Experiment 1 Pectin.docx

EXPERIMENT 1: DETERMINATION OF JELLY GRADE OF PECTIN BY MAKING TEST JELLIES Introduction: Pectin is a type of structural fiber found in the primary cell wall and intracellular layer of plant cells mainly in fruit such as apples, oranges and lemon. The grade of a pectin is obtained from the ratio of sugar to pectin in a jelly of standard strength. Jelly grade of pectin is the number of grams of sugar, which 1 grams of pectin requires to make a jelly of 65° Brix with a pH 3.00 ± 0.05 and other optimum conditions. Pectin which has been thoroughly mixed with 10 times its weight of sugar will readily go into solution in hot water, forming a nearly clear solution. Most commercial pectin contain dextrose to facilitate dispersion in solution. The pectin of commerce are characterized by a high content of galacturonic acid, and this has become part of the legal definition for pectin used as food additives or for pharmaceutical purposes. Typical requirement are for a minimum of 65% of galacturonic acid on the ash and moisture-free substances. Adding pectin when making jam or jelly can shortens or eliminates the cooking time, resulting in a fresher fruit flavor. Objective: 1. To understand the role of pectin 2. To determine the jelly grade of pectin to produce a good quality jelly product Equipment: Hot plate, analytical balance, top leading balance, pH meter, thermometer, hand-held refractometer, measuring cylinder (250ml), spoon, glass rod, plastic cup, beaker, and rubber band. Ingredients: Jelly grade 100 110 120 130 140 150 160 170 180 190 200

Weight of pectin (gram) 2.500 2.275 2.085 1.925 1.785 1.665 1.560 1.470 1.390 1.315 1.250

Fine sugar (250 g) Citric acid solution (50 g made up 100 ml) Sodium citrate solution (25 g made up to 100 ml)

Procedure: 1. The empty beaker with spoon or glass rod, W1 was weight. 2. 160 ml of water was added followed by 2 ml of citric acid solution and 0.5 ml sodium citrate solution. 3. The beaker was heated using hot plate at about 102°C. 4. 250 g of sugar and 1.785 g of pectin was weight (assuming to be of jelly grade 140). From the weighed sugar, weight out 17.85 g of sugar and mix with pectin (10 times the weight of pectin). 5. The beaker from hot plate was removed and the pectin-sugar mixture was dump into the beaker and the sugar and pectin was mix intimately until dissolved thoroughly. 6. The beaker was put on the hot plate and the remaining sugar was added to the solution. All the sugar was stir until dissolved and heating to boil. The beaker was removed and test weighing, W2 (weight of beaker + spoon + jelly) was make. 7. The boiling process was continued until the final weight of jelly formed is 375 g (W2-W1). 8. The beaker was removed from hot plate and let it cool for 1 minute. The foam was removed from the surface by using a spoon. 9. The hot jelly was pour into the cups and mix the content by means of a glass rod. The cups was covers with paper and allowed to stand for 18 to 24 hours. 10. Jellies of different grades was prepared as above by different batches. 11. The jellies was removed from jelly cups and placed on different plates after 18 or 24 hours. 12. The jellies was cut with knife and test for the characteristic quality of a good jelly. Requirement of good jelly a) The cut jellies should have sharp edges b) Jelly should not stick to the knife upon cutting c) Jelly should be firm and quiver when shake d) Jelly should have optimum tenderness

Results: Jelly grade

Picture

Observation

 Have sharp edges  Not stick to knife 100

 Firm but not quiver  Very tender

 Have sharp edges  Not stick to knife 110

 Firm but not quiver  Very tender

 Have sharp edges  Not stick to knife 120

 Firm but less quiver  A bit tender

 No sharp edges  Stick to knife  Not firm and not quiver 130

 Very tender

 Have sharp edges  Less stick to knife  Firm and quiver 140

 Less tender

 Have sharp edges 150

 Not stick to knife  Firm and quiver  Smooth tender

 Have sharp edges 160

 Do not stick to knife  Not firm and quiver  Too tender

 No sharp edges 170

 Stick to knife  Not firm and quiver  Too tender

 No sharp edges 180

 Stick little to knife  Not firm and quiver  Less tender

 No sharp edges 190

 Stick to knife  Not firm and quiver  Very tender

 Have sharp edges  Stick to knife 200

 Firm and less quiver  Less tender

Discussions: In this experiment, we need to determine of jelly grade of pectin by making test jellies. We also need to understand the role of pectin. The grade value of a pectin refers to the weight of sugar that one unit weight of pectin will gel. We need to make different jelly grade using different weight of pectin follow the ingredients that was given. After the experiment was done, we need to determine which one jelly that produce a good quality follow the requirement that was given. There are few requirement of a good jelly such as the jellies should have sharp edges when cutting, the jellies should not stick to the knife, the jellies should be firm and quiver when shake and jelly should have optimum tenderness. From the results, we decided that jelly grade -150 is the best where its follow the requirement of a good jelly. Jelly grade-150 have sharp edges, not stick to knife when cut, firm and quiver and optimum tender. We also make a research by reading a few article where is stated that the most common commercial pectin is 150-grade pectin, meaning that with water, sugar to give 65% solids, and acid to give the optimum pH, one unit weight of pectin will give a perfect jelly with 150 times that same weight of sugar. Pectin of 100 grade is also popular. Most jelly grade have sharp edges except jelly grade-130, 170,180, and 190. Then, jelly grade130, 170, 180, 190 and 200 is stick to the knife when we cutting and the rest is not stick. Most the jelly grade not firm and quiver except for jelly grade-150. Next, for tenderness only some jelly grade was too tender and a few jelly grade less tender such as jelly grade-180, and 200. In this experiment, we adding citric acid in the process to gives better control of the pH and minimizes pre-gelling of the batch and hydrolysis of pectin. Boiling process is one of the most important steps in jelly making. Its principle purpose is to increase the concentration of the sugar to the point where gelling will occur. The boiling process should not be prolonged because of the resultant loss of color to the product. We also need removed coagulated material and should be stirred to insure thorough mixing and uniform heating.

Conclusions: In the nutshell, jelly grade -150 is the best where its follow the requirement of a good jelly. Jelly grade-150 have sharp edges, not stick to knife when cut, firm and quiver and optimum tender. Common commercial pectin is 150-grade pectin that usually use in making jam in food industry.

Questions: 1. What is jelly grade of pectin? A method is given for grading pectin, which depends only on the strength adopted for standard jelly and a value for this strength is suggested based on considerable experience with pectin jellies. 2. What is the important of jelly grade? Important of jelly grade is to determine the proportions of pectin and sugar listed in the specific instructions that come with the particular pectin that use to produce a good quality jam.

3. How does your sugar and pH effect jelly grade? One unit weight of pectin will give a perfect jelly with 150 times that same weight of sugar, so sugar concentration is important to the point where gelling will occur. Gel firmness is dependent upon the jelly pH. Optimum firmness is achieved within definite pH ranges for the particular pectin utilized. 4. What is the best jelly grade? Discuss among a friends The best jelly grade is 150 with 1.665 g of pectin.

References: 1) L. Flutto, (2003) in Encyclopedia of Food Sciences and Nutrition (Second Edition). 2)

Sriamornsak, Pornsak (2003). "Chemistry of Pectin and its Pharmaceutical Uses: A Review". Silpakorn University International Journal. 3 (1–2): 206

3) W.A. Bender, (1949). ‘Grading Pectin in Sugar Jellies”. Analytical Chemistry. 21 (3), pp 408–411