The Purification and Estimation of Pectin

Spencer, G C

doi:10.1021/j150308a016

Cited by 1 publication

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“…Various authors have stated, however, that it is rather difficult to remove the last traces of ash by precipitation or dialysis (10,18,19), especially iron and aluminum.…”

Section: Discussionmentioning

confidence: 99%

“…Experiments with cooling jellies to a constant temperature employed pectins with had been purified by two-fold precipitation in 70% acetone at pH 1.5 followed by washing in pure acetone. Various authors have stated, however, that it is rather difficult to remove the last traces of ash by precipitation or dialysis (10,18,19), especially iron and aluminum.…”

Section: Discussionmentioning

confidence: 99%

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Setting Time and Setting Temperature of Pectin Jellies

Doesburg¹,

Grevers²

1960

Journal of Food Science

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Setting time is defined by Kertesz (15) as "the interval of time which elapses between the instant at which all constituents of a jelly batch (sugar, pectin and acid) are placed in the final container after cooking and that instant at which jellification of the whole into a coherent mass may be observed." ' However, it should be remembered that in some cases setting may occur during the cooking, as has been shown bv Cole, Cox and Joseph (4). For this reason it seems better to define setting time as the time between the moment that all ingredients necessary for forming the jelly are present in heated solution in the correct proportion and the moment that jellification into a coherent mass occurs.Hinton (13) has stressed that the setting temjerature of a jelly is shown to be a determinate physical property, whereas the setting time is a secondary property dependent on temperature conditions. According to Hinton the time of setting for a certain jelly batch is governed by the velocity at which the setting temperature of the mixture is reached. The more quickly a jelly batch is cooled, the lower the setting temperature may become due to undercooling. After determining the setting temperature of a batch at different cooling rates, it is possible to calculate by extrapolation the setting temperature when the cooling rate is zero. Hinton states that the setting temperature, calculated in this way and corresponding with infinitely slow cooling, coincides within experimental limits of accuracy with the i-e-melting temperature during heating.Kertesz (1.5), writing in 19.51, noted a lack of published data on the setting time of pectin jellies. Methods for its determination had been described by Baier (14) in 1949 and earlier, in 1939, by Olsen, Stuewer, Fehlberg and Beach (18) but data had not yet accumulated and this is relatively true today.Olsen, Stuewer, Fehlberg, and Beach (18) have also described the influence of the degree of esterification of pectins, indicating that setting time is increased by lowering the degree of esterification from about 75% to about 60% and that further saponification tends to decrease the setting time. These studies were made with jellies at pH 3.1.It is well known that the setting time of a jelly batch is influenced by the pH, a lower pH effecting a more rapid jellification (7,14,15). Increasing the sugar content of the batch also has an influence, causing a decrease in setting time (4).According to Baker and Goodwin (1) high jelly grade pectins tend to show longer setting times. Th ey found a relation also between degree of esterification and setting time, but stated that high-ester pectins are not always rapid-set pectins. Lampitt and Money (16) observed an increase in 634

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“…Various authors have stated, however, that it is rather difficult to remove the last traces of ash by precipitation or dialysis (10,18,19), especially iron and aluminum.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%