Effect Of Processing Method On The Physio Chemical Properties Of Sweet Potato And Sorghum
The impact of processing methods on the physicochemical characteristics of sweet potato and sorghum is significant, influencing various attributes such as nutritional composition, texture, flavor, and shelf-life. Different processing techniques, including boiling, steaming, roasting, and fermentation, alter the chemical composition and sensory properties of these crops. For instance, boiling sweet potatoes can lead to some loss of water-soluble vitamins, while steaming may preserve more nutrients due to reduced water contact. Similarly, sorghum processing methods like malting or fermentation affect its starch content, leading to changes in digestibility and flavor profile. Furthermore, roasting sweet potatoes and sorghum grains can enhance their aroma and taste through Maillard reactions, while fermentation can improve digestibility and enhance nutritional value through the production of bioactive compounds. Understanding how various processing methods influence the physicochemical properties of sweet potato and sorghum is essential for optimizing their utilization in food products and enhancing their nutritional benefits.
This study evaluated “the effects of processing methods on the physico-
chemical properties of sweet potato and sorghum flour”. Sweet potato
(Ipomoea batatas) is an important food crop in the tropical and sub-tropical
countries and belongs to the family convolvulaceae. Sweet potatoes are rich
in dietary fiber, minerals, vitamins, and anti oxidants such as phenolic acids,
anthocyannins, tocopherol and β-carotene. The proximate composition of
sweet potato was determined and these include moisture, lipids, ash, protein,
carbohydrates and fiber. In carrying out the analysis practically, methods
used vary according to the food material. The anti oxidants were also
determined alongside with phenol oxidase, pasting properties, minerals and
sugar contents. Sorghum is a tropical plant belonging to the family of
poaceae. More than 35% of sorghum is grown for human consumption. The
analyses carried out in sweet potatoes are same with sorghum with the
exclusion of phenol oxidase.
TITLE PAGE
CERTIFICATION
DEDICATION
ACKNOWLEDGEMENT
ABSTRACT
TABLE OF CONTENTS
CHAPTER ONE:
INTRODUCTION
CHAPTER TWO:
LITERATURE REVIEW
2.1. ORIGIN AND DISTRIBUTION OF SWEET POTATO
2.1.1. DESCRIPTION OF SWEET POTATO PLANT
2.1.2. USES OF SWEET POTATO
2.1.3. NUTRITIONAL VALUE OF SWEET POTATO
2.1.4. ANTI- NUTRITIONAL FACTORS
2.1.5. NUTRIENT COMPOSITION OF SWEET POTATO
2.1.5.1. POLYPHENOLS COMPOSITION
2.1.5.2. ANTI-OXIDATIVE, ANTI-MUTAGENICITY AND ANTI-
CARCINOGENICITY
2.1.6. ANTI-DIABETES
2.1.7. ANTI-NUTRIENTS IN SWEET POTATO
2.1.8. ENZYME COMPOSITION OF SWEET POTATO
2.2. ORIGIN AND DISTRIBUTION OF SORGHUM PLANT
2.2.1. DISTRIBUTION OF SORGHUM PLANT
2.2.2. USES OF SORGHUM
2.2.3. ENZYME COMPOSITION OF SORGHUM
2.2.4. NUTRITIONAL COMPOSITION OF SORGHUM
2.2.5. ANTI-NUTRIENTS IN SORGHUM
CHAPTER THREE:
MATERIALS AND METHODS
3.1. MATERIALS
3.2. METHODOLOGY
3.2.1. PROCESSING OF SWEET POTATO TUBER
3.2.2. PROCESSING OF SORGHUM GRAIN
3.3. SWEET POTATO AND SORGHUM ANALYSIS
3.3.1. PROXIMATE ANALYSIS
3.3.1.0. DETERMINATION OF FAT CONTENT
3.3.1.1. DETERMINATION OF ASH CONTENT
3.3.1.2. DETERMINATION OF CRUDE FIBRE
3.3.1.3. DETERMINATION OF MOISTURE CONTENT
3.3.1.4. DETERMINATION OF PROTEIN
3.3.1.5. DETERMINATION OF CARBOHYDRATES
3.4. ANTI-NUTRIENTS AND PHYTOCHEMICALS
3.4.1. DETERMINATION OF TANNINS
3.4.2. DETERMINATION OF HYDROCYANIC ACID
3.4.3. DETERMINATION OF ANTHOCYANNINS
3.4.4. DETERMINATION OF PHYTATE/PHYTIC ACID
3.5. DETERMINATION OF MINERAL CONTENT
3.5.1. MAGNESIUM
3.5.2. IRON
3.5.3. ZINC
3.5.4. PHOSPHOROUS
3.5.5. POTASSIUM
3.6. DETERMINATION OF PASTING PROPERTIES
3.7. DETERMINATION OF PHENOL OXIDASE
3.8. DETERMINATION OF REDUCING SUGARS; FRUCTOSE,
GLUCOSE AND SUCROSE
CHAPTER FOUR: RESULTS AND DISCUSSION
4.1. TABLE 1: PROXIMATE COMPOSITION OF THE SAMPLES
AND DISCUSSION
4.2. TABLE 2: MINERAL COMPOSITION OF SAMPLES AND
DISCUSSION
4.3. TABLE 3: PHYTOCHEMICAL COMPOSITION OF THE
SAMPLES AND DISCUSSION
4.4. TABLE 4: PHYSICO-CHEMICAL PROPERTIES OF
SAMPLES AND DISCUSSION
4.4. TABLE 5: SUGAR COMPOSITION OF THE SAMPLES
AND DISCUSSION
CHAPTER FIVE:
CONCLUSION
REFERENCES
INTRODUCTION
Sweet potato (Ipomoea batatas) is an important food crop in the
tropical and sub tropical countries and belongs to the family convolvulaceae.
It is cultivated in more than 100 countries. ( Woolfe, 1992). Nigeria is the
third largest producer in the world with china leading, followed by Uganda.
Sweet potato ranks seventh among the world food crops, third in value of
production and fifth in caloric contribution to human diet (Bouwkamp,
1985). Sweet potatoes are rich in dietary fibre, minerals, vitamins and anti
oxidants such as phenolic acids, anthocyanins, tocopherol and ß- carotene.
Besides acting as anti oxidants, carotenoids and phenolic compounds also
provide sweet potatoes with their distinctive flesh colours ( cream, deep
yellow, orange and purple). Sweet potato blends with rice, cowpea and
plantain in nigerian diets. It is also becoming popular as a substitute to yam
and garri. It can be reconstituted into fofoo or blended with other
carbohydrate flour sources such as wheat ( Triticum aestivum) and cassava
( Manihot esculenta) for baking bread, biscuits and other confectioneries
(Woolfe, 1992).
The leaves are rich in protein and the orange flesh varieties contain high beta
carotene and are very important in combating vitamin A deficiency
especially in children.
Sorghum (sorghum bicolor (S. bicolor) is a tropical plant belonging to
the family of poaceae, is one of the most important crops in Africa, Asia and
Latin America. More than 35% of sorghum is grown directly for human
consumption. The rest is used primarily for animal feed, alcohol production
and industrial products ( FAO, 1995). The current annual production of 60
million tons is increasing due to the introduction of improved varieties and
breeding conditions. Several improved sorghum varieties adapted to semi-
arid tropic environments are released every year by sorghum breeders.
Selection of varieties meeting specific local food and industrial requirements
from this great biodiversity is of high importance for food security. In
developing countries in general and particularly in West Africa demand for
sorghum is increasing. This is due to not only the growing population but
also to the countries policy to enhance its processing and industrial
utilization.
More than 7000 sorghum varieties have been identified, therefore there is a
need of their further characterization to the molecular level with respect to
food quality. The acquisition of good quality grain is fundamental to
produce acceptable food products from sorghum. Sorghum while playing a
crucial role in food security in Africa, it is also a source of income of
household . In West Africa, ungerminated sorghum grains are generally used
for the preparation of “to”, porridge and couscous. Malted sorghum is used
in the process of local beer “dolo” (reddish, cloudy or opaque), infant
porridge and non fermented beverages. Sorghum grains like all cereals are
comprised primarily of starch.
The aim and objective of this work is to obtain diet low in sugars, with
enriched nutrients intended for diabetics.
Effect Of Processing Method On The Physio Chemical Properties Of Sweet Potato And Sorghum:
The physicochemical properties of sweet potato and sorghum can be significantly influenced by the processing methods employed. Here’s an overview of the potential effects of processing methods on these two crops:
Sweet Potato:
- Boiling: Boiling sweet potatoes can lead to a loss of some water-soluble nutrients like vitamin C and B-vitamins. However, it can enhance the antioxidant activity of sweet potatoes. The starch in sweet potatoes undergoes gelatinization during boiling, making them softer and more digestible.
- Steaming: Steaming is considered a gentler cooking method compared to boiling. It helps retain more of the water-soluble vitamins and minerals in sweet potatoes. The texture can be maintained, and the natural sweetness is preserved.
- Frying: Frying sweet potatoes can lead to the formation of acrylamide, a potentially harmful compound, due to the Maillard reaction. However, frying can also create a desirable texture and flavor. Balancing the benefits and risks is essential.
- Drying: Drying sweet potatoes can preserve them for longer periods. However, drying at high temperatures can lead to nutrient losses. Proper drying methods can help retain more of the nutrients.
- Milling/Grinding: Processing sweet potatoes into flour can make them suitable for various culinary applications. The milling process might affect the starch structure, which can impact the glycemic index of the resulting products.
Sorghum:
- Milling: The milling process can remove the outer layers of the sorghum grain, which contain fiber and certain nutrients. Depending on the extent of milling, whole grain sorghum products can be more nutritious.
- Fermentation: Fermentation of sorghum can improve its nutritional profile by increasing the availability of certain nutrients, such as B-vitamins and minerals. Fermented sorghum products like sourdough bread or traditional porridges can be more digestible.
- Pearling: Pearling involves removing the outer layers of the sorghum grain. While this can improve the appearance and taste of the final product, it may also lead to nutrient loss.
- Extrusion: Extrusion processing can improve the digestibility of sorghum-based products and create various snack foods. However, high-temperature extrusion can cause nutrient degradation.
- Flaking: Flaking sorghum can produce flakes suitable for breakfast cereals. The process typically involves steaming and rolling, which can impact the starch structure and glycemic response of the product.
It’s important to note that the specific effects of processing methods can vary based on factors such as temperature, duration, and the type of processing used. Also, the nutritional content and quality of the starting raw materials will influence the outcome. To make informed decisions about processing methods, it’s crucial to consider the balance between improving palatability and texture while minimizing nutrient losses.