Describe the preparation of jelly. Explain the theory of jelly formation.

1. 1 · Open in two lines. Jelly is a clear, sparkling, semi-solid product made by boiling strained fruit extract with sugar and acid until it sets. Guava jelly is the Indian favourite.
2. 2 · Theory: the pectin-acid-sugar balance.
   • Pectin (0.5-1%) forms a network of long chains.
   • Acid (pH about 3.0-3.3) neutralises pectin's charge so the chains meet.
   • Sugar (60-65%) pulls water off the chains so they bond and trap syrup.
3. 3 · Draw the gel network. [Sketch: pectin chains joined at junction points, with sugar syrup held in the spaces]
4. 4 · Steps.
   • Select firm-ripe, pectin-rich fruit; slice and boil with water.
   • Strain through a muslin bag without squeezing.
   • Alcohol test for pectin; add sugar accordingly, and acid if needed.
   • Boil rapidly; skim off scum.
5. 5 · End point. Sheet test, drop test, about 105 °C, or refractometer reading of about 65% TSS.
6. 6 · Fill, seal and note defects. Pour hot into sterile jars and seal with wax. Defects: no set, cloudiness, weeping, crystals, mould.
7. 7 · Nutrition link. Mostly sugar; use sparingly in diabetic diets; most vitamin C is lost in boiling.
8. 8 · Close in one line. A good jelly depends on the right pectin-acid-sugar balance and the correct end point.

Scoring tip: Draw the pectin network and give the three numbers (pectin, sugar, pH); they carry the theory marks.