Biochemical composition of Philippine Mulberry (Morus spp.) fruits

Introduction

Mulberry or 'Amoras' in the Philippine dialect is ofgenus Morus belonging to the Moraceae family. It is adeciduous tree grown in various temperate areas of theworld. It grows to about 3.5 meters high, leaves areovate and flowers are unisexual. Fruiting spikes areaxillary, peduncled, dark purple or nearly black whenripe, fleshy, and 1.5 to 3 centimeters long. They arewind pollinated and some cultivars will set fruitwithout any pollination. The fruits yield 30% fat, andother substances like sugar, pectin, citrates andmalates.

Mulberries have a sweet, juicy and refreshing taste. Itis highly appreciated for its sweet and unique fruitflavor and abundant composition of nutrients. Thereare dozens of mulberry species and they range incolor, shape, and taste. 

Mulberry fruits have a remarkable place in traditionalChinese medicine and have been used to treat sorethroat, cure fever, prevent liver damage, strengthenthe joints, facilitate discharge of urine, and lowerblood pressure (Lui et al., 2004; Li et al., 2009), treattinnitus, dizziness, constipation in the elderly andanemia (Li et.al., 2009; Chang et al., 2011; Wang etal., 2013). Its medicinal worth is attributed to thepresence of active ingredients with notabletherapeutic functions (Ercisli & Orhan, 2007), ascited by Sivakumar et al. (2015).

Studies revealed that mulberry fruits contain not onlyappreciable amounts of proteins, carbohydrates, fats,fibers, mineral contents, and some vitamins, but alsomany bioactive compounds such as anthocyanin,flavonoids, and alkaloids (Onose et al., 2013). Ercisli andOrhan (2007) accounted that mulberry is rich inanthocyanin compounds, and identified the majoranthocyanins in the fruit extract. Anthocyanins werereported to have therapeutic benefits and areresponsible for the color attribute and biologicalcharacteristics such as antioxidant, anti-proliferative,antimicrobial, anti-cancer, and anti-neoplasticproperties as well as neuroprotective and antiinflammatory properties (Liang et al., 2012). Mulberryhas also been known to be rich in 1-deoxynojirimycin(DNJ) which inhibits postprandial hyperglycemia byinhibiting alpha-glucosidase in the small intestine(Asano et al., 2001; Gui et al., 2001). It has anti-virus(Durantel et al., 2001; Lazar et al., 2007); and antitumor (Lou et al., 2011) activities, and modestlydecreases serum triglyceride (TG) level in human(Kojima et al., 2010), as cited by Sivakumar et al. (2015). 

To date, the Sericulture Research and DevelopmentInstitute (SRDI) has evolved mulberry varieties thatwere considered high leaf-yielding for the silkworms.Fruit-bearing varieties were also developed for theproduction of other products. However, the fruits arenot utilized efficiently, especially during the peakseasons of the year like dry (March) and wet (July)where most of the fruits are wasted since mulberries,specifically the leaves are intended for silkworm food. 

Further, mulberry fruit product consumption hasbeen rapidly increasing because of biological benefits,nutritional value, and taste, (Aramwit et al., 2010), ascited by Raman et al. (2015).

Given the above-mentioned biochemical componentsof the mulberry fruit and its beneficial and nutritionalvalue, the result of the study can serve as a basis forfurther tests on the possibilities of using the varietiesin the pharmaceutical industry thereby makingmoriculture a potentially profitable enterprise. Thiscan be a means to uplift the living status of thesericulture farmers and clients in the community.Moreover, it can help sustain product diversificationinitiatives of the institute such as wine and vinegarproduction. The resulting data on the biochemicalcomponents of the mulberry varieties studied willserve as an important basis for the formulation andstandardization of the products produced. The highcontent of biochemical compounds in the mulberryfruit pave for the development of industrial functionalfood drinks such as puree or mulberry juice andsmoothies; candies out of dried mulberry fruits,mulberries, ice cream and coated mulberry fruit (darkchocolate). Therefore, this study initially evaluatednew genotypes with better biochemical characteristics-the most important quality criteria of mulberryfruits, provides vital information necessary to strengthen and promote the industrialization andcommercialization of mulberry fruit products, couldhelp develop an improved understanding andappreciation of the nutraceutical and medicinal valueof mulberry fruit which in turn could promote itsconsumption by the general public. Furthermore, topromote the value addition of mulberry, it isimperative to characterize the fruit traits from thechemical point of view as well as to enable them to fitinto current processing industry requirementsexample superior qualitative and sensorial propertiescombined with higher contents of health-promotingbioactive compounds (Donno et al., 2015) as cited byKrishna (2018).

The experiment determined the biochemicalcomposition of five mulberry fruiting varieties for ash,moisture content (MC), crude protein (CP), crude fat(CF), total carbohydrates (TC), sodium, sugar, pH,anthocyanin, Vitamin C and Titratable acidity (TA)during the dry and wet seasons and to identify thebest variety with the highest biochemical contentsduring the dry and wet seasons.