Table I) show that during maturation hi gher alcohols decreased significantly. Cultivar Chandler had the highest fusel alcohol initially and remained on the s imilar lines even after maturation . In other treatments also the trend remained the same, i.e. hi ghes t in control and lowest in wine from the

must fermented on the skin. The trend of c hanges of ethanol in different wines due to treatments given is shown in Figure 3, which shows significant differences during maturation . The amount of higher alcohols in the table wines varied from 140-420 mglL and in dessert wines from 160-900 mg/L.1 . Red wines contained slight ly more of the higher alcohols than white wine 17

. Since in these wines higher alcohol s are in the range described above, it indi cates proper storage conditions (non-oxidative conditions) during maturation of strawberry wine were maintained, as recommended' 8. A decrease was recorded in fu sel alcohol of different cultivars and treatment wines . Fusel oil formation is the result of transamination of corresponding amino acids due to which initially there were more alcohols, but with maturation these were used for ester formation , he nce the ir decrease took place4

. Loss of higher alcohols to form esters is favourable to desirable sensory properties of wines. Volatile acidity also increased s ignificantly during maturation . The vaneties behaved differently registering either a decrease or increase. Initially the highest volatile acidity was recorded in Chandler and it was similar after maturation . The wines made from different treatments a lso regi stered enhancement of volatile acid due to ageing. However the volatile acidity in strawberry wines was 0.024-0.0:n per cent, indicating their soundness. The trend of volatile acids during maturation is shown in Figure 3. The legal limit for volatile acidity in different wines is 0.12 per cent for red wines and 0.1 I per cent for the other wines', and wines of all the treatments and cultivars fell within the range. The probable reason for increase in volatile acidity of wines could be the oxidation of phenolics to yield peroxide which in turn might have oxidized ethanol to acetaldehyde and subsequently to acetic acid''!. Moreove r the volatile acid content of less than 0.070 giL seldom imparts any spoilage character to the wine but in combinati on with low concentration of e thyl acetate may contribute to overall wine complexit/ .

Total esters in wines of all the three cultivars and treatments during maturation increased (Tabl e I) but maintained initial trend and the ir interac tions were also significant (Figure 4). Increase esters during maturati on IS attri buted phenomenon of age ing' , that is desirable deve lopment of prope r fl avour. The amount

in total to the for the of total

606 J SCI INO RES VOL 62 JUNE 2003

-+-- Co ntrol ___ Thermo,;n iflcatl on -.o- Ca,boni c ma c eration __ Fermented on sk in

170

160 CO(0 05)- I

0. 150 .S-III 140 0 c II

130 .<: Q.

~ 0 ~

120

11 0

100 0 3 6

Du ration (months) 9

140.------------------------------. 130 120

110 '§, 100

I 90 III

~ 80 VI

w 70

60

CD(005)=I

50 40+---------.---------.---------~

o 3 6 9 Ouralion (months)

0.2 -.-------------------------------,

~ 0.18 .~ O. 16 f:""---__ ~

:§ 0.14 o Q. 0.12

.~ 0. 1 .. if 0.08 o ;:; 0.00 C ~ 0.04

CD(o.OS)-l

0.02 +-----------.------------,.---------j o 3 6 9

D.lration (months)

Figure. 4 - Changes in phenol, esters and anthocyanins durin g maturation of different treatments strawberry wine

es te rs in vari ous wines as summari zed2o

, varied be tween 200 to 400 mg/L. Genera lly , es te rs have f rui ty and fl ora l impact, important in sensory properties o f wine. In addition to the este rs contri buted by fruit , esters are a lso fo rmed as a resu lt of reacti on between acetate and ethanol as we ll as

other hi ghe r alcoho ls or from ethanol by reaction with straight chain fa tty ac id precursor 4 , Increase in esters is perhaps the most des irable aspect of maturati on as it increases aroma and fl avour notes of wines and hence, its acceptability.

Another s ignificant effec t of matu rati on was the dec rease in tota l pheno ls in wines of diffe rent treatments and cultivars. Among the treatments (Figure 4), there were s igni fica nt d iffe rences during storage, but the trend observed in iti a ll y re mai ned afte r maturation a lso. Reducti on in tota l pheno ls might be due to the ir suscepti bility to degradation, condensati on and polymeri zat ion , and subsequent prec ipitati on4

.2

1.22. T he results migh t be ' igni ficant in increas ing the palatability of the wine . Li ke pheno ls, anthocyanins in wines a lso s igni ficantly dec reased during maturati on (Table I ). The anthocyanins gecreased in a ll the culti va r wines. However, in matured wines the diffe rences present ini tia ll y in d iffe rent culti va rs or in the wines of diffe rent treatments were maintained. The contro l wille recorded the highes t levels of anthocyan i Il S before and after maturation. But wines fro m C hand ler and Doughlas were at par during 6 and 9 months of storage. Among the treatme nts (Figure 4), wines made by carboni c maceration thermov ini ficati on and fe rmented on the skin were at par during 6 and 9 months o f inte rva l. Degradati on and po lymeri zati on of anthocyanins with time might be the contributor to thi s e ffect as anthocyanins the red pigments, has been reported in raspberry and other fru its 23 Up to 50 per cent loss of anthocyan in s has a lso been reported a ft e r

. 14 agelllg-

The red tintometer colour units (red and ye ll ow) in wine during maturati on increased wh il e ye llow decreased up to 6 months o f storage afte r which the red colour units a lso decreased (Figure 5). Anthocyanin compos ition and content , and cu lti var maturity were found to influence the co lour of red

. 25 A . wille. S agell1g progresses, colour becomes less intense, and starts to turn bricki sh and eventua ll y becomes tawn/ 6

. In red wines, co lour changes largely refl ect the polymeri zati on and ox idat ion of

h . 27 ant ocyamns .

Sensory Evaluation

It is di scern ib le from T ab le 2 tha t after maturation for 9 mo nths, a ll the wir,es were awarded

SHARMA & JOS HI: PHYS ICO-CHEMI CAL & SENSORY QUALITY OF STRA WBERRY WINE 607

Tabl{' 2-EfTect of matura tion on the sensory scores of vari ous attributcs of strawberry wines

Attribute Maximum score Initial score Final score CD (PS 0.05)

Colour and depth 2.0 1.29 1.20 0.024

Aroma and bouquet 4.0 3.42 3.57 0.021

Appearance 2.0 1.34 J.:l9 0.081

Volatile acid ity 2.0 1. 34 1.52 0.016

Total acidity 2.0 1.53 1.65 0.0 18

Sweetness 1.0 0.62 0.74 0.006

Body 1.0 0.64 0.72 0.006

Flavour 2.0 1.49 1.70 0.0 12

Bitterness 1.0 0.68 0.58 0,005

Astringency 1.0 0.72 0.6 1 0.005

Overall acceptability 2.0 1.64 1.72 0.005

Total sco re 20 14.7 15.4 0.079

Scale accord ing to Amerine el al. ( 1968) Ratings, superioer, 17-20; standard, 13- 16; below standard, 9- 12; unacceptable, 1-8

__ Control ____ Thermoloinifica tion

-t>- CaftJonic maceration __ Fermented on skin 18

16 COlO 05)=1

14

~ '1 2 .. ~ 10 :; 8 0 '0

6 u 4

2

0

0 3 6 Duration (m onths)

30 CO(O.OS)= I

25

~ 20 .2 Qi ?:. 15 ~

::l .2

10 0 u

5

0

0 3 6 Duration (months)

Figure 5 - Changes in colour (red and yellow) du ring InalUration of different treatmen ts strawberry wine

9

9

higher scores for each attribute except co lour than the initi al scores and the differences were signi ficant. Decrease in colour scores mi ght have occurred due to browning of wines as descri bed ear lier a ls026

. Dur ing age ing, tannin , anthocyanin and tota l sugar decreased , whereas an increase was observed in total esters, higher alcohols, reducing sugar and pH . The decrease in bitterness improved wine qua li ty. The changes have been reflected in sensory qua lity of di fferent wine samples. As the wine ages properl y the harsh taste and yeasty odour dimini sh and a smooth me ll ow fl avour and c lean odour are produced'. Thus, maturation altered various components of wine, which were des irable for the sensory quality. However, other parameters (vo latil e ac idity, titratab le ac idity, TSS , pH and reducing sugars, total sugars) virtually remained unaffec ted. To sum up the various changes in chemical characteristics rema ined withi n the limits prescribed . Further, an overview of the results also sugges ts lhat wine re mained in the sati sfactory conditi on during maturat ion and these changes were s imjl ar to those whi ch occurred fo r any red grape wine during maturation26

.

. Conclusion

T he maturation study a lte red van ous components of strawberry wine like, es ters, phenols, hi gher alcohols whic h are des irab le fo r wine quality.

608 J SCIIND RES VOL 62 JU NE 2003

Other parameters like volatile acidity, titratable acidity , TSS, pH, and reducing sugars , total sugars virtually remained unaffected. Changes in physico­chemi cal characteri stics have been reflected in the senso ry scores al so. The maturation period of 9 month definite ly improved quality of strawberry wines produced differently.

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