The effect of the use of rice bran in the fermentation of chayote (Sechium edule) on the nutrient, content minerals and digestibility of the dry matter and organic matter of chayote fruit

Redempta Wea, Yola Yunita Amseke¹, Yupipin Frilani Keo¹, Yutri Misa¹, Wempi Takesan¹, Bachtaruddin Badewi, Helda¹, Bernadete Barek Koten¹, Melkianus Dedi Same Randu and I Gusti Komang Oka Wirawan¹

Animal Production Study Program, Department of Animal Husbandry, Kupang State Agricultural Polytechnic, Indonesia
redemptawea136@gmail.com
¹ Animal Feed Technology, Department of Animal Husbandry, Kupang State Agricultural Polytechnic, Indonesia
² Animal Health Study Program, Department of Animal Husbandry, Kupang State Agricultural Polytechnic, Indonesia

Abstract

Pig fodder competes with human needs, one of which is chayote, which is abundantly available during the harvest season and even becomes waste. Therefore, in order to maintain the nutritional content and increase the shelf life so that it can be used when there is a shortage of feed, fermentation is carried out using dissolved carbohydrates, namely rice bran. The aim of the research was to examine the nutrient, mineral, and digestibility of dry matter and the organic matter digestibility of chayote due to the addition of rice bran levels in the fermentation process. Research using a completely randomized design (CRD) with 4 treatments and 5 replications consisting of rb0: chayote without rice bran, rb5: chayote + 5% rice bran, rb10: chayote + 10% rice bran, and rb15: chayote + 15% rice bran. Parameters observed were the content of nutrients, minerals, and digestibility of dry matter and organic matter. The analysis used one-way analysis of variance and The Duncan multiple range test (DMRT). The results showed that increasing the addition of rice bran up to 15% caused a decrease in water content, organic matter (BO), non-nitrogen extract material (NNEM), Ca, K, digestibility of dry matter and organic matter, and the use of the best rice bran in chayote fruit fermentation is 5%. It was concluded that the use of rice bran levels in chayote fruit fermentation affected the nutrient, mineral, and digestibility of dry matter and organic matter, and the best level was 5%.

Keywords: bioconversion, soluble carbohydrates, pigs, nutrition

Introduction

Feed is a very important factor 60–80% of production costs) in increasing livestock production and productivity. Animals that are in a period of growth require sufficient nutritional needs to support perfect growth.

The availability of feed in the Province of East Nusa Tenggara (ENT) greatly increases during the rainy season, but during the dry season, the availability of feed is very insufficient to meet the needs of livestock. One of the efforts to overcome the shortage of feed during the dry season is the preservation of forage during the rainy season, which has not been widely used or utilized. One of them is the chayote.

The availability of chayote is abundant in the areas of ​​South Middle East District (TTS), South Amanatun District, and Fatulunu Village. Siamese pumpkin, or what we know as jipang, is sold and consumed by the people themselves as a vegetable ingredient. The production of chayote in NTT in 2020 reached 16,714 tons (BPS 2020). However, until now, the chayote fruit was generally only used as a vegetable by most people, so most of the chayote fruit that is thrown away is useless because it rots. Siamese pumpkin fruit can be used as animal feed. However, the weakness is that the chayote cannot be stored for a long time. This is because the chayote has a very high-water content, which makes it easy to rot. Siamese pumpkin has a water content of 83% (USDA 2013). The Siamese pumpkin (Sechium edule) is one of the plants of the gourd tribe (Cucurbitaceae). Chayote, aside from being used as a vegetable, also has great potential as a traditional medicinal ingredient (Rosidah et al 2017). The nutritional content of chayote in this study was 4.83% dry matter, 10.16% crude protein, 1.31% crude fat, 22.05% crude fiber, 50.56% non-nitrogen extract material and 8.12% ash. Therefore, it is necessary to process chayote as animal feed during the abundance season so that it can be utilized during famine or feed shortages. One method of processing chayote into animal feed is fermentation.

Fermentation is a process of chemical changes in an organic substrate through the activity of enzymes produced by microorganisms (Suprihatin 2010). The activity of fermenting microorganisms can take place maximally, it requires a source of soluble carbohydrates that are easily digested. One source of soluble carbohydrates is rice bran.

Rice bran is a byproduct of the process of breaking the grain husk, which consists of the top layer of outer skin in the rice milling process, and is one of the most preferred ingredients for animal feed. Milled rice bran contains 89.836% dry matter, 9.831% crude protein, and 14.717% crude fiber (Mila dan Darmawan 2021). The bran level affects the amount of nutrients available for microbial activity, which affects the nutrient levels of fermented pumpkin, so this research was conducted.

Materials and methods

Research location

The research was carried out at the Animal Feed Nutrition Laboratory and the animal feed factory of the Kupang State Agricultural Polytechnic in October 2021–January 2022.

Research procedure

Preparation of tools and materials: the research was preceded by the preparation of tools and materials in the form of chayote from South Middle East District, South Amanatun District, Fatulunu Village, rice bran as a source of soluble carbohydrates, scales, and other supporting tools.

Implementation of chayote fruit fermentation: Chayote fruit that is ready is then chopped ± 2 cm, weighed fresh, dried in the sun until the moisture content reaches 60% (%KA = final weight/initial weight x 100%), weighed, mixed with rice bran according to the treatment evenly, compaction in the fermentation container, closed the container so that the anaerobic atmosphere is maintained, and fermented for 21 days.

Parameter measurement: after 21 days of unloading fermented products, weighing, separating moldy, from non-moldy, observing physical quality, weighing to obtain weight before drying, drying samples in an oven at 60°C for ±3 days, weighing to obtain weight after baking, milling and screening with a sieve diameter of 1 mm, packaging, and coding for analysis; sending samples to the laboratory at 250 g/sample for analysis of nutrient content according to research parameters.

Research parameters

The research variables were nutrient content (moisture content, dry matter/DM, organic matter/OM, crude protein/CP, crude fat/CF, crude fiber, non-nitrogen extract material/NNEM, and ash), mineral content (Ca, P, and K), and digestibility of dry matter and organic matter digestibility based on AOAC guidelines (AOAC 2012).

Experimental design

This study used a completely randomized design (CRD) consisting of 4 treatments and 5 replications, for a total of 20 experimental units. The treatment was as follows: rb0: chayote without rice bran (control); rb5: chayote + 5% rice bran; rb10: chayote + 10% rice bran; rb15: chayote + 15% rice bran.

Data analysis

Research data were analyzed using analysis of variance (ANOVA) and further tested using Duncan's Multiple Range Test (Gomez, Gomez 2010).

Results

Nutrient content

The effect of treatment on the water content of chayote fruit can be seen in Table 1. Analysis of variance showed that the level of use of rice bran had a very significant effect (p<0.01) on the water content of fermented chayote fruit. Duncan's test showed that the water content of fermented chayote was highest in treatment rb0 (93.99%). The decrease in water content was shown in treatments rb5, rb10 and rb15, and the lowest was in rb15 (86.92%). The difference in total water content between rb0 and rb5 was 4.37%, rb0 and rb10 was 6.8%, and rb0 and rb15 was 7.07%.

The effect of treatment on the dry matter content of chayote pumpkin fruit can be seen in Table 1. Analysis of variance showed that the addition of different levels of rice bran had a very significant effect (p<0.01) on the content of chayote fermented DM. Duncan's follow-up test showed that the GC content of fermented chayote was highest in treatment rb15 (13.08%), which was different (p<0.05) from treatments rb10, rb5, and rb0, and the lowest was in rb0 (4.83% ). It can be seen that the higher the addition of rice bran, the higher the content of chayote fruit.

Data on the effect of each treatment of chayote fermented with the addition of different levels of rice bran on the organic matter content is shown in Table 1. The results of the analysis of variance showed that the addition of different levels of rice bran had a very significant effect (p<0.01) on the content of chayote fermented organic matter. After each rice bran treatment, the organic matter content contained in the chayote fruit fermentation decreased. Duncan's Multiple Range Test showed that the lowest organic matter content was found in treatment rb15, followed by treatments rb10, rb5, and rb0. Where the comparison between rb0 and rb5 decreased by 3.55%, followed by treatments rb0 and rb10, which also decreased by 5.03% and in the treatment rb0 and rb15 also decreased by 6.73%.

An analysis of variance showed that the addition of rice bran level had a very significant effect (p<0.01) on the CP content of fermented chayote. Duncan's further test for changes in the CP content of fermented chayote fruit, as shown in Table 1, shows that the CP content of fermentation increases with the addition of rice bran up to 15%. The difference in CP levels between the control treatment (rb0) and the treatment with the addition of 5% rice bran (rb5) increased by 1.71%, the control treatment (rb0) with the addition of 10% rice bran (rb10) increased by 2.95%, and the control treatment (rb0) with the addition of 15% rice bran (rb15) increased by 7.8%.

Data on the effect of treatment on the crude fat content of chayote fruit fermentation can be seen in Table 1. Analysis of variance showed that different levels of rice bran had a very significant effect (p<0.01) on the crude fat content of chayote fermentation. The crude fat content of fermented chayote in this study increased with the increasing amount of rice bran added. Duncan's test showed that the highest CF level was found in treatment rb10 which was not different from rb0 (p<0.05). The lowest crude fat content was in rb0, with rb5 increasing by 1%, rb0 with rb10 increasing by 1.21%, and rb0 with rb15 increasing by 1.17%.

Data on the effect of treatment on crude fiber content of chayote can be seen in Table 1. The results of the analysis of variance showed that the addition of rice bran to the fermentation of chayote had a very significant effect (p<0.01) on crude fiber content. Duncan's test showed that the highest fiber content was found in treatment rb15 (34.69%) and the lowest in treatment rb0 (22.05%).

Data on NNEM levels in fermented chayote with the addition of different levels of rice bran are shown in Table 1. Analysis of variance showed that chayote and rice bran had a very significant effect (p<0.01) on the NNEM content. Duncan's Multiple Range Test showed that the lowest NNEM content was found in treatment rb15, followed by treatments rb10, rb5, and rb0. Where the comparison between rb0 and rb5 decreased by 5.72%, followed by treatments rb0 and rb10, which also decreased by 8.04%, and in the treatment rb0 and rb15, which also decreased by 12.78%.

Data on the effect of treatment on the ash content of fermented chayote can be seen in Table 1. Analysis of variance showed that the ash content of fermented chayote was strongly influenced (p<0.01) by the addition of rice bran levels. In Table 3, It can be seen that the ash content of fermented chayote increases with the addition of rice bran. Duncan's further test showed that rb15 had the highest ash content, which was significantly different (p<0.05) from the treatments rb10, rb5, and rb0. The difference in the ash content of the treatments rb0 and rb5 was 3.57%, rb0 with rb10 was 5.03% and rb0 with rb15 was 6.73%. It can be seen that the addition of 15% rice bran increased the ash content by 6.73%.

Mineral content

Data on the effect of rice bran level treatment on fermented chayote pumpkin calcium levels can be seen in Table 2. Analysis of variance showed that the use of rice bran level had a very significant effect (p<0.01) on fermented chayote Ca levels. Duncan's test showed that the highest Ca content was found in chayote without rice bran (rb0), which was 0.148%, which was different from rb5, rb10, and rb15. The lowest Ca content was found in the addition of 15% rice bran which was 0.059%.

Data on the effect of rice bran level treatment on fermented chayote fruit levels of potassium (K). Analysis of variance showed that the addition of different levels of rice bran had a very significant effect (p<0.01) on the fermented potassium content of chayote. Duncan's test showed that the highest levels of potassium (K) were found in the rb0 treatment without rice bran, which was called the control, which was 2.126%, which was different from the rb5, rb10, and rb15 treatments. The lowest potassium level in this study was 0.744%, found in the addition of 15% rice bran.

Data on the effect of rice bran level treatment on phosphorus (P) levels of fermented chayote. Analysis of variance showed that the addition of different levels of rice bran had a very significant effect (p<0.01) on the phosphorus content of chayote fruit fermentation.

Duncan's test showed that the highest fermented chayote fermented phosphorus was found in the treatment with the addition of 15% rice bran level (rb15), namely 0.823%, which was different from the treatments rb0, rb5, and rb10. The lowest phosphorus content was found in the rb0 treatment without rice bran, with a value of 0.518%. The average level of phosphorus in fermented chayote seems to increase with increasing levels of rice bran, up to 15%.

Digestibility of dry matter and organic matter

Data on the effect of treatment on dry matter digestibility can be seen in Table 3. The results of the analysis of variance showed that the digestibility of chayote fermented dry matter was affected by rice bran at different levels. Duncan's test showed that the highest dry matter digestibility was at rb0 (70.01%). The difference (p<0.05) with rb5, rb10, and rb15 and the lowest dry matter digestibility value were found in rb15. When compared with rb0 (70.01%). It can be seen that the higher the addition of rice bran, the lower the digestibility of chayote dry matter.

The average digestibility value of chayote fermented dry matter with various levels of rice bran in Table 3 shows that the rb0 treatment (70.01%) without the addition of rice bran had the highest value compared to the other treatments, and the DMD value ranged from 70.01% to 61.33%.

Data on the effect of treatment on the digestibility of chayote organic matter is shown in Table 4. The results of the analysis of variance showed that the addition of different levels of rice bran had a very significant (p<0.01) effect on the digestibility of chayote-fermented organic matter. Duncan's test showed that the highest treatment of chayote fruit fermentation was in treatment rb0 (control), which was significantly different (p<0.05) from rb5, rb10, and rb15. The average digestibility of organic matter ranged from 56.65% to 68.11%.

Discussion

The decrease in water content with the addition of rice bran and the highest in chayote without rice bran were due to the absence of additives in the treatment. The average water content in fermented chayote in this study was 89.43%. The high content of dry matter (DM) in the fermentation of chayote fruit, along with the increase in the addition of rice bran, was due to the addition of DM from rice bran. The low DM content in chayote without rice bran (rb0) is due to the absence of additional rice bran as a source of dry matter in this fermentation. This is in line with the opinion of Barokah et al (2017) that the high or low content of fermented DM is determined by the materials used and the activity of microorganisms during the ensilage process. The DM content is lower than the study reported by Santi et al (2011) in banana stem silage with the addition of several accelerators such as rice bran and cassava flour, which is 22.80%. This is due to the different types of raw materials and the nutrient content of the raw materials used.

The low organic matter (OM) content up to rb15 is due to the degradation of organic matter during the ensilage process. Reduced organic matter, especially cell contents, during the fermentation process because it is utilized by microorganisms. This condition the organic content of fermented chayote fruit. In the ensilage process, several activities occur, including: respiration, where carbohydrates are broken down into CO₂, H₂O, and energy; proteolysis, where proteins are broken down into ammonia, amino acids, acetic acid, butyric acid, and water, and carbohydrate breakdown where carbohydrates are broken down into alcohol, lactic acid, butyric acid, carbonic acid and heat release. These three processes will reduce the silage’s organic matter.

Fermented crude protein (CP) levels increased with the addition of rice bran by up to 15% because, during the ensilage process, a fermentation process involving microbes occurred. The microbes then develop in the fermentation, which will increase the fermented CP levels. When rice bran is added to 15%, microbial development experiences an increase in growth as evidenced by the increased contribution of microbial protein to the fermentation. This is in line with the opinion of Kusumaningrum et al (2012) that the increase in protein content of fermented feed ingredients is due to microbial activity and the addition of protein contained in the microbial cells themselves. The increase in CP indicates that the addition of rice bran to the fermentation of chayote has a good effect on the crude protein content of fermented chayote. The CP content of this study (13.27%) was higher than the study reported by Dhalika et al (2011) on silage of banana stems mixed with cassava and corn kernels, where the CP of the silage obtained was 12.17%.

The crude fat (CF) content of fermented chayote has increased in line with the increase in rice bran due to the additional crude fat content of rice bran, where rice bran has a relatively high crude fat content of 15%. This is in accordance with the opinion of Amrullah et al (2015), which states that the increase in crude fat content in fermentation depends on the amount of additives added and the fat content of these additives, while the low crude fat content in the rb0 treatment is thought to be caused by the absence of additional fat from rice bran, also the presence of fat degradation by microbes that work during the fermentation process. The decreased crude fat content is also caused by triglyceride bonds, which are broken down into simpler bonds, among others, in the form of crude fatty acids and alcohols.

The increase in the use of rice bran in the chayote fermentation process causes an increase in crude fiber and is thought to be caused by the high level of addition of rice bran because rice bran has a crude fiber value of 30.73%. This has implications for increasing levels of crude fiber in chayote fruit fermentation. According to Felly and Kardaya (2017), the increase in crude fiber was due to the increased content of NDF and ADF, which are components of crude fiber.

The low content of NNEM in treatments rb5, rb10, and rb15 is caused by the process of degradation of the material (substrate) by microbes during the fermentation process. Risma (2015) stated that in the fermentation process, the NNEM content tends to decrease because the NNEM is used as energy by the microbes in their growth. The use of easily digestible carbohydrate energy sources in microbial activity as an initial stage for growth and reproduction. An increase in microbial activity in degrading substrates will also affect more and more energy use, so that high microbial activity can reduce the NNEM content.

The higher the use of rice bran, the high ash content, which is suspected because during the fermentation process there is degradation of the organic matter of chayote fermented by microbes during the ensilage process. This is in line with the opinion of Koten (2010), who stated that reduced organic matter, especially cell content, during the fermentation process resulted in an increase in ash content.

The decrease in calcium levels with the addition of rice bran was due to the higher the level of rice bran, the fact that the higher the growth of microorganisms, and the higher the need for minerals for the growth of these microorganisms so the less minerals present in the squash substrate. This was caused by the acidic atmosphere that occurred during the study, namely with a pH of 4. According to Kismiati et al (2012), the mineral calcium is a mineral that dissolves in acids. Besides that, fermentation microorganisms will utilize substrate nutrients, including minerals, for their life activities and produce enzymes that will digest complex nutrients into simpler ones so that they are more available and easier to use. This will reduce the level of calcium (Ca) silage. The Ca content of fermented chayote in this study was 0.088%, which was lower than the calcium content of fermented banana peels using tapioca, which was 0.16% in Koni's (2013). This is understandable because of the differences in the raw materials used.

The average potassium level of fermented chayote in this study was 1.344% higher than the potassium level of tamarind seeds ripened with palm sap, which was 0.52% higher than the results of Wea's study (2016) due to differences in the raw materials used. Potassium levels decrease because, during the ensilage process, microorganisms utilize potassium minerals from existing materials for their growth. The acidic atmosphere created during the ensilage process causes potassium to dissolve easily. This soluble potassium will be used by active microbes in the ensilage process. This condition lowers potassium levels.

Phosphorus levels increased as rice bran increased in chayote fruit fermentation because the phosphorus content of the soluble carbohydrates used contributed to the phosphorus levels of the resulting silage. In addition, the fermentation process can degrade phytate, which binds phosphorus in feed ingredients such as rice bran. The results of this study are in accordance with the opinion of Saihaan et al (2015) that there was an increase in phosphorus due to a decrease in phytic acid in sesame beans, namely before fermentation at 31.59 (mg/g) after fermentation at 18.13 (mg/g). In addition, fermented rice bran under anaerobic conditions with a pH range of 4.5 will support the activity of the phytase enzyme so that the decomposition process occurs and will reduce the phytic acid content in the rice bran. The phosphorus content in rice bran in the form of phytic acid is 89.9%. After the decomposition process occurs, the phosphorus minerals contained in phytic acid will be released and act as a source of organic phosphorus (Irianingrum 2009). The pH in this study was 4 (acidic), so the addition of rice bran to chayote reduced the phytic acid content and increased the phosphorus content in rb15 with the addition of 15% rice bran, namely 0.823%. Thus, the statement of Ravindra et al (2000) that during the fermentation process microorganisms will produce phytase enzymes, which is one way to overcome the high content of phytic acid in feed, because phytase enzymes have the ability to hydrolyze phytic acid contained in feed ingredients into inositol and glucose compounds and organic phosphorus compounds.

The higher the addition of rice bran levels in the chayote fruit fermentation, the lower the DM digestibility of chayote silage. This is thought to be due to the crude fiber content, which is part of the dry matter and increases with the use of rice bran in the fermentation process. High crude fiber content reduces digestibility because the cell walls are more resistant to fiber-digesting microorganisms, which can lead to lower digestibility of feed ingredients. On the other hand, feed ingredients with low SC are generally easier to digest because the cell walls of the material are thin, making it easy for microbes to penetrate.

The digestibility of organic matter decreased in line with the addition of rice bran because, during the ensilage process, the chayote was used by microbes as an energy source that supports microbial activity, so the organic matter content decreased when the level of rice bran increased. The decrease in OM digestibility in the chayote fruit fermentation process is due to the overhaul of organic matter, especially carbohydrates that dissolve easily in silage, which is used as an energy source for the growth and activity of microorganisms (Wajizah et al 2015). The decrease in the digestibility of dry matter and organic matter is due to the nutrient content of rice bran, which is a soluble carbohydrate and a living medium for microorganisms to produce a good fermentation process.

Conclusion

• The use of rice bran levels in chayote fruit fermentation affects the nutrient content, minerals, and digestibility of dry matter and organic matter, and the best level is 5%.

Acknowledgements

We would like to thank the leadership of the Kupang State Agricultural Polytechnic for trusting us to use the laboratory and all the teams involved in carrying out this research.

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