THE STABILITY OF STRAWBERRY JAM DURING STORAGE

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THE STABILITY OF STRAWBERRY JAM DURING STORAGE

• Group Members
• Selim YILDIZ 060010231
• Onur GÖKKURT 060020801
• Seçil ILERI 060000406
• Zeycan Asu AKBAS 060990407

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THE STABILITY OF STRAWBERRY JAM DURING STORAGE

• Traditional jams, made almost entirely from fruit
  and sucrose, are boiled or evaporated down to
  0.75 aw. They very rarely spoil. To produce jams
  which will not spoil, the water content of the
  product must be reduced to a safe aw.
• Commercially prepared products aw is often
  closer to 0.80-0.82. At this aw they are much
  more likely to support mould growth.

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• The final soluble solids (SS) content (mostly
  sucrose, fructose and glucose) of conventional
  fruit preserves is 68-70. This level of SS is
  required for gel formation and to prevent mould
  growth during storage.

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strawberry jam

• The pH value 3.0 - 3.3
• Soluble solids 68 - 72
• Water activity 0.80 0.82

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Factors Affect The Shelf Life of Strawberry Jam

• Microorganism Activities
• Only osmophilic yeasts and xerophilic molds can
  cause spoilage. If jams spoil, Eurotium species,
  Aspergillus restrictus and xerophilic Penicillia,
  especially P. corylophilum are usually
  responsible. The black yeast-like fungus
  Trichosporonoides nigrescens has also been
  reported from spoiled, fermented jam.

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Factors Affect The Shelf Life of Strawberry Jam

• Crystallization
• Crystallization of sucrose in jams with SS
  values above 65 can occur in cold
  weather/domestic refrigirator storage. Such
  crystallization is rare in products containing
  less than 68 solids.

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Factors Affect The Shelf Life of Strawberry Jam

• Browning Reactions
• Loss of color during storage appears to be due
  mainly to browning reactions. This browning
  includes Maillard and enzymatic browning
  reactions, but appears to be mainly due to
  polymerization of reactive phenolics,
  leucoanthocyanins and catechins.

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Factors Affect The Shelf Life of Strawberry Jam

• Syneresis
• Too much acidity results in syneresis (water
  elimination) during storage which is undesired.
• Other factors
• The Initial Microflora
• Physical and Chemical Properties of Product
• Processing Technique
• Packaging and Storage Conditions

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• Strawberry jams are almost stable foods. The
  most important consideration of strawberry jam is
  color degradation. Loss of red color is
  influenced by Maillard and enzymatic browning,
  ascorbic acid degradation and polymerisation of
  anthocyanins with other phenolics.

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• Other factors affecting color include fruit
  pH and acidity, storage temperature and fruit
  cultivar. The main anthocyanin responsible for
  strawberry color is pelargonidin 3-glucoside.
• Anthocyanins Abroad and important group of
  blue, water soluble pigments.

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• In this study, the objective was to determine the
  stability of three strawberry cultivars (
  Chandler, Tudla and Oso Grande). Jams were
  then stored at 20, 30 or 37C in the dark, for
  200 days.
• Shelf-life statistical analysis
• Based on correlations between shelf-life and
  color, the shelf-life for each jam was evaluated
  according to the Arrenhius equation. The
  expression describing change in quality attribute
  a in a non linear form for a first order
  reaction is

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• a a0 .exp -k0 . t . exp( -Ea/R . T)
• where aCIE a parameter
• a0 CIE a parameter at time 0
• k0 pre-exponential factor (1/day )
• ttime (days)
• Ea activation energy (cal/mol)
• Rgas constant (1.987 cal/K.mol)
• T temperature (K).

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• RESULTS
• Changes in titratable acidity, total soluble
  solids (TSS) and pH
• No changes in titratable acidity were observed
  during storage at 20, 30 and 37C. In addition,
  the TSS showed a constant value (lt65 Brix,
  SD60.5) for all samples.

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• Cultivar differences in anthocyanin during
  processing
• Oso Grande had the lowest concentration of
  tolal anthocyanins while Chandler had the higher
  concentration and Tudla was intermediate. Oso
  Grande had the highest anthocyanin degradation
  during processing.

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• Effect of storage temperatures on anthocyanin
  stability
• Anthocyanin is more stable at the lower
  temperatures. No differences were found in
  degradation kinetics of anthocyanins between
  cultivars at the same temperature. Storage
  temperature was a more significant factor than cv
  for anthocyanin loss during storage. All the
  cultivars exhibited a very fast decrease when
  stored at higher temperature (37C) and much
  slower at 20C.

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• Effects of storage temperature on color
• Comparing results at 20C, the 3 CVs did not
  show significant differences in slope (indicating
  the same degradation kinetics).
• The shelf life, based on changes in color,
  was calculated mathematically for each jam and
  results showed that jams would be acceptable for
  over 400 days only if stored at 20C and prepared
  with Chandler or Tudla cultivars. A much shorter
  shelf life would be found for those products
  prepared with Oso Grande (230 days).

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• DISCUSSION
• Monomeric pigment concentrations decrease during
  storage.
• The stability of anthocyanins was markedly
  influenced by temperature.
• The expression of anthocyanin color is pH
  dependent.
• The rate of color loss was slower than the rate
  of anthocyanin degradation.

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• DISCUSSION
• Daylight conditions caused insignificant colour
  and anthocyanin losses, compared with jams stored
  in total darkness.
• Comparable color during storage is more likely to
  be due to polymerization phenomena mediated by
  flavon 3-ols.
• General browning is influenced by Polyphenol
  Oxidase.

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• CONCLUSIONS
• Oso Grande jam had the lowest anthocyanin
  concentration, higher monomeric pigment
  degradation during processing and storage,
  highest pH, least acceptable color and shortest
  shelf life.
• Jams prepared with Tudla or Chandler cultivars
  had almost similar properties.

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Color Stability of Strawberry Jam as Affected by
Cultivar and Storage Temperature

• Table 1-Shelf-Iife (days) of jams prepared with
  different strawberry cultivars, stored at
  different temperatures
• aChandler a 40.36exp1.982108texp(-7537.32/
  T) R20.8736
• bTudla a 40.77exp8.327108texp(-7950.15/T)
  R20.9524
• cOso Grande a 33.84exp3.142107texp(-6929.0
  1/T) R20.9251

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• References
• David, K., Subramaniam, P., 2000. The Stability
  and Shelf Life of Foods. Woodhead Publishing and
  CRC Press, Cambridge, England.
• Eskin, N.A.M., Robinson, D.S., 2001. Food Shelf
  Life Stability. CRC Press.
• Fellows, P., Battcock, M., Judge, E., Ali, A.,
  2003. Small-Scale Food Processing. ITDG
  Publishing, Great Britain.
• Garcia-Viguera,-C Zafrilla,-P Romero,-F
  Abellan,-P Artes,-F Tomas-Barberan,-F-A, 1999.
  Color Stability of Strawberry Jam as Affected by
  Cultivar and Storage Temperature. Journal of Food
  Science, 64(2) 243-247.
• Garcia-Viguera,-C Zafrilla,-P
  Tomas-Barberan,-F-A, 1999. Influence of
  Processing and Storage Conditions in Strawberry
  Jam Color. Food Science and Technology
  International, 5(6) 487-492.

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