Pc. Singh et al., EVALUATION OF IN-LINE SENSORS FOR PREDICTION OF SOLUBLE AND TOTAL SOLIDS MOISTURE IN CONTINUOUS PROCESSING OF FRUIT JUICES/, Food control, 7(3), 1996, pp. 141-148
Three inline sensors: Near-infra red (NIR) (Protonics P-112, Katrina I
nc, Hagerstown, MD); Guided Microwave (Epsilon industrial Inc, Austin,
TX) and Maselli refractometer (Maselli Measurements Inc, Stockton, CA
) were evaluated for continuous measurement of soluble and total solid
s/total moisture in continuous processing of (8-16 Brix) apple, grape,
pear; apple-cherry and apple-banana juices in a pilot scale processin
g unit. Experiments were conducted in the temperature range 21-65 degr
ees C, back pressure of 0-204 kPa, flow rare of 0.756-4.536 kilolit/h,
and acidity of 0.3 to 0.6% malic acid, and pH range of: 3.2-3.9. The
sensors were calibrated by off-line measurement of soluble solids from
an Abbe refractometer and total solids/moisture by standard vacuum ov
en method. The process temperature was found to have great effect on t
he prediction of these sensors. The effects of acidity, back pressure
and flow rate were negligible. High correlation coefficients were obta
ined for calibration curves of the soluble and total solids in differe
nt juices. Maselli refractometer gave excellent results for soluble so
lids under different operating conditions. NIR Katrina analyser and GM
Epsilon spectrometer gave goon results for soluble and total solids.
The sensors were found to give reproducible results after prolonged us
e and were not found to have any deposits or buildups. The present res
earch shows that these sensors can satisfactorily be used for in-line
processing of different juices in industries. Copyright (C) 1996 Elsev
ier Science Ltd.