44C-4 |
Thermal activation of pectinesterase in jalapeño pepper (Capsicum annum) |
M. L. REYES-VEGA, E. G. Alba-Villarreal, C. N. Aguilar-Gonzalez, J. C. Contreras-Esquivel, and H. De la Garza. Food Research Dept., Univ. Autonoma de Coahuila, Blvd. V. Carranza e Ing. Jose Cardenas, Saltillo, Coahuila, 25280, Mexico Jalapeño pepper (Capsicum annum), a vegetable used in many Mexican dishes, is usually blanched at 90°C, 1 – 5 minutes to inactivate some enzymes that degrade its quality and subsequently canned in vinegar. This process affects its texture, weakening its structure. These changes are frequently undesirable. Food technologists have experienced great difficulty in processing foods that closely simulate native foods. The turgor that provides much of the crispness of fresh fruits and vegetables arises from the physiological activity of the living tissue. Pectinesterase (PE) is an enzyme of vegetable tissues; it demethyloxylates pectins. This reaction allows the interaction of the carboxilic groups with calcium ions in the tissue, producing calcium pectates, which provide a firmer structure. The main objective of this work is to improve textural attributes of Jalapeño pepper by means of in situ thermal activation of PE. Temperatures considered were 60 and 65°C during 20, 40 and 60 minutes. It was determined enzyme activity (Kertesz method), texture (puncture with flat-end punch) and color (parameters L, a, b). The results indicated that maximum PE activity is achieved when pepper was immersed in distilled water at 60°C during 40 and 60 minutes (27.9 and 29.5 U/mL, respectively). The higher resistance force to puncture test was obtained in the sample treated at 60°C during 40 minutes (1.83 + 0.3 kg-f, aproximately 6% more than untreated pepper). This was also the treatment which showed the least variation in color (L, +2.64; a, -0.61; b, +3.07) with respect to the untreated sample (L, +0.52, a, -0.16, b, +0.61). From these results it can be observed that the thermal activation of Jalapeño chili at 60°C during 40 minutes enhances the PE activity and the firmness of the vegetal tissue and preserves its original color better than the other treatments.
Session 44C, Fruit & Vegetable Products: Chemistry
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