Confectionery and chocolate engineering

11.10.6 Technology of manufacturing pectin jellies

11.10.6.1 Preparation of high-ester pectin gels

The conditions necessary for gelation are fairly low pH and high soluble-solids concentration.

A critical temperature exists above which gelation will not take place, even though all other

conditions for gelation are fulfilled. If the temperature is reduced below this limit, gelation

commences after some time. The gelation temperature depends on the combination of pectin

type and the composition of the batch; it can, to a great extent, be varied t will by selecting an

appropriate type. It is not usually possible to melt a high-ester gel once it has solidified.

If a gel batch is stirred or poured while gelation is in progress (it may still look liquid!),

structures that have already formed may be broken. They will not reform, and the

corresponding part of the pectin will not be utilized in the final gel structure. This

phenomenon is known as per-gelation. Pre-gelation is very similar to the situation of poor

dissolution or distribution of the pectin. The results are similar: the gel is weaker than

expected, and gelation may, in severe cases, appear to be absent. The cause of failure is also

basically the same in the two cases: only part of pectin is utilized.

Two important differences between the gelation of low-ester pectin and high-ester pectin must

be mentionated. The difference between the setting and melting temperatures of low-ester

pectin gels is modest, and it is possible in many cases to remelt a low-ester gel pectin gel.

This is in contrast to the situation for the high-ester pectin gels. A low-ester pectin gel

solidifies almost immediately when the gelling conditions are reached; a high-ester pectin gel

system shows a time lag.

The pectin jellies used in confectionery are produced from high-methoxy, slow-set pectins

with a typical degree of esterification of 60-64%. Since pectin gels are so-called chemo-gels,

i.e. gelation is induced by a decrease in pH, an aqueous sugar solution containing pectin is

boiled to about 106°C in slightly alkaline medium (pH= 7.5-8) containing the sequestrant

(buffer) di/trisodium citrate

Figure 11.2 shows a schematics layout for pectin jelly technology. The technology is sensitive

to the hardness of the water used; therefore, the amount and pH of the buffer are fitted to the

circumstances of manufacture. The duration of gelation is relatively short, 2-3h, with makes

the technology very productive. The water content of the end product is about 21-23%, which,

depending on the condition of storage, may decrease slowly to about 15% because of the

effect of synerisis in about months.

Pectin jellies are favoured because, perhaps, they are mostly similar to the natural fruits, wich

also contain pectin; moreover, their texture is such that they are easily split, and the split jelly

are translucent and glassy. These proprieties of the splitting texture and translucency are the

very quality requirements of confectionery jellies.