Studies On The Shelf-life Of French Frozen Dough And Roll

The paper was aimed at extending the shelf-life of French roll by controlling many import- ant factors. Our investigation involved optimizing dough formulation, storage temperature and proofing time, evaluating the effect of Ice Structuring Protein (ISP) on fermentation and thermodynamic characteristics of frozen dough and baking systems, assessing the effect of Modified Atmosphere Packaging (MAP) on the shelf-life of French roll. Furthermore, it was demostrated that water mobility plays an important role in frozen dough and frozen dough French roll shelf-life at molecular level using a low-field pulsed Nuclear Magnetic Resonance (NMR).Proofing time of French roll were 90min, 90min, 110min for fresh dough, part-baking dough and frozen dough which has preserved in freezer for 14 days respectively. The optimum formulation of French roll which was obtained by the orthogonality analysis methodology of three levels and three factors was: flour 100.0, water 60.0, shortening 8.0, yeast 1.5, salt 1.0, glycerol 12.0, sucrose ester 1.0, gum 0.5. French roll stored at -18℃showed better quality than any other sample stored at 38℃, 25℃or -4℃.ISP is a protein that has the ability to modify the growth of ice resulting in the stabilization of ice crystals over a defined temperature range and in the inhibition of the recrystallization of ice. The effects of ISP on fermentation and thermodynamic characteristics from the frozen dough, part-baking, and fresh baking systems were described. The specific volume, moisture content, hardness and gelatinization enthalpy of baking systems were determined after frozen storage at -18℃. ISP improved the specific volume of frozen dough French roll. No significant effect of ISP on specific volume was found in other types of French roll. The moisture content with ISP of the bread after different periods of frozen storage was kept constant, while the control samples increased with the time of frozen storage. The hardness of French roll with ISP was softer than control samples which were attributed to the damage of French roll structures produced by the ice crystallization. In all types of baking systems with ISP, the gelatinization enthalpy of baking system is larger than control.In order to understand the physico-chemical properties of frozen dough and the staling process of French roll during storage, in particular the role of water in this process, it is necessary to investigate changes in the states of water over a wider spectrum. The three-component model was found to well represent the states of water in the frozen dough and French roll crumb samples using NMR. The results showed that the amount of T23 state water of frozen dough increased with increasing time, indicating the capability of holding water of frozen dough system decreased as storage time increased, glycerol has a greater ability to associate with water in dough system, ISP also can reduce water mobility of frozen dough. During French roll staling, changes in T2s and the corresponding intensities of protons were complicated, suggesting a dynamic structural transform of macromolecules and microscopic migration of moisture in the staling French roll. T1 was closely related to short term retrogradation. The added glycerol showed retarding the French roll staling.The experiment of MAP demonstrated that no significant effect of MAP was found on French roll stored for 28 days at 25℃compared to control French roll, when changes in French roll hardness measured by texture analyzer and moisture content were used as parameters for the staling rates. In addition, no significant differences were obtained in sensory attributes between French roll stored in 100% CO2, in the mixture gas of CO2 and N2 and air respectively. However, the present study demonstrated that MAP could extend the microbial shelf-life of French roll. Furthermore, the mold free shelf life of French roll increased as the concentration of CO2 in the atmosphere increased. When optimum formulation is available, the shelf-life of French roll can be extended for 1 month at room temperature, using appropriate mixtures of CO2 and N2 (100% CO2 for French roll).