The Effect Of Enzyme-Hydrolyzed Pumpkin(Cucurbita Moschata Duch.)Pulp Supplementation On Bread And Cake Quality

The aim of this study was to assess whether an enzyme-treated pumpkin pulp(EPP)could be applied as an ingredient for bakery products.Pumpkin pulp(PP)was enzymatically treated by cellulase,pectinase,thermostable α-amylase,or their complex enzymes,then the different types of enzyme-treated pumpkin pulp were analysed for their composition.Treatment condition for the EPP were determined,then PP or EPP was substituted in a certain proportion for water in processed food formulations.The effects of PP and EPP additions on the texture and fermentation characteristics of the bread dough were analysed,as well as on the bakery,textural and microscopic characteristics of the bread.In addition,the effects of PP and EPP additions on the density and microstructure of the cake batter,as well as on the bakery qualities and textural properties of the cake,were also determined.The main results are as follows:(1)Cellulase,thermostable α-amylase,pectinase and complex enzymes treatment have an effect on the composition of PP: The cellulose content of PP after cellulase treatment decreased by34% and the reducing sugar content increased by 83%;the pectin content decreased by 14% and the reducing sugar content increased by 16% after pectinase treatment;the starch content decreased by 43% and the reducing sugar content increased by 236% after thermostable α-amylase treatment;after treatment with both pectinase and cellulase,followed by α-amylase treatment,the cellulose,pectin and starch contents were reduced by 34%,14% and 26%,respectively,and reducing sugars increased by 264%.The results indicated that these enzymes partially degrade cellulose,pectin and starch components and convert them to corresponding reducing sugars.(2)PP and EPP influence the fermentation and textural properties of the dough and on the quality of the bread: 25% and 50%(on fresh basis)PP or EPP addition to wheat flour decreased the volume of the dough after fermentation compared to the control dough,but increased hardness,chewiness,and adhesiveness.PP improved these indicators more than EPP at the same level of addition,suggesting that EPP may have weakened the effect of PP on the textural properties of the dough through enzymatic digestion.The bread with PP or EPP addition was close to the control bread samples in terms of moisture,fat,protein and total sugar content,but increased in ash and crude fiber content.Compared to the control bread,the volume,specific volume,and baking loss rate were reduced,the four texture indices,namely hardness,chewiness,springiness and adhesiveness,and the redness value and yellowness value were increased in the bread with PP or EPP addition.The internal texture structure analysis showed that PP or EPP increased the cell density of the bread,with a corresponding decrease in cell area and porosity.Moreover,PP can influence these indicators more than EPP.In terms of colour,flavour and overall acceptability,bread with the addition of PP and EPP scored higher than the control bread,with the addition of 25%EPP having the most significant effect and the highest overall acceptability.(3)PP and EPP influenced the microstructure and density of cake batter and quality of cake:50% and 100%(on fresh basis)PP or EPP addition resulted in a reduction in the bubble area fraction and number of bubbles in the cake batter,a more compact internal structure,an increase in the specific gravity of the batter and a reduction in the air holding and aeration capacity of the cake batter.Meanwhile,PP or EPP increased the protein,ash,crude fibre and β-carotene content and decreased the fat and total sugar content.Compared to the control cake,PP or EPP resulted in an increase in cake hardness,chewiness,adhesiveness,redness and yellowness,but a decrease in specific volume,volume,shrinkage rate and baking loss rate.The internal texture structure analysis showed that PP or EPP increased the cell density of the cake,with a corresponding decrease in cell area fraction and.roundness value.Sensory evaluation results showed that cakes with 50% EPP addition were the most acceptable,and has little effect on flavour,increased hardness and chewiness,and improved taste,appearance and colour.In summary,although the addition of PP and EPP induced several adverse impacts on the quality of cake and bread,such as reduced volume and increased hardness,it could be regareded as a potential bakery product ingredient in terms of nutritional and sensory value.