Livestock Research for Rural Development 34 (10) 2022 LRRD Search LRRD Misssion Guide for preparation of papers LRRD Newsletter

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Fermentation characteristics and chemical composition of fermented rice bran with different levels of palmyra sap (Borassus flabellifer)

Theresia Nur Indah Koni, Tri Anggarini Yuniwati Foenay and Antonius Jehemat1

Department of Animal Science, Politeknik Pertanian Negeri Kupang
1 Department of Dryland Agriculture Management, Politeknik Pertanian Negeri Kupang
Jl. Prof. Dr. Herman Yohanes Lasiana Kupang P O Box. 1152, Kupang 85011, Indonesia


An experiment was carried out to determine the effects of palmyra sap on fermentation characteristics and chemical composition of fermented rice bran. The palmyra sap was mixed with rice bran ensiled in a plastic container and incubated for six days. The experiment was assigned in a completely randomized design with four treatments with three replications. The results showed that palmyra sap improved fermentation quality by reducing final pH, NH3, and increasing lactic acid. Fermentation reduced dry matter, crude fiber, crude fat, phosphorus, NDF, and ADF, but increased of crude protein contents of rice bran. It can be concluded that 10% palmyra sap could be utilized to improve fermentation characteristics and nutritive value of ensiled rice bran.

Keywords: fermentation quality, nutritive value, palmyra sap, rice bran


Rice bran (RB) is the main by-product of rice processing, which is widely used in rice-producing countries as an animal feed (Marbun et al 2018). Rice processing consists of 65% rice, 10% rice bran, and paddy husk 23% (Superianto et al 2018). Rice production in East Nusa Tenggara Province, Indonesia in 2021 was 731878 tons (Statistic 2021). Based on rice production, the average rice bran production is 73187.8 tons.

The nutritional content of RB was 88.9% dry matter, 74.1% organic matter, 2.8% crude fat and 26.4% crude fiber (Mila and Sudarma 2021). Novita et al (2017) reported that the crude protein, calcium, phosporus, magnesium and metabilizable energy of RB were 12.9%, 0.07%, 0.22% and 2980 kcal/kg, respectively. RB is commonly used as animal feed (Shuvo et al 2022). In poultry feed it can be used up to 10% (Munandar et al 2020).

However, RB also contains high fiber and phytic acid, which could impair animal growth. Ermalia et al (2016) reported that the crude fiber (CF), neutral detergent fiber (NDF), and acid detergent fiber (ADF) of RB were 28.27%, 45.24%, and 36.45%, respectively. The phytic acid content of rice bran was 0.91g/100g DM (Azrinnahar et al 2021).

The fermentation process using microbes can increase the nutrient value and quality of the feed ingredients. It can be reduced crude fiber (Munira et al 2016, Ali et al 2018), and the reduction of phytic acid levels of rice bran (Azrinnahar et al 2021, Rahayu et al 2018). Fermentation requires a carbon source as energy for microorganisms, one of the carbon sources is palmyra sap.

Palmyra sap (PS) is the main result of tapping from the palmyra tree ( Borassus flabellifer). Morton (1988) reported that the palmyra sap (toddy) obtained by binding, beating, and then slicing the tip of the inflorescence for 8 successive days. PS contains 10-20% sugar (Francisco Ortega and Zona 2013), most of the sugar is in the form of sucrose, which is 76.86% (Vengadaramana et al 2016), and 1.66% glucose (Morton 1988). Meanwhile, Naiola (2008) has reported PS from East Nusa Tenggara contains of glucose by 3.5% and disaccharide sugars namely fructose and sucrose, respectively by 4.05% and 3.6%.

PS is not only a source of sugar or carbohydrates but also contains microorganisms that are useful in the fermentation process. Vengadaramana et al (2016) reported that several microorganisms have been isolated from the sap such as Saccharomyces cerevisiae, S. chevalieri, Kloeckere apiculata, Schizosaccharomyces pombe, and bacteria (Bacillus cereus, B. sphericus, B. firmus). Meanwhile, Wellala et al (2006) reported that the dominant micro-organism in palm sap is Saccharomyces cerevisiae, which converts sugar into alcohol. In addition, lactic acid bacteria such as Leuconoctoc mesenteroides, Leuconoctoc pseudomesenteroides, Lactobacillus plantarum, and Lactobacillus fermentum have been isolated from palmyra sap from East Nusa Tenggara, this was reported by Chayaningsih (2006).

The presence of Saccharomyces cerevisiae in PS will accelerate the reduction of oxygen in the fermentation process so that anaerobic conditions were achieved more quickly followed by a decrease in pH, thereby minimizing protein degradation in the fermented material. PS has been used in the fermentation of banana peels. Koni et al (2021) reported that the crude fiber content of banana peel fermented for six days using 20% PS, and without PS were 11.55%, and 18.71%, respectively.

Therefore, the purpose of this study was to determine the effect of PS levels on fermentation characteristics and nutrient content of RB.

Material and methods

Experimental design

This study used a completely randomized design with 4 treatments and 3 replications. RB was fermented anaerobically for 6 days with different levels of PS (0, 10, 20, and 30% based on dry matter). Urea was added (2% of fresh weight) in all treatments.

Fermentation process

RB was obtained from a rice mill in Kupang. PS was obtained from palm tappers in Kupang. The RB samples were analyzed for dry matter content using the oven drying method at a temperature of 105°C according to AOAC (2005). The RB is cleaned of impurities, weighed, mixed with palm sap according to the treatment and with 2% urea (20 g/kg mixture based on fresh weight). The levels of PS were 0, 10, 20, and 30% (based on dry matter). After mixing, the material is closed in a plastic container, compacted to remove air, and tightly closed on the surface of the plastic container is sealed to achieve anaerobic conditions. The mixture was then incubated at room temperature (23 to 30°C) for 6 days. At the end of the fermentation, the plastic containers were opened for the determination of pH, lactic acid, ammonia, proximate analysis, fiber fraction, and minerals.

Determination of the pH of each sample using fermented RB, as much as 2 g of fermented RB was added to 10 ml of distilled water, then stirred, the pH was determined using a pH meter electrode according to Bernardes et al (2019). Fermented RB was analyzed for its lactic acid content according to Barker and Summerson (1941) and NH3 according to Chaney and Marbach (1962). The dry matter contents, crude protein, ether extract, ash were determined according to AOAC (2005). Fibre fractions analysis were done according to the procedure of Van Soest et al (1991). Calcium was determined by the AAS method and phosphorus using spectrophotometry (AOAC 2005).

Statistical analysis

Data collected were subjected to a one-way analysis of variance procedure using SPSS version 20 software. The differences among the means were determined using the Duncan multiple range test of the same software.

Results and discussion

Characteristics of fermented rice bran

Characteristics of rice bran fermentation such as pH, NH3 and lactic acid produced after the fermentation process. Fermented RB used PS had lower pH (p<0.01) compare to those without PS (Table 1). The low pH values found in using PS in fermented RB may be attributed the soluble carbohydrates in PS. Naiola (2008) stated that PS consists of 3.5% glucose, 3.6% fructose, and 4.05% sucrose. After 6 six days fermented sugar in palmyra sap has converted to lactic acid by metabolized of microorganism. The decrease in pH may be due to the sugar content in PS, which provides nutrients for the growth of microorganisms in anaerobic fermentation. If microorganism have obtained nutrient they will in optimum growth condition so that could produce high organic acids, and it will be have implications for decreasing pH. The content of water-soluble carbohydrates in the fermented material is directly proportional to the rate of decrease in pH. This is consistent with a previous study showing that using water soluble carbohydrates such as molasses, rice bran, cassava flour, and corn flour in silage process can have low pH (Rusdy 2015). In anaerobic fermentation products, lactic acid levels are inversely proportional to pH (Utomo et al 2013).

Table 1. The effect level of palmyra sap (% on dry matter basis) on the pH, NH3 and lactid acid of RB after 6 days of fermented


Palmyra sap (% dry matter)














NH3 (mg/100g)







Lactit acid (mg/100g)







a,b,c,d means in the same row without a common letter are different at p<0.05, SEM: Standard error of the mean, p: probability

Increasing PS caused decreasing in NH3 produced by fermented RB (Table 1). The amount of NH3 describes how much protein has been degraded by unwanted microbial activity (Despal et al 2011). The levels of NH3 in fermented RB with PS were lower than in treatment without PS. This is because the sugar contained in PS will be converted into lactic acid, thereby lowering the pH. Fructose and glucose in silage will be converted into lactic acid (Wilkinson et al 2003). There is an inverse relationship between the decrease in pH and the production of NH3. Proteolytic microorganisms live in alkaline conditions. Santoso et al (2009) reported that the breakdown of proteins into amino acids and then amino acids into ammonia is generally due to the action of proteolytic Clostridia that live at pH 6-8.5. In the low pH condition, protein-degrading cannot happen.

The level of PS caused an increase (p <0.01) in lactic acid levels (Table 1 and Figure 1). There is a positive relationship between PS and lactic acid production on fermented RB. The use of PS up to 20% DM causes an increase in lactic acid levels, then decreases at 30% DM. This increase in lactic acid levels is because in PS there is yeast Saccharomyces cerevisiae which is aerobic so that oxygen levels at the beginning of the fermentation process are consumed and cause anaerobic conditions to be achieved faster, and lactic acid bacteria can produce lactic acid and lower pH.

The presence of Saccharomyces cerevisiae will also have a positive impact on the reduction of CH4 produced in ruminants, which consume this fermented rice bran. The 10% PS treatment had the highest lactic acid content (p <0.05). Lactic acid will be utilized by bacteria in the rumen to produce propionate. This can reduce methanogenesis because electrons are used for propionate formation. If hydrogen is then used to convert lactic acid to propionic acid in the rumen the hydrogen will decrease, which in turn will inhibit the conversion of hydrogen and CO 2 to methane (Khota et al 2017).

Yeast (Saccharomycetes cerevisiae) also has the potential to alter the fermentation process in the rumen in a manner that reduces the formation of methane (CH4) gas. Chung et al (2011) reported a shift in H2 utilization from methanogenesis to reductive acetogenesis by yeast. Oskoueian et al (2021) reported that an in vitro rumen digestibility test showed higher rumen digestibility, higher VFA production and lower methane production in the rice straw fermented compared with control. Therefore, we suspect that fermented RB by PS with high lactic acid content may have led to higher propionic acid production and reduced methane production accordingly. Bacteria produce lactate, which is eventually converted to propionate by lactate-utilizing bacteria such as Megasphaera elsdenii, which can produce propionate using the acrylate pathway (Takahashi et al 2005).

Cao et al (2010) reported that sheep that were fed fermented complete feed increased 11.70% digestibility, 5.94% propionate production, and 25.10% reduce CH4 emission compared to sheep fed the control diet. Thus the provision of fermented feed can be more environmentally friendly. The present study, high levels of lactic acid at the level of 10% sap may be due to the balance between nutrients and fermentation time so that microorganisms are in the logarithmic phase and produce the highest lactic acid. At levels of 20 and 30%, PS lactic acid produced decreased this was probably because the high amount of substrate caused high growth so the rate of nutrient depletion in the substrate was even earlier, maybe the level of >10% fermentation time should be shortened. Growth of microorganisms is highly dependent on substrate nutrients (Stanbury et al 2003).

Figure 1 . Relationship between lactic acid and PS on fermented RB
Nutrition of fermented rice bran

The results of the effects of palmyra sap treatments on the nutrient content of RB were shown in Table 2 The dry matter content in the treatment using PS was lower (p <0.05) than the control treatment. This is due to the high water content of palmyra sap, and its liquid form. A decrease in the dry matter content also occurred in rice bran fermented with Aspergillus niger as reported by Ahmad et al (2019). Increasing crude protein of fermented RB is caused by the contribution of crude protein from palm sap. The crude protein content of PS is 0.52% (Naiola 2008). The present study in line with Koni et al (2021) hows that the use of the PS can increase the crude protein of fermented banana peels. However, it inconsistent with Sandi (2012) reported that the use of 15% PS in fermented cassava peels did not cause an increase in crude protein content.

Table 2. Effect of palmyra sap level (% dry matter basic) on proximate composition, fiber fraction, and mineral content of fermented RB


Palmyra sap (%)







Proximate composition

Dry matter (%)







Ask (% DM)







Crude protein (% DM)







Crude fiber(% DM)







Ether extract (% DM)







Fibre Fraction

NDF (%)







ADF (%)







Hemicellulose (%)







Cellulose (%)







Lignin (%)








Ca (%)







Phosphorus (%)







a,b,c means in the same row without a common letter are different at p<0.05, SEM: Standard error of the mean, p: probability

RB fermentation by PS were decreassing in crude fiber and phosphorus content. This result was in line with Wolayan and Mandey (2019) that the nutrient content of RB improved after fermentation by Saccharomyses cerevisiae. Fermented can reduce neutral detergent fiber, acid detergent fiber in rice bran. Neutral detergent fiber, acid detergent fiber in fermented rice bran using palm sap is lower than in fermented rice bran without palm sap. This can be caused by the soluble carbohydrates contained in palm sap which causes the high number of lactic acid bacteria to produce more cellulolytic enzymes.



The author would like to thank the Kupang State Agricultural Polytechnic for supporting the financial of this activity through the PNBP Applied Research in Fiscal Year 2022.


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