Firmness and cell wall characteristics of pasteurized jalapeno pepper rings affected by acetic acid, calcium chloride and preheating

Abstract

Consumption of jalapeno peppers has increased due to the great popularity of Mexican style foods. Fresh jalapenos are noted for their unique flavor, heat and crisp texture. Unfortunately, fresh peppers lose their crisp texture during commercial pasteurization and storage, especially when high acid brines are used. Development of treatments to retard softening may result in a higher quality product. This study was undertaken to investigate the effects of calcium chloride (CaCI2), acetic acid, and preheating treatments on firmness and cell wall characteristics of pasteurized jalapeno rings. Brine treatments included three levels of acetic acid (0. 9 %, 1. 1 % and 4 %), with and without 0.2% CaC'2. For preheating peppers were incubated at 40'C for 60 minutes in 8% NaCl and 0.2% CaC'2and then processed in brine containing 0. 9 % acetic acid and 0. 2 % calcium chloride. The control received no preheating treatment. Peppers were pasteurized to an internal temperature of 74'C, and held for 15 min. Texture, water soluble pectins (WSP), chelator soluble pectins (CSP), dilute alkali soluble pectins (OHSP), non-extractable pectins (NXP), and pectin degree of esterification (DE) were measured after 0.5, 1, 2, 3, 4, and 5 months storage at 230C. Pepper rings packed in brine containing CaC'2 were firmer, had greater levels of CSP and pectin DE, and lower levels of WSP than peppers packed in brine containing no CaC'2-Pepper rings packed in low acid brines (0. 9 % and 1. 1 % acetic acid) were finner and had lower levels of WSP than peppers packed in high acid brine. High acid brine treatment (4% acetic acid) resulted in softening and pectin solubilization, but CaC'2ameliorated softening under high acid conditions. Improved firmness in CaC'2 treated samples was probably due to greater association between Ca" ions and pectic substances, which resisted acid hydrolysis. Pepper rings which were preheated had lower levels of WSP, OHSP, and higher texture values and levels of NXP than non-preheated peppers. Preheated peppers were firmer than the control. Firmness enhancement during preheating might be due to activation of pectin methylesterase and creation of more binding sites for calcium.