Collection of acerola (Malpighia punicifolia L.) in passing processes using combined osmotic dehydration and drying

Author(s)

Denise Gomes Alves

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2003-12-12

Examining board members

Fernanda Elizabeth Xidieh Murr; Kil Jin Park; Patricia Moreira Azoubel; Monica Elisabeth Torres Prado; Carlos Alberto Gasparetto

• Advisor: Fernanda Elizabeth Xidieh Murr

Abstract

In the present work it was studied the influence of the osmotic dehydration process using binary (sucrose+water) and ternary (sucrose+salt+water) solutions in the convective drying of acerola fruit (Malpíghía punícífolía L.). Pretreatments were evaluated by influences of immersion time (30 and 90 minutes), temperature (25 and 60°C) and sucrose concentration (30 and 60% w/w) for binary solution and sucrose concentration (20 and 50% w/w) for the ternary solution (10% of salt), on responses of weight loss, water loss, solid gain and solid gain/water loss ratio. For each solution, a condition was stablished to proceed to the convective drying and that condition was determined by the smallest value of the solid gain/water loss ratio. The chosen conditions were: binary solution with 60% of sucrose and ternary solution with 50% of sucrose and 10% of salt, both in the same temperature of 60°C and same immersion time (90 minutes. Influences of temperature (43, 50,60, 70 and 77OC) and air velocities (0,50; 0,65; 1,00; 1,35 and 1,50 m/s) on responses water activity (aw), vitamin C loss (PC) and drying time (ts). Osmotically dehydrated acerola fruit with ternary solution presented smaller values of aw, PC and ts. Frozen acerola fruit presented the largest values of aw, PC and ts, while osmotically dehydrated acerola fruit with binary solution presented intermediate values as compared to other conditions. For sensorial analysis they were chosen samples with smaller values of aw, PC and ts. The frozen acerola fruit was not evaluated in sensorial analysis because presented very high values of aw, close to the values presented by fresh fruit. Osmotically dehydrated acerola fruit with binary solution was more acceptable, with acceptance values in the categories "Iiked lightly" and "liked moderately. (AU)