Effect Of Processing Parameters On The Rheological And Physico-Chemical Properties Of Varietal Applesauce

Abstract

Applesauce is made from a blend of varieties and processed year round due to the availability of apples from cold storage and controlled atmosphere storage, factors that affect applesauce quality. Applesauce attributes are also affected by processing operations; thus, understanding how these factors influence the final product will help to improve applesauce quality. Our goals were to assess the effect of processing parameters on rheological, physical and chemical properties of applesauce, considering variety and ripening effects, and to optimize processing conditions to improve sauce quality. We investigated the following factors: hot and cold break process; extractor rotational speed; addition of diced apples to extractor sauce output; addition of exogenous pectin methyl esterase (PME) and calcium; and activation of endogenous PME. Samples were analyzed for rheological properties (consistency index, yield stress, USDA consistency values) and physico-chemical properties (particle size distribution, pH, soluble solids, pectin content, pectin degree of methoxylation (DM)). Results were evaluated by ANOVA and Tukey's HSD test (p ! 0.05). Best sauce quality (thicker sauce with low syneresis) was achieved when applesauce had a mean particle size ! 700 [MICRO SIGN]m, particle size distribution span " 1.75, total soluble pectin " 0.25%, and pectin DM ! 60%. Ripening or processing conditions could modify these parameters to meet targeted applesauce rheology. Processing effects differed with variety and ripening stage. Overall, higher rotational extractor speed and addition of "50% diced apples to extractor sauce output prior to final pulping, resulted in increased sauce viscosity and decreased syneresis, due to an increase in total soluble pectin, a lower mean particle diameter and a wider particle size distribution. Exogenous PME addition caused a decrease in pectin DM, leading to higher sauce viscosity and less syneresis. When PME and Ca2+ were added, viscosity was highest but resulted in higher syneresis. Activation of endogenous PME at 5560°C for 10 min lowered the pectin DM from 83% to 60-70% but no change on applesauce rheology was observed. By understanding how sauce physico-chemical and rheological properties are affected by variety, ripening and processing parameters, it is possible to optimize all relevant conditions to achieve better consistency and quality.