The effect of part-baking, freezing, frozen storage, thawing and rebaking on the quality of bread has been investigated. Quality evaluation of the stored bread was done using sensory analysis, instrumental texture profile analysis (TPA) and cutting tests of the crumb and crust. It was found that frozen bread with 71% fraction of baking time showed high stability of sensory features and rheological parameters during the entire storage period (11 weeks) and, after thawing and rebaking, had superior quality in comparison with its frozen and thawed full-baked (100%) counterpart. Second-order regression showed that the optimal time for the initial prebaking lies within the wide range from 74 to 86% of the time needed for the full-baking of unfrozen bread. It is therefore a good method for preventing the staling process and obtaining a product of a quality close to that of fresh, not frozen bread. It has also been shown that a fraction of baking time equal to 43% was too small to ensure desirable sensory and textural features of bread after its frozen storage and rebaking.

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Minced heads of broiler chickens were hydrolysed under various conditions using porcine pepsin. It was found that hydrolysis goes at an optimum rate at 55°C and pH 1.5 following the addition of 750 g water and 3 g pepsin per kg raw material. After 5 h of proteolysis, 1 kg of the raw material yielded 144 g of dry unneutralised hydrolysate containing 15.7 g total nitrogen, equivalent to a 67.8% nitrogen recovery. Neutralisation prior to drying marginally decreased nitrogen recovery and reduced the nitrogen solubility index by > 30%. The final dried products were pale cream coloured, had no bitter taste, were of high microbiological quality and had a high mineral content. Both dried hydrolysates had poor emulsifying properties.

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