In ternationa l Scholars Journa ls African Journal of Food Science Research ISSN 2375-0723 Vol. 6 (8), pp. 352-355, August, 2018. Available online at www.internationalscholarsjournals.org © International Scholars Journals Author(s) retain the copyright of this article. Full Length Research Paper A study of the mineral concentration of some Nigerian packed fruit juices, concentrate and local beverages Dosumu O. O., Oluwaniyi O. O.*, Awolola G. V. and Okunola M. O. Department of Chemistry, University of Ilorin, P.M.B. 1515, Ilorin, Nigeria. Accepted 17 March, 2018 Time stability and mineral content of some Nigerian packet fruit juices, concentrate and local beverages (sobo drink, kunnu drink, pito and burukutu ) were determined. The pH of the beverages was fairly stable throughout the 15 days the experiment lasted. The acid contents were within suitable range for human consumption and ranged from 0.041 M – 0.205 M. The concentrate has the highest titratable acidity ranging from 0.098 M on day 1 to 0.205 M on day 15. Elemental analysis of the minerals showed that the beverages were rich in macronutrients. Potassium was found to be the most abundant with content ranging from 4.35 – 5.85 mg/mL while manganese and copper were not detectable. Sodium content was between 1.300 – 1.335 mg/mL; calcium 0.560 – 0.925 mg/mL; magnesium 0.005 – 0.06 mg/mL; iron 0.005 – 0.025 mg/mL and zinc 0.005 – 0.010 mg/mL. The results showed that the drinks contain safe levels of mineral elements for human consumption and are sufficiently stable and safe. Key words: Stability, fruit juices, beverages, concentrate, mineral content. INTRODUCTION If the importance of a nutrient is judged by how long we can do without it, water ranks as the most important. A person can survive only eight to ten days without water, whereas it takes weeks or even months to die from a lack of food. While water has no caloric value and therefore is not an energy source, without it in our diets we could not digest or absorb the foods we eat or eliminate the body’s waste. Water is replenished by drinking liquids like fruit juices and beverages, preferably those without caffeine or alcohol, both of which increase the output of urine and thus dehydrate the body (Worthington-Roberts, 2007). Various types of drinks/beverages are often consumed as sources of fluids. Fruit juices are directly extracted from fruits and con- sumed without further processing. Some of these are packed in bottles or laminated papers and sold. Fruit dri- nk concentrates are a concentrated form of the juice ext- racted from natural fruits. Since it is expensive to pack- age and store single strength juice, it is often desirable to remove a part or all of the water from the juice (Kim et al., *Corresponding author. E-mail: laraoluwaniyi@yahoo.com. 1988). Such concentrates are diluted with water prior to consumption. Concentration reduces the storage volu-mes, thereby reducing the transport costs, and facilitates preservation which is achieved by improved shelf life with increased relative solid concentration. However during the process of concentration, a large part of the characte-ristics determining the quality of the fresh products under-goes remarkable modification which could reduce the nutritional value of the drink (Hur and Choi, 1993; Lee and Sohn, 2003; Choi et al., 1995). Fruits have been a part of human diet and food supple- ment over the years. They are considered as healthy food supplements because they contain high quantity of water, carbohydrates, proteins, vitamins A, B1, B2, C, D and E; and minerals such as Ca, Mg, K, Zn and Fe (Wenkam, 1990; Okwu and Emenike, 2006). Besides their dietary importance, they are also useful as nutrient supplements and recommended internationally as supe-rior to processed foods (Wenkam, 1990). Fruit consump-tion has been reported to be beneficial to health and to contribute to the prevention of degenerative processes, particularly lowering the incidence and mortality rate of cancer and cardio- and cerebro- vascular diseases (Rapi- sararda et al., 1999). Dosumu et al. 353 Table 1. pH variation of Beverages over 15 days. Beverage pH Values / Days Samples 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 FOJ 3.2 3.1 3.3 3.2 3.2 3.1 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.1 3.1 COJ 3.9 3.7 3.6 3.7 3.7 3.6 3.7 3.6 3.5 3.4 3.4 3.4 3.4 3.3 3.3 BOC 2.6 2.6 2.7 2.7 2.7 2.6 2.7 2.6 2.4 2.4 2.4 2.4 2.4 2.1 2.1 SD 2.8 2.8 2.7 2.7 2.7 2.7 2.6 2.6 2.6 2.6 2.5 2.6 2.6 2.6 2.3 KU 3.3 3.0 2.9 2.8 2.7 2.7 2.7 2.7 2.7 2.5 2.5 2.5 2.4 2.4 2.3 PT 3.7 3.7 3.6 3.6 3.5 3.4 3.0 3.0 2.9 3.0 2.9 3.0 2.9 2.8 2.8 BK 3.4 3.3 3.3 3.5 3.7 3.4 3.1 3.0 2.9 3.1 3.0 3.0 2.9 3.0 3.0 Apart from fruit juices and concentrates, other plant materials are often used in the preparation of alcoholic and non-alcoholic beverages. The simplicity of produc- tion, availability of raw plant materials and abject poverty in many rural communities, as well as the new economy- revamping policies of the government have resulted in increased production and consumption of many local beverages at cottage levels in Nigeria. Sobo drink and Kunnu drink are ready local alternatives to imported refre- shing drinks. They are also reported to have various me- dicinal values (Onoja, 1996). Sobo drink is an aqueous extract of the dried reddish-brown petals (calyxes) of Hi- biscus sabdariffa which is usually sweetened with sugar and sometimes flavoured with spices like ginger, hot pep- per etc along with natural flavours like pineapple, orange or lime juice (Odebunmi and Dosumu, 2007). Other artifi- cial flavourings like strawberry, vanilla, banana flavours etc, may also be added depending on individual taste (Bola and Aboaba, 2004). Kunnu is a drink made from ground millet or/and guinea corn and it is basically a refreshing, non-alcoholic drink. Pito and Burukutu are loc- ally brewed alcoholic drinks from ground and fermented millet or/and guinea corn. Pito is the liquid part that floats while Burukutu is the part that settles in the bottom with some sediment in it. In spite of the high consumption rate of these bevera- ges, their stability and nutritional quality are not well do- cumented. This work therefore aims to examine and pro- vide information on the keeping qualities as well as the mineral composition of some of these drinks. EXPERIMENTAL Two popular brands of orange juices packed in laminated paper were used in this study and labelled FOJ and COJ. A fruit drink con- centrate was also used (BOC) while the local beverages used are Sobo drink (SD), Kunnu (KU), Pito (PT) and Burukutu (BK). FOJ and COJ represent the ready-made fruit juices and were purchased from a store within Ilorin metropolis, BOC is a concentrate that is diluted before consumption and was also purchased from a store, SD and KU were locally-prepared non-alcoholic beverages while PT and BK are alcoholic local beverages and they were obtained from local brewers. All samples were kept in sample bottles with tight- fitting lids and kept at room temperature. Stability studies The stability of the samples was monitored by measuring the pH at 25°C for 15 days at 24 h intervals. The acidity was also determined by titrating 10 ml of samples with 0.1 M NaOH solution using 1% phenolphthalein as indicator. The titration was carried out on a daily basis for a period of 15 days. Mineral content determination Each drink sample was digested by the wet ashing method prior to mineral content determination as described by Abulude et al. (2007). 1 ml of sample was measured into a beaker and 10 ml of 1% HCl was added and the mixture heated on a hot plate until the content was reduced to about 1 ml. The solution was then made up to 50 ml with 1% HCl and stored in plastic containers until analyzed for K, Na, Ca, Mg, Mn, Fe, Cu and Zn using atomic absorption spectrophotometer. RESULTS AND DISCUSSION The pH values obtained for all the drinks ranged between 2.1 and 3.7 (Table 1) and there was an observed gradual reduction in the pH values as the days progressed (Figure 1) except for BK which increased slightly until day 5 after which there was a steady decrease in the pH. This could imply that the samples were becoming more acidic and therefore less susceptible to bacterial action but more susceptible to the action of yeasts and moulds (Adeyeye and Agesin, 1999). The samples were also observed to develop characteristic ‘fermented’ smell as the days progressed. This may be as a result of the fermentation of the drinks to alcohol and then to vinegar due to the action of yeasts. FOJ had relatively constant pH values (3.1 – 3.3) compared with other samples and BOC had the lowest pH values (2.1 – 2.7). The results of the titratable acidity of the beverages presented in Table 2 shows that the different beverages behaved differently as the days progressed. Generally, the highest titratable acid concentrations were obtained in the packed juices (FOJ and COJ) and burukutu. The acid content of FOJ was observed to gradually increase as the days progressed until after 5 days when the concen- tration started reducing gradually to a minimum concen- 354 Afr. J. Food Sci. Res. Table 2. Titratable acidity (M) of the beverages. Days Titratable Acidity (M) FOJ COJ BOC SD KU PT BK 1 0.111 0.098 0.068 0.041 0.071 0.060 0.100 2 0.111 0.101 0.066 0.042 0.071 0.062 0.091 3 0.109 0.103 0.065 0.043 0.080 0.065 0.090 4 0.109 0.111 0.067 0.044 0.085 0.075 0.087 5 0.128 0.128 0.068 0.044 0.090 0.077 0.086 6 0.125 0.132 0.066 0.043 0.102 0.090 0.097 7 0.121 0.132 0.066 0.047 0.104 0.092 0.101 8 0.120 0.134 0.064 0.048 0.108 0.095 0.105 9 0.119 0.138 0.063 0.048 0.105 0.115 0.111 10 0.114 0.137 0.064 0.049 0.111 0.117 0.118 11 0.113 0.137 0.064 0.049 0.112 0.126 0.132 12 0.111 0.144 0.064 0.050 0.114 0.136 0.143 13 0.106 0.153 0.065 0.053 0.117 0.147 0.148 14 0.105 0.204 0.063 0.054 0.120 0.156 0.154 15 0.101 0.205 0.063 0.056 0.123 0.159 0.158 Figure 1. pH Values of Beverages over a period of 15 days. Figure 2. Variation in titratable acidity of beverages over 15 days. tration of 0.101 M. The other packed juice exhibited different characteristics with the concentration increasing gradually from the 0.098 M on day 1 to 0.205 M on day 15. BOC which is a concentrate showed a fairly constant titratable acidity (0.063 – 0.068 M). This is expected since the concentrate contains some preservatives which are expected to inactivate the enzymes in the drink and therefore prevent the deterio-ration or any chemical reaction in the drink (Fellers et al., 1986). Sobo drink has the least titratable acid concentrations (0.041 – 0.056 M) and these increased gradually as the number of days increased. KU and PT also showed incr- easing acidity as the experimental days increase while BK recorded a slight decrease in the acidity during the first 5 days and then a continual increase during the rest of the days which was attributed to the breakdown of the natural antioxidants and antimicrobial agents. The mineral compositions of the beverages are shown in Table 3. Potassium is the most abundant element in all the beverage samples followed by sodium and then cal- cium. Copper and manganese were not detectable in the beverages while magnesium, iron and zinc are pre- sent in trace amounts. This result is in agreement with the result reported by Onibon et al. (2007) who worked on some Nigerian fruits and also reported that potassium was the most abundant mineral in the fruits while mag- nesium, iron and zinc were present in minute quantities the Potassium and sodium are macroelements required Dosumu et al. 355 Table 3. Mineral Composition (mg mL -1 ) of the beverage samples. Beverage Mineral Composition (mg mL -1 ) Samples K Na Ca Mg Fe Zn Mn Cu FOJ 5.100 1.305 0.730 0.010 0.010 0.010 ND ND COJ 5.850 1.320 0.925 0.005 0.025 0.005 ND ND BOC 5.215 1.300 0.805 0.005 0.010 0.010 ND ND SD 4.750 1.305 0.875 0.010 0.015 0.005 ND ND KU 4.850 1.320 0.595 0.010 0.010 0.005 ND ND PT 4.350 1.300 0.640 0.005 0.010 0.010 ND ND BK 5.550 1.335 0.560 0.060 0.005 0.005 ND ND ND = Not detectable. for the maintenance of cellular water balance, acid-base balance and nerve transmission and are required in large amounts in the body (Wardlaw, 1999; Worthington-Rob- erts, 2007). Deficiencies of these macronutrients lead to muscle cramps, mental confusion, loss of appetite and ir- regular cardiac rhythm (Worthington-Roberts, 2007). However, there is a direct relationship between sodium intake and hypertension in humans (Dahl, 1972) there- fore it is desirable that the concentration of sodium in foods is not as high as that of potassium. These results therefore indicate a desirability of the consumption of these beverages because they contain a high concentra- tion of sodium and potassium but the concentration of sodium is lower than that of potassium. Calcium is ess- ential in bone and teeth formation (Wardlaw, 1999) and a deficiency of it causes rickets and osteoporosis (Hunt et al., 1980) . Consumption of these beverages is therefore desirable as they serve as good sources of this macro- nutrient. Conclusion This work has shown that except for COJ (a packed fruit juice) and BK (a local alcoholic beverage), the beverages have fairly stable titratable acidity throughout the days of the experiment and the acid contents are suitable for con- sumption even without refrigeration. The shortcoming is the ‘alcoholic smell’ emanating from the drinks due to fer- mentation as the days of the experiment progressed. This was because the drinks were kept at room temperature. 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