NO - Besoin d'assistance

Processing and Bioavailability (WG2) page 30
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10 Peeling (whole and non-whole
peeled tomatoes)
Survey of references:
L
D
L Reduce the loss of under-peel pulp
D Use steam temperatures as low as possible
Sharma and Le Maguer (1996b) observed that in the fresh tomato lycopene is located
above all in the insoluble fraction and that the concentration in the outermost layer (pulp thick
fraction, rather vaguely defined) is 5 times greater than in the pulp, although the ratio goes
down to 1:2 if referring to dry weight.
Nguyen and Schwartz (1998) reported that the lye peeling of tomatoes (treatment in 18%
NaOH at 82 °C for 15 sec) did not cause significant lycopene loss or isomerisation (results
were expressed on a d.w. basis). The lycopene content and isomeric distribution found in
tomato products produced at the University centre showed that lye peeling of tomato,
maceration prior to juicing, pasteurisation of the juice (82°C for 15 sec), canning and heating
at 104°C for 50 min of whole peeled tomatoes did not significantly affect either the formation
of lycopene isomers or their relative abundance.
Comments and topics.
It is rather difficult to isolate the various tissues (esocarp and mesocarp) completely,
hence the analytical data remain uncertain. The peeling technique now almost universally
adopted (only in the USA are there a few NaOH peeling lines still in operation) involves
scalding the tomatoes with high pressure steam (2-3 bar) for a few tens of seconds to heat the
water content of the cells under the peel, followed by a sudden reduction in pressure, which
causes the heated water to evaporate and the cells to break, so that the peel comes away from
the pulp. The pressure can be lowered by the addition of cold water, or else by connection to a
vacuum system; in the first case, the surface of the tomato is washed away, with a consequent
loss of substance and thus also of lycopene.
Is this step an RCPL ?
Q1 Q2 Q3 Q4 result
Yes Yes Yes