Test Method for Pectin Strength

Test Method for Pectin Strength

Pectin is a natural polysaccharide that primarily exists in plant cell walls, and is particularly abundant in citrus peels and apple pomace. It usually appears as a white to yellowish-brown powder, odorless, tasteless, and with a slippery texture. In the food industry, pectin is commonly used as a thickener and gelling agent, for example, in the production of jams, jellies and gummy candies. It is stable in acidic environments, but will hydrolyze when heated for an extended period under high-temperature and acidic conditions. Pectin has strong gelling power, and unlike other gelling agents such as gelatin, it cannot be replaced arbitrarily. In addition, pectin is a water-soluble dietary fiber that is beneficial to human health.

Experimental Objectives：

Master the Determination Principle: Understand how the strength of gel foods such as jams and jellies is scientifically measured through the experiment, including the mechanical principles and influencing factors behind it.

Understand the Influencing Factors: The experiment will help you comprehend which conditions (such as temperature, acidity, sugar concentration, etc.) affect the strength of the final gel, thereby providing a basis for actual production or formula adjustment.

Experimental Samples and Instruments：

Experimental Sample: Pectin

Experimental Instruments: ST207 Pectin Strength Tester (SAG Method), compliant with QB2484

Experimental Procedures

1. Instrument Preparation

Jelly Strength Tester Configuration: Equipped with a micrometer screw (32 threads per 2.5 cm, moving 0.0792 cm per full rotation), a standard glass cup (Hazel-Atlas No.85, inner height 7.94 cm, total height 9.94 cm with metal frame), a glass plate, a stopwatch, and a metal cutter.

Instrument Calibration: Place a standard rod (with known height) vertically on the glass plate and position it under the micrometer screw.

Rotate the micrometer screw so that its tip just touches the surface of the standard rod, and record the reading (which should be 20.0). If it does not match, adjust the fixing screw of the vertical scale until the standard value is reached.

2. Strength Determination

Placing the Gel: Place the truncated conical gel on the glass plate of the instrument base, aligning its center with the tip of the micrometer screw.

Measuring the Depression Depth: Rotate the micrometer screw so that its tip just touches the gel surface, and record the initial reading; continue rotating the screw until the tip depresses into the gel surface, and record the depression depth (unit: depression percentage, 1% depression = 0.0792 cm); repeat the measurement twice and calculate the average value.

Experimental Results：

The strength of the sample pectin is 1.57% depression units, which meets the gelling property requirements of high-methoxyl pectin.