Food Science Universe (FSU)

Preparation of Orange Marmalade (English)

Recipe

  • Juice Extractor
  • Pitting Spoon or Scooping Knife
  • Sharp Cutting Knife
  • Stainless Steel Kettle
  • Na2CO3
  • Pulper or Strainer
  • Muslin Cloth or Fine Pupler
  • Citric Acid
  • Pectin
  • Sugar
  • SMC Orange Oil 3720 @ 0.5 mL/Kg of the finished product

Procedure

  • Wash oranges in running water.
  • Cut into halves and extract the juice with a juice extractor. Keep the juice in a stress steel container for further processing.
  • Take peels and remove pectin-containing albedo with the help of pitting spoon or scooping knife.
  • Cut albedo portion into thin shreds and mix into the juice extracted above.
  • Save flavedo (the outer portion of peels—contains flavour sacs) for further processing as follows:
  • a. Cut the peels into thin slices or square pieces with a sharp cutting knife.
  • b. Soften the peels by boiling in water for 4 minutes or until tender and free from bitterness.
  • c. More softening can be obtained by boiling peels in 2.0% Na2CO3 solution followed by recooking for short time with a weak solution of citric acid (0.2%).
  • Take the mixed juice prepared in Step 2 above and measure its volume with a graduated mug.
  • Add an equal volume of water.
  • Cook the juice and strain through a pulper before the temperature falls below 71 °C.
  • Add albedo portion. Boil the mixture gently in an enamelled or stainless steel container till the pieces are thoroughly disintegrated (this should take about 30 minutes).
  • Filter through a fine muslin cloth or fine pulper.
  • Cooked juice should contain 0.5-1.0% pectin and 0.7% acidity as citric acid.
  • Carry out tests for pectin, acidity and sugar as follows:
  • a. Pectin: Take 60 mL 95% alcohol in a graduated cylinder, add 15 mL juice to be tested. Invert the cylinder 2-3 times to ensure thorough mixing. If reasonably large. clumps appear, juice contains enough pectin. If there are no lumps but the material flocculates or is in small lumps, the juice needs additional pectin.
  • b. Acidity: Titrate 10 mL juice with N/10 NaOH and calculate acidity as citric
  • acid. If tie acidity is less than 0.7%, adjust it by adding citric acid.
  • c. Sugar: Fill the Jel-meter with the juice by placing a finger at the lower opening of the Jel-meter. Allow the juice to flow down for 1 minute and close the lower opening again with the finger. Read the mark near the level of juice in the upper tube of the Jel-meter. Read parts of sugar to the parts of juice (usually it should be 65:35).
  • Add the required amount of sugar to the juice-peel mixture previously prepared and cook at a temperature of 104-110 °C as rapidly as possible to a jellying point.
  • The jellying point is determined by noting total soluble solids with refractometer which should be 68.5%. Also, perform the sheeting test given below:
  • Sheeting Test: Dip cool spoon into the boiling mixture and take out a spoonful of jelly from the container. Allow the jelly to drop from the spoon and note whether the jelly drops in a thin stream or a sheet. If the jelly sheets out, the jellying point has reached and as such it should be removed from the stove.
  • After the endpoint has reached, allow cooling to 70 °C. Add SMC orange oil 3720 @ 0.5 mL/kg of the finished product.
  • Stir the jelly gently and fill it into jelly glasses and tin cans. Seal top with paraffin wax and store in a cool place.
  • Examine the product for colour, flavour, texture, pH, soluble solids and undesirable characteristic, if any, after one-month storage and submit a report on its quality.

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