Production and Evaluation of Tigernut ( Cyperus esculentus ) Milk Flavoured with Moringa oleifera Leaf Extract

Recently, research focus is on phyto - plants with their health benefits. This study therefore was carried out to produce and evaluate quality and acceptability of tigernut milk flavoured with Moringa oleifera leaf extract. Milk was prepared from tigernut and blended with Moringa extract in ratios 95 : 5, 90 : 10 and 85 : 15 respectively while 100 % tigernut milk was used as control. Samples were coded as NOD, MDA, JNJ and ABD respectively. Proximate composition, emulsification, total titratable acidity (TTA), pH and sensory analysis were carried out on the samples. Results showed that sample JNJ had the highest percentages of carbohydrate and protein of 4.33 + 0.02% and 2.34 + 0.02% respectively, ABD had the highest percentages of lipid, ash and emulsifying property of 2.54 + 0.02%, 0.028 + 0.01% and 444 + 4.24 mg/100g respectively. The pH of all samples varies between 7.13 and 7.24. Sensory evaluation showed that sample NOD was the most acceptable. Most of the parameters measured are significantly different (p < 0.05).This study concluded that sample NOD could be produced for consumption and will be acceptable by the consumers. The higher the amount of Moringa oleifera leaf extract added to the imitation milk the better the health benefit it offers. This is because sample


Introduction
In recent years, increased awareness of the health and well being of people globally have necessitated the partial switch from animal-based food products to natural and health foods with nutrient balanced profile required for various metabolic, physiological and other functional demands (Panghal et al., 2009, Panghal et al., 2018. Plant foods are very essential to man's health and survival due to the presence of protein and carbohydrate of about 70% and 80% respectively (Panghal et al., 2006). In addition to this, fruits and vegetable are important plant foods rich in essential vitamins and minerals but are known to have short shelf life due to high susceptibility to physiological breakdown postharvest. To this end, there is need for rapid processing either into shelf-stable or entirely new product to enhance their shelf life as well as value addition .
Tigernut (Cyperus esculentus) is a crop of the sedge family widespread across much of the world. It is an underutilized crop which belongs to the division-Magnoliophyta, Classiliopcida, order -Cyperales and family -Cyperaces (family). It is found in most of the Eastern Hemisphere, including Southern Europe, Africa and Madagascar, as well as the Middle East and the Indian subcontinent and of the same genus as the papyrus plant (Belewu and Belewu, 2007). It is called earth almond, zulu nut. It is known in Nigeria as Aya in Hausa, ofio in Yoruba and Akiausa in Igbo. It has three varieties (black, brown and yellow).The yellow variety is preferred because it yields more milk upon extraction, contains lower fat, less antinutritional factors especially polyphenols and more protein (Okafor et al., 2003).
The tigernut milk is very nutritive and it serves as a source of energy for all categories of people. The nut can be eaten raw, roasted, dried or baked. It is a good source of starch, glucose, protein and minerals such as potassium, phosphorus, vitamin E and C. The tigernut milk fat contains a large amount of oleic acid which is heart friendly and helps to prevent cardiac arrest. It also aids the internal mechanisms and prevents both constipation and diarrhea. (Bamishaiye and Bamishaiye, 2011;Asante, 2014) All parts of the plant are useful and could be used as medicinal plant, vegetable, animal fodder and a source of vegetable oil (Oliveira et al.,1999). The leaves have been reported to havehypocholesterolemic effect (Ghasi et al., 2000), hepatoprotective (Pari and Kumar 2002, Fakurazi and others 2008), antimicrobial (Caceres et al.,1991) and gastric antiulcer effect (Dahiru et al.,2006).
The aim of this study is to evaluate the quality and acceptability of tigernut milk flavoured with Moringa oleifera leaf extract due to the health benefits of Moringa oleifera which has been shown to have crude protein 30%, potassium 1209.67 mg/Kg, iron 26.83 mg/Kg and calcium 1880mg/Kg (Asante, 2014).

Sources of Materials
Yellow tigernut (Cyperus esculentus) (4Kg) was obtained from a market in Badagry Local Government Area of Lagos State, Nigeria, and transported to the Food Technology laboratory, Yaba College of Technology, Yaba, Lagos State Nigeria, in a thick polyethylene bag for processing. These were divided into four batches of 1kg each. Moringa oleifera leaves (2Kg) which were healthy and uninfected were obtained from the college campus and taken to the laboratory same day. The leaves were washed under running tap to remove dust and other foreign particles.

Production of Tigernut Imitation Milk and Moringa oleifera Extract
The imitation milk from tigernut was produced by modifying the method of Adgidzi et al.,(2011). The batches of fresh tiger nut samples were cleaned and soaked in cold water for 24hrs, wet milled with about two litres per kilogram of water, using a clean sterilized blender. This was followed by filtration using muslin cloth to remove the chaff from the milk.
Fresh leaves of Moringa oleifera (1Kg) was boiled with 1.5 litres of water for 15 mins at 80 0 C, after which it was cooled. The extract was separated using sterile muslin cloth and filter through sterile Whatman filter paper.

Production of Tigernut -Moringa oleifera Milk
After the production of milk and moringa extract, different blending ratios of 95 ml of tigernut milk to 5ml of moringa extract, 90ml of tigernut milk to 10ml of moringa extract, 85ml of tigernut milk to 15ml of moringa extract were produced while 100ml of tigernut milk was prepared as control. These samples were coded NOD, MDA, JNJ and ABD respectively.

Proximate Analysis
The moisture content, fat, protein, crude fibre and crude ash of the samples were determined using the methods of AOAC (2005) while carbohydrate was calculated by difference as highlighted by AOAC (2005) as; % carbohydrate = 100 % -% (moisture + protein + fat + fibre + ash).

Titratable Acidity, pH and Emulsification Property.
Titratable acidity and pH were determined by the methods of Nout et al. (1989). A standardized pH meter (OHAUS, Starter 2000) was used to determine the pH after it has been standardized with buffer at pH 4 and 7. Mineral elements (Ca, Mg, K, Na) were estimated as described by Fernandez (2002) using Atomic Absorption Spectrophotometer (A. Analyst 700, Perkin Elmer, USA) equipped with standard burner air-acetylene flame and hollow cathode lamps, as radiation source. Emulsification capacity was determined using the modified method of AOAC (2000).

Sensory Evaluation
Samples were assessed for colour, flavour, taste, aroma and overall acceptability using a 20 -member semi -trained panelists on 9 -point hedonic scale with (9) = extremely like and (1) = extremely dislike. The samples were presented to the panelists using white glass cups. This was as described by Larmond (1977).

Statistical Analysis
The mean scores were analyzed using analysis of variance (ANOVA) and differences separated using Duncan test. SPSS 15.0 software package was used to run the analysis.

Results and Discussion
The results of the proximate analysis of the samples were shown on Table 1. The results showed that the carbohydrate and protein contents were highest in sample JNJ (85:15 tigernut -moringa) and lowest in ABD (control sample) and MDA (90:10 tigernutmoringa) respectively. Lipid, moisture and crude ash contents were highest in sample ABD and lowest in sample MDA and JNJ respectively while crude fibre was highest in sample MDA and lowest in sample ABD. All the samples analysed generally have high carbohydrate contents with the values ranging between 2.07 -4.33%. The highest carbohydrate content in sample JNJ was due to high carbohydrate content of tigernut milk and moringa extract.
Tigernut milk has been reported to be used in the treatment of flatulence, indigestion, diarrhea and dysentery due to its carbohydrate content (Bixquert -Jimenez, 2003). In addition, starch content of this product has been reported to provide probiotic properties for colon bacteria (Alegria -Toranand  et al. (2012). The product required cold storage to prevent deterioration due to its high moisture and fat content. There were significant differences in the proximate composition measured except for protein and ash.
The results of pH and total titratable acidity (TTA) are shown in Table 2. It was observed that sample ABD has the highest pH (7.24) and lowest TTA while sample JNJ has the lowest pH (7.13) and sample MDA has the highest TTA (0.48). These pH values were within neutrality and were similar to   The results for the mineral content were shown in Table 3. Magnesium, potassium, phosphorus, sodium and calcium were highest in sample ABD, followed by sample JNJ and lowest in sample MDA. Tigernut has been reported to be a very good source of some useful minerals including potassium, phosphorus and calcium (Bixquert -Jimenez, 2003). This result is due to the fact that moringa oleifera is also known to be rich source of these minerals (Asante et al., 2014) The results of the sensory evaluation in Table  4 showed that sample NOD has the highest mean values for taste, flavour, aroma and overall acceptability among the test samples when compared with the control sample (ABD).High sensory values obtained for sample ABD maybe due to the familiarity of the panelists with products from tigernut milk. There was no significant difference at (p < 0.05) in terms of colour. JNJ has the lowest values in terms of taste, flavour, aroma and overall acceptability. There were significant differences between the control samples and the experimental samples in the sensory parameters evaluated.
The most acceptable blend in terms of sensory evaluation was sample NOD (95:5 tigernut -moringa) which had the highest mean scores in the sensory parameters assessed.

Conclusion
In this study, milk from control sample had the highest mineral content while sample JNJ had the highest carbohydrate and protein contents. Sample MDA had the least values for all these parameters measured. It was observed from the study that the experimental samples are significantly different This study concluded that sample NOD could be produced for consumption and will be acceptable by the consumers. The higher the amount of Moringa oleifera leaf extract added to the imitation milk the better the health benefit it offers. The results from the proximate and mineral composition showed that sample JNJ (85:15 tigernut -moringa) has the highest nutrients. This is due to the fact that the sample has the highest amount of moringa oleifera which in addition to tigernut is a rich source of protein, digestible carbohydrate and minerals.

Conflict of Interest
Authors declare that no conflict of interest.