Use of vanillin and citral combined with a slight thermal treatment to obtain a minimally processed orange juice

CHAR, C.D.; GUERRERO, S.N.; ALZAMORA, STELLA MARIS

Orlando, USA

Congreso; 2006 IFT Annual Meeting; 2006

IFT

Different techniques are being explored for orange juice preservation to reduce the severity of conventional pasteurization by adding other hurdles, such as natural antimicrobials and refrigeration. The purpose of this study was to evaluate the effect of vanillin and citral addition combined with slight thermal treatments on native flora and sensory perception of orange juice. Fresh squeezed and centrifuged orange juice added with 900 ppm of vanillin and 25 ppm of citral was pumped (1.1 L/min) through a double wall serpentine-like lab scale device to be thermally treated at 52°C or 57ºC for 4'42"or 1'18", respectively and stored at 5ºC during 15 days. Holding times were determined in a previous research for a 5 log cycle reduction of L. innocua (surrogant of L. monocytogenes). Native flora (aerobic and anaerobic mesophilic or thermophilic aerobic count, mesophilic and thermophilic acid tolerant bacteria, mold, and yeasts) was determined along the storage following standard enumeration procedures. Sensory differences between treatments and global acceptance were evaluated by a trio test and a 9-point hedonic scale, respectively, using a panel of 60 consumers. Total mesophilic aerobic and acid tolerant bacteria were greatly reduced by the treatments, being this effect stronger at 57ºC. Mold and yeast population was dramatically reduced at 57ºC but was poorly affected at 52ºC. Microbial evolution depended on the initial native flora population. During storage, no significant count changes were observed. The combined treatment at 52ºC was not perceived by consumers significantly different from the one at 57ºC. The averaged global score resulted in the center of the scale: neither like nor dislike it. The proposed combination of vanillin and citral addition with mild heat treatment at both temperatures effectively reduced native flora, increasing orange juice microbiological quality without modifying, to a large extent, its sensory perception.