Developing Baking-Stable Red Raspberries with Improved Mechanical Properties and Reduced Syneresis

Abstract

This work identified new treatments to develop red raspberries for baking applications for better consumer appeal. Fresh or frozen fruits are often incorporated in baked products such as muffins and pies. These baked products are very popular due to their fresh, fruity flavor. Raspberries are used as an ingredient in many foods due to their delicious flavor. However, the incorporation of red frozen raspberries turns the baked product red due to syneresis during baking. In this study, we developed baking-stable red raspberries to minimize syneresis during baking. We applied three treatments to the red raspberries: vacuum impregnation with low methoxyl pectin and calcium chloride at 20 °C and a vacuum level of 50.8 kPa, for 7 min; partial dehydration using hot air at a dry bulb temperature of 65 °C until the final water content of 0.65 g H2O/g fruit was reached; and edible coatings at different concentrations. Treated berries were stored in a freezer at −\u200935 °C for 2 months. We determined the mechanical properties, drip loss, and visual integrity of the frozen-thawed red raspberries before baking to select appropriate coatings. Raspberry muffins were then baked to 204 °C for 20 min. We determined the syneresis from the baked fruit using an image analyzer. Findings indicate that sodium alginate coating on red raspberries at 0.4% (w/v) resulted in minimal syneresis in baked muffins at 13.9%, while commercially frozen raspberries showed syneresis at 62.9%. The maximum force (FM) and gradient (GC) values as firmness indicators were improved from control berries (7.45 N and 2.06 N/mm, respectively) to treated berries (21.16 N and 7.06 N/mm, respectively).