Value addition of mulberry fruits

Introduction

Mulberry (Morus alba L.) a generic name of Morus has been derived from Latin word "Mora", which means delay (Janick and Paul, 2006) [33] . Morus genus has about 68 species of trees and shrubs throughout the world. This genus is widely distributed in Asia, Africa, Europe, South and North America. It is also widely found in hilly areas of Himalayas up to 3300 m elevation (Zafar et al., 2013) [34] . Among various Morus species, Morus alba L. has been cultivated widely in Asia especially in China, Japan and India for rearing silkworms besides fruit purpose. Other species like M. indica, M. serrata and M. laevigata are also found in India (Ravindran et al., 1997) [35] . Fruits of this species are long, ovoid or cylindrical, which are variable in colour like white, pink or purple to black. The fruit yield increases with tree size and a fully grown tree can yield between 10-15 Kg fruits (Sharma and Zote, 2010) [36] . Mulberry fruit is full of anti-aging properties and enriches the blood, protecting liver from damage, calms the nerves, balances internal secretions and enhances immunity. Only the scattered information is available in the literature and no systematic work has been done regarding the use of its fruits for the production of value added products. So keeping in mind its availability and importance with respect to various quality characteristics, this paper aims to summarize recent knowledge regarding the value addition and their health benefits of mulberry fruit. This review may be useful for predicting other health benefits and potential drugs and may encourage new research and relevant industries to more deeply explore mulberry fruit in the future.

Physico-chemical characteristics of mulberry fruit 1. Physical characteristics

Characteristics

Content Reference

Fruit weight

Morus alba 0.66 -3.49 g Iqbal et al.2010; Zengin et al.2012 [10,32] .

Morus nigra

1.13 -5.67 g Koyuncu et al.2004; Dwivedi and Pathak 2012 [12] Seed Morus nigra 3.90% Dwivedi and Pathak 2012 [12] .

Colour

Variable in colour (white, pink, red, blue, purple and black) Kumaresan et al.2008 [13] Size Diameter (cm) Length (cm) [8] Cyanidin-3-O-glucoside(C3G)(mg/g) ND 8.22 -Chen et al. 2017 [4] Cyanidin-3-O-rutinoside(mg/g) ND 2.86 -Chen et al. 2017 [4] Pelargonidin-3-O-glucoside(mg/g) ND 0.25 -Chen et al. 2017 [4] Total phenolics (mg GAE/100 g) 181 1422 1035 Ercisli et al. 2007 [8] Total flavonoids (mgGAE/100 g) 29 276 219 Ercisli et al. 2007 [8] Cyanidin-3-O-glucoside(C3G)(mg/g) ND 8.22 -Chen et al. 2017 [4] Cyanidin-3-O-rutinoside(mg/g) ND 2.86 -Chen et al. 2017 [4] Pelargonidin-3-O-glucoside(mg/g) ND 0.25 -Chen et al. 2017 [4] Quercetin-3-O-rutinlside(mg/g) 0.08 0.45 -Chen et al. 2017 [4] Quercetin-3-O-rutinlside(mg/g) 0.08 0.45 -Chen et al. 2017 [4] Nutraceutical and Medicinal Properties Sr.

Biological activity Findings References 1

Anti-diabetic activity

Ethyl acetate-soluble extract of mulberry showed decrease in the fasting glucose and glycosylated serum protein levels of diabetic rats (fed for 2 weeks). Mulberry anthocyanin extract (50 and 125 mg/kg body weight per day) fed for eight weeks was effective in reducing the fasting blood glucose levels of male C57BL6/J genetic background type-II diabetic mice Diabetic rats fed with Mulberry Fruit Polysaccharide-MFP50 and MFP90 ethanol Extract for seven weeks showed 26.5% and 32.5% decrease in serum insulin levels respectively. Significant decrease in levels of fasting glucose and serum insulin, and triglyceride was observed. [4] 3 Hyperglycemic activity Mulberry fruit extract was found more effective among bilberry and blackberry fruit extracts in decreasing the glucose level when given to Ştefănuţ et al.,2013 [24] Diabetic rats in drinking water for five weeks.

Anti-obesity action

High-fat diet-induced obese mice fed with a combination of mulberry leaf extract and mulberry fruit extract at low and high doses (133 mg MLE and 67 mg MFE/kg/day) and (333 mg MLE and 167 mg MFE/kg/day) respectively for 2 weeks significantly showed anti-obesity action as it resulted in decrease in body weight gain, fasting plasma glucose and insulin, adipocyte size. Mulberry water extract (MWE) showed anti-obesity action on male hamsters by lowering the high-fat diet-induced body weight, visceral fat, serum and liver lipids. The MWE maintains lipolysis and lipogenesis thus helps in weight loss. Mulberry anthocyanins were introduced in Daily diet of mice fed with high fat diet, Showed inhibition in weight gain, reduced the adipocytes size and impaired lipid accumulation.

Peng et al, 2011 Wu et al, 2013 Lim et al,

Hyper-lipidemic action

Water extracts showed lipid lowering effects by diminishing its biosynthesis and increasing the LDLR gene.

Liu et al, 2009 [17] 6 Antioxidant activity

Destruct the damaging oxidative substances in RBC. 70% ethanol extract was successful in giving the protective results in the protective action of mulberry fruit in H2O2-induced oxidative injury of pancreatic MIN6N beta-cells at a concentration of 400µg/mL. Mulberry Fruit Polysaccharide i.e. MFP3P-Se (selenide of Polysaccharide) exhibited higher peroxyradicals-scavenging capacity than MFP3P in vitro.

Yan and Zheng, 2017 Hong et al., 2004 [30] 7 Hypolipidemic activity 5% or 10% mulberry powder was supplemented with high fat diet oral showed significant increase in the HDL levels thereby decreasing the LDL, liver triglyceride and total cholesterol levels. This is due to the presence of high linoleic acid and dietary fiber content in the fruit. High cholesterol diet with 0.5% and 1.0% mulberry fruit (water extract) was given to New Zealand white rabbits, significantly decreased cholesterol (total and LDL) levels, triglycerides and reduced severe atherosclerosis. 45 g freeze-dried mulberries were consumed by hyper-cholesterolemic Adults (30-60yrs), after 6 weeks they showed lower levels of cholesterol (total and LDL). [21] 9 Anticancer action Anthocyanin-rich mulberry fruit extract given to male bal b/c nude mice for seven weeks, showed inhibition in atypical glandular cells (AGS) tumour xenograft growth thus preventing gastric Carcino maformation

Huang, Chang, Wu, Hung and Wang, 2011 [3,9] 10

Butyl pyro glutamate, a bioactive compound was extracted from mulberry fruit has a protective effect against cisplatin-induced kidney cell damage Lee et al., 2018 [14] 11 Anti viral activity 0.005% and 0.25% mulberry juice was found effective on reducing the infectivity of murine norovirus-1 (MNV-1) and feline calicivirus-F9 (FCVF9) respectively. 0.1% juice was effective enough for inhibition of viral replication (60% reduction).

Lee, Bae, Oh, Kim and Chung, 2014 [15] 12

Cytoprotective action

Polysaccharides extracted from fruit protects the cells of the pancreas by inactivation of certain components such as Bcl-2, Bax, JNK, p38, and caspase-3 responsible for causing apoptosis. Jiao et al., 2017 [11] Economic uses of mulberry fruits Mulberry is grown worldwide. Its leaves are used to feed the silkworms which in turn produce silk fiber. Besides using the leaves, mulberry bears sweet fruit. The full-bodied flavor of this fruit is a good balance of sweetness and tastiness with nutrient elements of vital importance for human metabolism. If these fruits are industrially exploited for various commercially valuable products, mulberry can become an important crop throughout the world. Mulberry can be used for making jam, jelly, pulp, fruit drink, fruit sauce, cake, fruit tea, fruit powder, fruit wine, food colorant, diabetes control agent and as ruminant livestock feed. It can also be used in the pharmaceutical industry. It opens a new vista for industrial exploitation of mulberry fruits worldwide. Such a use of the mulberry has been overlooked for the sake of using only mulberry leaf for the sericulture industry.

Mulberry fruit in the preparation of jams, jellies and sweet products:

Mulberry is basically a source of delicious fruit and popular among many countries of the world. Mulberry fruit contains high sugar content and hence used in the preparation of jams, jellies and other sweet products. In recent years, with considerable work on cultivating mulberry plants under various conditions, mulberry fruit juice has been commercially produced as a health beverage, and it has become very popular in China, Japan and Korea. Without adding preservatives, the original juice of mulberry fruit remains fresh under cold storage for 3 months, while the bottled beverage remains fresh at room temperature for about 12 months (Dharmananda, 2008) [5] . From one acre of mulberry tree cultivation; which has a spacing of 8 x 9' between tree to tree and row to row, about 1993 kg of fruit jam and 2794 liters of fruit pulp can be prepared in sub-tropical India. The market survey revealed an income of 1063.72 US $ and 1161.70US$fromthesaleofjam and pulp, respectively in Indian markets (Singhal et al., 2009a b) [22] . Mulberry fruits are used fresh, dried or frozen in the food industry to obtain different syrups, tonic wine, amaretto or vermouth wine, vinegar and different sweet products (marmalade, chocolate, frosting, jelly and fondant), oil from mulberry seeds. Mulberry fruit juice it is also used as natural alcoholic extract additive for food and pharmaceutical industries. From the mulberry fruits after alcoholic fermentation and further distillation it is made a perfect hard alcoholic drink. Mouro is the spirit beverage that comes from the distillation of fermented fruits of the mulberry tree (Morus nigra L.). Mouro is also the Greek common name of this fruit. Usually, it is used for the production of syrups, jams and jellies.

Mulberry fruit in the preparation of wine

Mulberry fruit is having high content of vitamin C hence is commonly used for the preparation of special wine and beer in most of the temperate countries. Over-ripened and sour fruits can be converted into mulberry wine (Ehow, 2009) [7] . The wine has a sweet and sour taste. A glass of mulberry wine a day helps get rid of impurities and coprostasis (fecal residue in the intestines) in the body which can help make the body slim. The wine made by immersing the mulberry in rice wine or grape wine works as medicine for weakness after diseases that can also be used to notify masculine vitality and benefit overall vitality. In Azerbaijan, Georgia and Armenia, a potent liqueur "Tut araghi" made from mulberry fruit juice is very popular. It is one of the national Azerbaijani versions of vodka. It is believed that small dose of the drink protects against stomach and heart diseases. In Greece, mulberry fruits are used for the production of the traditional aromatic mouro distillate. Soufleros et al., (2004) [23] standardized the production process of mouro distillate for its safe use as an alcoholic beverage. Mulberry fruit wine is very popular among ladies as a ladies drink in Europe.

Glass of mulberry wine a day helps get rid of impurities and coprostasis (fecal residue in the intestines) in the body which can help make the body slim. The wine made by immersing the mulberry in rice wine or grape wine works as medicine for weakness after diseases that can also be used to notify masculine vitality and benefit overall vitality. In Azerbaijan, Georgia and Armenia, a potent liqueur "Tut araghi" made from mulberry fruit juice is very popular. It is one of the national Azerbaijani versions of vodka. It is believed that small dose of the drink protects against stomach and heart diseases. In Greece, mulberry fruits are used for the production of the traditional aromatic mouro distillate. Soufleros et al., (2004) [23] standardized the production process of mouro distillate for its safe use as an alcoholic beverage. Mulberry fruit wine is very popular among ladies as a ladies drink in Europe.

Mulberry fruit as a natural food colorant

Mulberry fruits are rich in anthocyanins and deserve to be exploited for the industrial production of natural color to be used in the food industry. In particular, it is known to contain cyanin, which contributes the red pigment that gives the fruit a red to purple color. The major anthocyanins found are cyaniding-3glucoside and cyaniding-3-rutinoside. These pigments hold potential for use as dietary modulators, mechanisms for various diseases and as natural food colorant (Wrolstad, 2001) [28] . As synthetic pigments are unsafe, there is a demand for natural food colorants in the food industry. Since these are water-soluble, they are easily extractable and incorporated into the aqueous food systems. A cheap and industrially feasible method to purify anthocyanins from mulberry fruit has already been established (Liu et al., 2004) [17] which could be used as a fabric tanning agent or food colorant of high color value. It is found that out of 31 Chinese mulberry cultivars tested, the total anthocyanin content varies from 148 mg to 2725 mg per liter of fruit juice. Total sugars, total acids and vitamins remain intact in the residual juice which can be used for pulp and wine preparation. However, anthocyanin content depends upon the climate of the area of cultivation. Anthocyanin content is particularly high in dry Tropical sericulture countries could make quite a good profit with the industrial production of anthocyanins from mulberry fruits.

Mulberry fruit as a feed supplement to livestock Habib (2004) has reported that a multi-nutrient feed block prepared from mulberry fruits has increased milk production from 30% to 50% in livestock with low disease incidence. It is found that a farmer can earn about US$17-26 per month during the mulberry season rom commercial preparation of mulberry fruit blocks. It is mentioned that the technology of utilizing mulberry fruits as feed blocks for animals can be exploited as an income-generating micro enterprise.

Dyeing cotton fabric with anthocyanin dyes from mulberry fruits:

The natural anthocyanin dyes (mainly consisting of cyanidine 3-glycoside) extracted from mulberry (Morus rubra) fruits has been successfully used to dye cotton fabric, with a dyeing property performance good enough for potential commercial applications. In this study, succinic acid was firstly incorporated into cotton fabrics by esterification to the hydroxyl groups of cellulose, forming an anionic site for the dyes. The anthocyanin extracts from mulberry fruits were used to study the dye ability of the control and modified cotton fabrics. Red and deep purple (aubergine) are two main shades of cotton fabrics dyed with mulberry fruit extracts. The colour strength of dyed cotton fabric was improved from 2.7 to 5.3 in the case of dyeing without mordants, and from 3.2 to 6.9 in the case of dyeing with tin mordanting. Meanwhile, the colour fastness was improved by 0.5-2 grades with increasing succinic acid concentration in the finish solution.

The colour fastness to perspiration, crocking, light, and washing of fabric dyed with simultaneous tin mordanting and modified with 30g of succinic acid was found to be acceptable, with a grey scale grade of at least 3. As for home laundering, neutral soapy solution was more acceptable than alkaline soapy solution.

Recent utilization of mulberry fruit products

S. No Mulberry fruit products Key findings

Wine Various mulberry accessions were used for wine production. MI-497 was best suited mainly because of its deep red color and retained physicochemical and sensory properties (Yadav, Garg, & Kumar, 2017) [29] .

Jelly

Jelly was prepared by using various juice-sugar combinations and the best-suited combination was of 50% juice and 45%. Most of physiochemical, quality and sensory characteristics were retained in this particular combination at refrigerated condition (Thakur, 2016) [26] .

Biscuit and Bread

Dry fruit and fruit powder (colouring agent and to enhance anthocyanin content) of Morus nigra was used for the preparation of biscuits and breads at different levels. The best-suited level of dry fruit and powder was for biscuits 15% and 2%, respectively. Biscuits were kept for evaluation (18 days) and retained texture for 10 days and off flavour was sensed on 14th day of evaluation. The best suited level of dry fruit and powder for bread was 15% and 4%, respectively. Bread was kept under observation for 6 days and was evaluated at 2 days-intervals. Due to moisture loss, hardening occurred on 4th and dryness on the 6th day (Nayak, Jamuna and Chandru, 2013) [18] .

Appetiser

Different juice and TSS combinations were tried for preparing mulberry appetizer (spiced squash)and the one with 40% juice and 40°B TSS was best suited combination with highest sensory attributes (Hamid and Thakur, 2017) [25] Squash -Combination of 30% juice and 45 ° B was rated best based on sensory, physiochemical and quality attributes (Thakur and Hamid, 2017) [25] .

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