Quality Characteristics of Biscuit Produced With Wheat-sweet Potato Composite Flour
Chapter One
Objectives of study
- To ย ย know the means of making biscuits from sweet potato flour
- ย ย To ย ย learn the characteristics of biscuits made from potato flour
ย CHAPTER TWO
ย Definition of Compositeย Flours
Compositeย floursย areย quiteย differentย fromย the ready-mixed flours familiar to millers and bakers. Whereas ready-mixed flours contain allย theย non-perishableย constituentsย ofย theย recipe forย aย certainย bakedย product,ย compositeย flours areย onlyย aย mixtureย ofย differentย vegetableย flours richย inย starchย orย protein,ย withย orย withoutย wheat flour, for certain groups of bakery products. Thisย givesย riseย toย theย followingย definition:
“Composite flours are a mixture of flours fromย tubersย richย inย starchย (e.g.ย cassava,ย yam, sweetย potato)ย and/orย protein-richย floursย (e.g. soy, peanut) and/or cereals (e.g. maize, rice, millet, buckwheat), with or without wheat flour” 24ย .
ย Composition of Compositeย Flours
Theย goalย ofย earlierย researchย withย composite floursย wasย toย saveย theย largestย possibleย percentage of wheat flour in the production ofย certain bakedย products.ย Theย extentย toย whichย wheat flourย couldย beย replacedย byย otherย vegetable floursย naturallyย dependedย onย theย natureย ofย the products to beย baked.
Breadย andย Smallย Bakedย Goods
Trials with composite flours with and without wheat flour were carried out for this purpose. The composite flours containing wheat flour usually consistedย ย ofย ย 70%ย ย wheatย ย flour,ย ย 25% maize/cassava starch and 5% soy flour. But there were tests in which the composite flour contained no wheat flour at all โ for example 70% cassava flour or starch and 30% peanut and/or soy flour.
ย pastry goods
In this field the focus of the tests was on producing hard and soft biscuits, with or without the use of wheat flour. As a rule, the composite flour containing wheat consisted of 70 – 80% wheat flour and 20 – 30% soy flour. In cases where no wheat was included, a mixture of 100% sorghum/millet flour or 50% cassava starch, 20% milk powder and 30% soy flour was used.
pasta
In this field the focus of the tests was on producing hard and soft biscuits, with or without the use of wheat flour. As a rule, the composite flour containing wheat consisted of 70 – 80% wheat flour and 20 – 30% soy flour. In cases where no wheat was included, a mixture of 100% sorghum/millet flour or 50% cassava starch, 20% milk powder and 30% soy flour was used.
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In this field the focus of the tests was on producing hard and soft biscuits, with or without the use of wheat flour. As a rule, the composite flour containing wheat consisted of 70 – 80% wheat flour and 20 – 30% soy flour. In cases where no wheat was included, a mixture of 100% sorghum/millet flour or 50% cassava starch, 20% milk powder and 30% soy flour was used.
Technical problems at the bakery
In this field the focus of the tests was on producing hard and soft biscuits, with or without the use of wheat flour. As a rule, the composite flour containing wheat consisted of 70 – 80% wheat flour and 20 – 30% soy flour. In cases where no wheat was included, a mixture of 100% sorghum/millet flour or 50% cassava starch, 20% milk powder and 30% soy flour was used. The limit for the addition of cassava/ maize rice to wheat flour for bread and small baked products is at least 50 – 80% wheat flour. The percentage depends on the baking quality of the imported wheat flour concerned. In the case of ย biscuits it is possible to replace wheat flour completely.
ย ย CHAPTER THREE
ย MATERIALS ANDย METHODS
Preparation of Sweet Potatoย Flour
The sweet potatoes tubers were purchased from Apata market in Ibadan and the potato skin were peeled off from the tuber, the edible portion of the sweet potatoes were washed in clean tap water, before they were sliced into pieces and sun dried. After two weeks of sun drying, the dried potatoes chips were milled into sweet potato flour and the sweet potato flour were sieved to obtain fine flour and stored in plastic containers with lids in a refrigerator from where samples were drawn for Biscuits preparation. Wheat flour was purchased from local shop where they are sold and were stored in plastic containers with lids in a refrigerator.
Preparation ofย Biscuits
CHAPTER FOUR
PHYSICO-CHEMICAL ANALYSIS OFย SAMPLES
Bulk density of the flour Samples
The bulk density of the floor samples was determined by Wang and Kinsella method (1976). Sweet potato flour, maize flour, and their blends (10g) each was weighed into 50ml graduated measuring cylinder. The sample was packed by gently tapping the cylinder on the bench top 10times from a height of about 5cm. the volume of each sample was recorded.
ย CHAPTER FIVE
Discussion of finding, conclusion and recommendations
Findings
There ย was increase in moisture as more potato flour is added to wheat flour; this result is in agreement with the work of (Khaliduzzaman etย al.,ย 2010)ย whenย he supplementedย wheatย flourย withย 20%ย potatoย flour in ย making ย biscuits. ย Carbohydrate ย value ย range ย between ย 56.52g/100g ย and ย 64.75g/100g; ย the highestย value wasย recordedย inย 100:0ย ratiosย ofย wheat-sweetย potatoย biscuit.
Despite the fact that mineral content of raw wheat are higher than mineral content of raw sweet potato, it was observed from the results that the mineral value of calcium, magnesium, potassium, sodium and phosphorus are higher in biscuits made from ratio 90:10, 70:30, 60:40 and 50:50 wheat- sweet potato composite flour than biscuits made from ratio 100:0 of wheat-sweet potato composite flour. These results suggest that biscuit of good mineral content can be produced when wheat flour is substituted with sweet potatoย flour.
The bulkย densityย isย aย reflectionย ofย the loadย theย samplesย canย carryย ifย allowedย toย restย directlyย on oneย another.ย Theย resultsย showedย thatย flourย mixtureย ofย ratioย 100:0ย wheat-sweetย potatoย composite flour ย has ย higher ย valueย (0.9091g/cm3)ย of ย Bulk ย Density, ย whileย theย lowest ย valueย (0.7407g/cm3) ย of bulk ย density ย was ย recorded ย in ย flour ย mixture ย of ย ratio ย 60:40 ย wheat-potato ย composite ย flour. ย The particleย sizeย andย theย densityย ofย flourย orย flourย mixturesย generallyย affectย theย bulkย densityย andย itย is veryย importantย inย determiningย theย packagingย requirement,ย rawย materialย handlingย andย application inย wetย processingย inย the foodย industryย (Adebowaleย etย al.,ย 2008;ย Ajanakuย etย al.,ย 2012).ย Flourย ofย ratio 100:0 wheat-potatoย compositeย flour hasย theย highest (2.41g/g)ย Waterย Absorption Capacity,ย and the mixedย ofย ratioย 60:40ย hasย the lowestย (1.88g/g)ย Waterย Absorptionย Capacity.ย Flourย ofย ratioย 100:0 wheatโsweet potato, has higher affinity for water, which is informed by its lower moisture contentย 9.34%.ย Thisย couldย beย indicativeย ofย theย factย thatย wheatย flourย confersย highย waterย binding capacity than potatoย flour, which causesย the reconstitution ability and textural properties ย of doughย obtainableย fromย wheatย compositeย flourย toย beย betterย thanย thatย ofย wheat-sweetย potatoย flour composite.ย However,ย wheat-sweetย potatoย flourย compositesย displayย acceptableย bindingย properties duringย preparation,ย whichย suggestย thatย theย combinationย ofย wheat-sweetย potatoย compositeย canย be use in making biscuit. The lose structure of starch polymers causes it to possess high water absorption capacity while products with low value indicates the compactness of such product structure.
Oneย ofย theย mostย importantย propertiesย thatย influenceย qualityย andย aestheticย considerationsย in theย foodย industryย isย theย pastingย property,ย andย theyย affectย textureย andย digestibilityย asย wellย asย the endย useย ofย starch-basedย foodย commodities. ย Peakย viscosityย whichย rangedย betweenย 366.83RVUย to
407.50ย RVUย isย anย indexย ofย theย abilityย ofย starch-basedย fruitsย toย swellย freelyย beforeย theirย physical breakย downย (Sanniย etย al.,ย 2006).ย Theย Troughย valueย rangesย fromย 236.33RVUย toย 291.08RVU,ย with biscuits ย made ย from ย ratio ย 90:10 ย wheat-sweet ย potato ย flour ย having ย the ย highest ย value ย and ย biscuits made ย from ย ratio ย of ย 50:50 ย wheat-sweet ย potato ย flour ย having ย the ย lowest ย value. ย Trough ย is ย the minimum ย viscosity ย value ย in ย the ย constant ย temperature ย phase ย of ย the ย RVA ย pasting ย profile ย and ย it measuresย the abilityย ofย the paste toย withstandย breakย downย duringย coolingย (Adebowaleย etย al.,ย 2012). The ย highest ย Break ย Down ย Viscosity ย (89.08ย ย RVU) ย was ย recorded ย on ย biscuit ย produced ย from ย ratio 50:50ย wheat-sweetย potatoย compositeย flour,ย whileย biscuitsย producedย fromย ratioย 100:0ย wheat-sweet potato ย composite ย flour ย has ย the ย lowest ย breakdown ย viscosity ย (54.67 ย RVU). ย The ย Final ย Viscosity ranged ย between ย 286.92RVU ย and ย 329.25 ย RVU ย with ย biscuit ย of ย ratio ย 90:10 ย wheat-sweet ย potato composite ย flour ย having ย the ย highest ย value ย and ย biscuits ย of ย ratio ย 50:50 ย wheat-sweet ย potato ย flour havingย theย lowestย valueย (329.25RVU).ย Finalย viscosityย isย commonlyย usedย toย defineย theย qualityย of particularย starch-basedย flour,ย sinceย itย indicatesย theย abilityย ofย theย flourย toย formย aย viscousย pasteย after cooking ย and ย cooling ย (Adebowaleย et ย al., ย 2012). ย Theย setback ย valueย ranged ย between ย 70.33RVU ย to 107.58RVU.
There was an increase in setback value as the percentage of sweet potato flour increases in the biscuit. The higher the setback viscosity the lower the retro-gradation of the flour paste during cooling and the lower the staling rate of the product made from the flourย (Adeyemi andย Idowu, 1990). The Peak time is a measure of the cooking time, and it ranged between 7.50minย and
8.93ย min,ย withย biscuitsย producedย fromย ratioย 90:10ย wheat-sweetย potatoย compositeย flourย havingย the highestย value ย and ย biscuits ย made ย from ย ratio ย 100:0 ย wheat-sweet ย potato ย flour ย having ย the ย lowest valueย ofย 7.50min.ย Pastingย temperatureย rangedย fromย 68.35OCย toย 91.40ยฐC,ย andย theย highestย pasting temperatureย wasย recordedย inย biscuitsย madeย fromย ratioย 90:10ย wheat-sweetย potatoย compositeย flour. Adebowaleย etย al.,ย 2008ย statedย thatย aย higherย pastingย temperatureย isย anย indicationย ofย higherย water binding ย capacity, ย higher ย gelatinization ย tendency ย and ย lower ย swelling ย property ย of ย starch-based flourย asย aย result ofย highย degree ofย associationย betweenย starchย granules.
The results of Sensory evaluations reveal that biscuits produced from ratio 100:0 wheat- sweet potato composite are not significantly different (pโฅ0.05) in taste from biscuits made from ratio 90:10 and 70:30 wheat-sweet potato composite flour, but there was significant difference (pโค0.05) in taste between biscuits made from ratio 100:0 and biscuits produced from ratio 60:40 and 50:50 wheat-sweet potato composite flour. The results of the evaluation also reveal that there were no significant (pโฅ0.05) difference in colour and overall acceptability between biscuits produced from ratio 100:0 wheat-potato composite flour and biscuit made from ratio 90:10, 70:30, 60:40 and 50:50 wheat-potato composite. During evaluation, most of the panelist shown that biscuits made from ratio 100:0 and 90:10 are more acceptable, when they where ask to comment freely on the products, however, no significant differences was seen when the results were analyzed statistically.
Chinma et al. (2012) got a similar result in his sensory evaluation when he used unripe plantain to supplement wheat flour in the production of cookies; these results suggested that wheat flour could be supplement with other staple food samples in the production of biscuits and other baked food.
CONCLUSION
This research work was carried out in order to test for the nutritional, functional and sensory qualities of wheat-potato composite biscuits. The use of potato in supplementing wheat flour in biscuit production has significant benefits in countries where inadequate wheat is grown. Therefore, incorporation of sweet potato flour in biscuit production will reduce the quantity of wheat that will be imported, thereby reducing the cost of production of biscuits. Supplementing wheat with sweet potato flour in biscuits production will reduce over reliance on the use of wheat flour in biscuits production and other baked products, and it will enhance the utilization of sweet potato in the Nigeria. If wheat importation is reduced, and attention is given to potato farming, it will help strengthen the economy of the nation and provide income to farmers. A substantial amount of potato is spoiled and wasted due to inadequate cold storage facilities and insufficient post-harvest handling facilities in many developing countries. The experiments produced biscuits of acceptable Nutritional, Functional and Sensory qualities from all ratios of wheat-potato flour that was used; therefore, these research findings have unveil new windows for further utilization of sweetย potato.
REFERENCES
- Adebowale, A.A., M.T. Adegoke, S.A. Sanni, M.O. Adegunwa and G.O. Fetuga, 2012. Functional properties and biscuit making potentials of sorghum-wheat flour composite. American Journal of Food Technology, 7: 372-379.
- Adebowale,ย A.A.,ย L.O.ย Sanniย andย M.O.ย Onitilo,ย 2008.ย Chemicalย compositionย andย pastingย propertiesย ofย tapioca gritsย fromย differentย cassavaย varietiesย andย roastingย methods.ย Afr.ย J.ย Foodย Sci.,ย 2:ย 77-82.
- Adeyemi, ย I.A. ย andย M.A. ย Idowu, ย 1990. ย Theย evaluationย of ย pregelatinized ย maizeย flourย in ย theย developmentย of Maissa.ย Aย bakedย product.ย Nig.ย Foodย J.,ย 8:ย 63-73.
- Ajanaku, K.O., C.O. Ajanaku, A. Edobor-Osoh and O.C. Nwinyi, 2012. Nutritive value of sorghum ogi fortified with groundnut seed (Arachis Hypogaea L.). American Journal of Food Technology, 7: 372-379.
- Akpapunam, M.A. and J.W. Darbe, 1999. Chemical composition and functional properties of blend of Maize Barbara groundnuts flours for cookie production. Plants Food for Human Nutri., 46: 147 -AOAC,