Quality of Vegetable Waste Silages Treated with Various
Carbohydrate Sources
Wulansih Dwi Astuti*, Yantyati Widyastuti, Roni Ridwan, & Elvi Yetti
Research Center for Biotechnology, Indonesian Institutes of Sciences (LIPI) Jalan Raya Bogor Km 46, Cibinong 16911, Indonesia
*E-mail: wulan_nie@yahoo.com
Abstract
The aim of this research was to evaluate the quality of vegetable waste silages, using rice bran, onggok (cassava flour waste) and pollard as carbohydrate sources. Vegetable waste was collected from local traditional market, consisted of corn husk, chinese cabbage dan cabbage. Research was held in Randomized Block Design consisted of six treatments with 3 replications. Treatments were (T1) vegetable waste+rice bran, (T2) vegetable waste+rice bran+rice straw, (T3) vegetable waste+onggok, (T4) vegetable waste+onggok+rice straw, (T5) vegetable waste+pollard, (T6) vegetable waste+pollard+rice straw. Lactobacillus plantarum 1A-2 was used as innoculant. The quality of silages was evaluated by measuring pH, temperature, population of lactic acid bacteria and lactic acid production. Nutrient characteristic was determined by proximate and fiber analysis. Results showed that pH of silages were not affected by treatments, but silage treated with rice bran, with or without rice straw addition, had higher temperature compared with others (29oC or 28,3oC). The highest population of lactic acid bacteria (1.9 x 107cfu/ml) was found in silage using rice straw and onggok (T4), but highest lactic acid production (0,91) was measured in silage using rice straw and rice bran (T2). In general, the use of rice bran as carbohydrate sources gave highest lactic acid production followed by pollard and onggok. Different carbohydrate source gave different nutrients characteristic. Silage with highest protein content was measured in silage with pollard as carbohydrate source, followed with rice bran and onggok.
Keywords: Lactobacillus plantarum 1A-2, onggok, pollard rice bran, vegetable waste silages
Introducton
for rumnant, to overcome lack of grass, especally n dry season. Vegetable waste s part of the vegetables that are not consumed by humans, usually already dscarded by traders, so has no economc value. Tradtonal farmers already gve vegetable waste to ther cattle, but ts hgh water content made t easly decayed and cannot be stored for long perod. Ths lmtaton ncreased the cost and dffcultes n handlng because farmers have to take vegetable waste from tradtonal market everyday. Treatment s necessary to mprove the qualty and the nutrtonal value of vegetable waste as feed.
Slage producton s a method of most forage preservaton whch s wdely used all over the world (Saele, 2002). It s based on natural fermentaton when lactc acd bactera (LAB) ferment water soluble carbohydrates to organc acds, manly lactc acd, under anaerobc condtons. As a result, the pH decreases, nhbtng det-rmental anaerobes, and so the most forage s preserved (Merry and Daves, 1999). A combnaton of anaerobc condton and acdty protects the forage from the pro-lferaton of deleterous bactera and fung, and t also ncreases the palatablty of the forage due to lactc acd producton (Yang et al., 2001, Wenberg et al., 2003, Flya, 2003).
In terms of storage, slage s more durable because of spolage bactera do not resstant to low pH, so ts avalablty and qualty of feed can be assured. Slage can also be used as probotcs and organc acd sources for lvestocks as an alternatve to antbotcs. In order to mprove the enslng process and to obtan a hgh-qualty fermented product, varous chemcal and bologcal addtves have been developed and used durng slage fermentaton. The bologcal addtves are advantageous be-cause they are safe and easy to use, non-corrosve to machnery, do not pollute the envronment and are regarded as natural products (Flya et al., 2000; Wenberg and Muck, 1996). Seale et al. (1986) found that sugar s a lmtng factor n producng good-qualty fermented products. Sugar manly serves as a carbon source for mcro-organsms. Molasses, lactose and a mxture of cereal grans and malt, dextrose, corn or tapoca flour have been used as addtves (Zahar et al., 2002).
A successful enslng process requres a mnmum concentraton of fermentable sugars (3-5% n DM). However, the majorty of carbohydrates n plants are n the form of fbrous polymers that make up the cell wall and are not fermented by lactc acd bactera (LAB). In order to obtan the necessary level of fermentable water-soluble carbohydrates (WSC) for the lactc fermentaton n crops whch are low n WSC, the use of carbohydrate sources has been suggested.
Materals and Methods
Vegetable waste was collected from local tradtonal market n Bogor, con-ssted of corn husk, chnese cabbage and cabbage. After choppng, vegetable waste was ar dred to decrease water content. It was sprayed wth Lactobacillus planta-rum 1A-2 as an nnoculum and dvded nto equal portons for the applcaton of treatments. All nnocula were dluted wth dstlled water, so that they were appled at the same rate (10 ml of soluton/kg of vegetable waste).
Experment was held n a randomzed block desgn conssted of sx treatments wth 3 replcatons. Treatments were (T1) vegetable waste + rce bran, (T2) veg-etable waste + rce bran + rce straw, (T3) vegveg-etable waste + onggok, (T4) vegveg-etable waste + onggok + rce straw, (T5) vegetable waste + pollard, (T6) vegetable waste + pollard + rce straw.
Each treatment was packed nto ±15 L plastc drum as slos n trplcate and sealed. Slos were stored at room temperature. After 45 days ensled, each slo were sampled for chemcal and mcrobal analyses. The DM content was determned by oven dryng for 48 h at 60 oC. After dryng, samples were ground through a 1-mm
screen mller, and stored n glass bottle at room temperature for chemcal (prox-mate and fber) analyss. The qualty of slages was evaluated by measurng pH, temperature, populaton of lactc acd bactera and lactc acd producton. Nutrent characterstc was determned by proxmate and fber analyss at Laboratory of Feed Technology, IPB.
Another porton of orgnal sample was dluted wth autoclaved dstlled water and blended n hgh-speed blender for 30 s. The dluted samples were enumerated for LAB on pour-plates usng MRS agar (DeMan, Rogosa, and Sharpe) wth TPC (Total Plate Count) method, cultvated at 30 °C for 48 hours (modfcaton from Cappucno and Sherman, 1983). Colones were counted from plates of approprate dlutons contanng a mnmum of 30 colones. pH was mmedately measured from the remander of dluted sample.
Results and Dscusson
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Fgure 1. Physcal appearance of vegetable waste slages. T1= vegetable waste + rce bran; T2= vegetable waste + rce bran + rce straw; T3= vegetable waste + onggok; T4= vegetable waste+ onggok + rce straw; T5= vegetable waste + pollard; T6= vegetable waste + pollard + rce straw.
Other varables for evaluatng slage qualty s the chemcal (temperature, pH and lactc acd producton) and mcrobologcal (LAB populaton) characterstcs of slage presented n Table 1. Temperature of slage at the end of fermentaton vared between treatments. The hghest temperature was recorded (29 oC) on slage wth
rce bran addton (T2), whch was sgnfcantly hgher compared to others.
Value of pH, lactc acd producton, and populaton LAB were not sgnfantly affected by carbohydrate sources addton. Vegetable waste slages treated wth
ong-Note: LAB= Lactc Acd Bactera; T1= vegetable waste + rce bran; T2= vegetable waste + rce bran + rce straw; T3= vegetable waste + onggok; T4= vegetable waste + onggok + rce straw; T5= vegetable waste + pollard; T6= vegetable waste + pollard + rce straw.
Treatments
T1 T2 T3 T4 T5 T6
Temperature (oC)
28.33±0.01b 29.00±0.00b 27.00±0.00a 27.33±0.57a 27.33±0.57a 27.00±0.00a
pH 3.91±0.01 3.94±0.04 3.42±0.46 3.55±0.42 3.91±0.09 3.72±0.19 Lactc acd
gok gave the lowest pH value (3.42 and 3.55), whle the hghest pH value was ob-taned from slages treated wth rce bran (3.91 and 3.94). Ths condton may relate to the acdty of onggok whch was lower than rce bran and pollard. A pH range of 3.7-4.2 was generally consdered to be benefcal for crop preservaton (Kung and Shaver, 2001), but accordng to Bates et al. (1996), pH ranged between 3 and 4 was stll consdered adequate.
Hgh qualty slage s lkely to be acheved when lactc acd s the predomnant acd produced, as t s the most effcent fermentaton acd, and reduces slage pH (McDonald et al., 2002), thus lactc acd producton was correlated wth pH value. Hgher lactc acd producton would result n lower pH value, but n ths experment, some slages wth low lactc acd producton also had low pH value. Lactc acd producton n ths study was ranged between 0.23–0.41%, wth no sgnfcant dffer-ences among treatments. Slages treated wth onggok (T3) had the lowest lactc acd producton compared to other carbohydrate sources. Accordng to Coblentz (2003), onggok have low WSC content (3%), whle rce bran and pollard have hgher WSC content (5% and 12%). Low WSC content means low nutrent sources served for LAB to produce lactc acd.
Lactobacillus plantarum 1A-2 added as noculants durng slage makng to ncrease populaton of lactc acd bactera, n order to stmulate lactc acd fermenta-ton, accelerate the decrease n pH, and thus mprove slage preservaton of homo - fermentatve lactc acd bacteral strans. These bactera produce large amounts of lactc acd n the slage n a short tme and stablze t wth mnmal losses (Flya, 2003). In general, dfferent carbohydrate sources had not nfluenced populaton of lactc acd bactera sgnfcantly. The hghest populaton of LAB was observed n slages wth onggok addton (T4) (16.5 x 109 cfu/g), whle pollard addton (T6)
produced slages wth the lowest populaton of LAB (5.48 x 10 cfu/g 8).
Note: DM= Dry Matter; CP= Crude Proten; CF= Crude Fber; EE= Ether Extract; NFE= Non Fber Extract; T1= vegetable waste + rce bran; T2= vegetable waste + rce bran + rce straw; T3= vegetable waste + onggok; T4= vegetable waste + onggok + rce straw; T5= vegetable waste + pollard; T6= vegetable waste + pollard + rce straw.
Nutrent (%)
Treatments
T1 T2 T3 T4 T5 T6
DM 86.57 88.44 88.54 90.75 91.64 87.21
Ash 26.46 15.37 2.52 7.59 5.84 9.61
CP 7.51 9.40 3.56 4.59 14.52 13.45
CF 25.79 28.15 14.26 19.76 10.99 16.41
EE 1.70 0.30 0.12 1.01 0.19 1.15
NFE 25.11 35.22 68.08 57.80 60.10 46.59
Enslng has been a preferental method n mantanng the energy content of forages, ensurng a good nutrtonal value when used as feed (Vervaeren et al., 2010). Table 2 shows nutrent characterstcs of vegetable waste slages after 45 days of enslng. Use of pollard as carbohydrate source gave the hghest CP content (14.52%) than other treatments, whle the use of onggok provded the lowest CP content of vegetable waste slages (3.56%). Ths result s correlated wth CP content of carbohydrate sources added n slage producton. Pollard has CP content around 15%, whle rce bran and onggok have only CP content around 11% and 2% (Furqa-anda, 2004). Sapenza and Bolsen (1993) stated that CP content of qood qualty slage ranged between 10.50%-15.20%. Above the optmum range wll result n poor slage qualty and cannot be stored for a long tme due to bochemcal reac-tons between amno acds and sugars causng the Mallard reacton whch produced brown slage.
The contents of CF and EE n vegetable waste treated wth rce bran were the hghest n all slages (28.15% and 1.70) as predcted, because rce bran had the hghest CF and EE content compared wth other carbohydrate sources used n ths experment. Slage wth EE content more than 2% wll be easly contamnated and classfed as bad qualty of slage (Sapenza and Bolsen, 2003). The hghest EE nSapenza and Bolsen, 2003). The hghest EE n ths experment was 1.70% ndcatng a good qualty of slage.
Fber compostons of slages were not affected sgnfcantly by treatments (Table 3). The use of rce straw as slage materal ncreased the value of NDF, com-pared wth slages wthout rce straw (T2 vs T1, T4 vs T3, T7 vs T6), and also ncreased lgnn content of slages except for T2. Neutral detergent fber (NDF) s related to the fllng effects of feeds n the rumen. Pollard addton (T5 and T6) resulted n the lowest NDF, ADF, cellulose and lgnn contents n slage, but exhb-tng the hghest level of hemcelluloses (33.09%). Use of onggok as carbohydrate source resultng n the hghest cellulose content (49.55%) and lowest hemcellu-loses (4.18%).
Note: NDF= Neutral Detergent Fber; ADF= Acd Detergent Fber; T1= vegetable waste + rce bran; T2= vegetable waste + rce bran + rce straw; T3= vegetable waste + onggok; T4= vegetable waste + onggok + rce straw; T5= vegetable waste + pollard; T6= vegetable waste + pollard + rce straw.
Fber (%) Treatments
T1 T2 T3 T4 T5 T6
NDF 58.77 72.69 58.28 76.44 52.96 56.33
ADF 51.59 49.65 33.37 72.26 19.87 32.43
Hemcellulose 7.18 23.04 24.91 4.18 33.09 23.90
Cellulose 33.44 30.41 23.71 49.55 16.70 22.38
Lgnn 10.77 10.24 9.03 18.14 2.67 5.27
Conclusons
Physcal characterstc of vegetable waste slages was good, wth a yellowsh green colour and good aroma, ndcatng that fermentaton process was successful. Use of rce bran, onggok (cassava byproduct), and pollard as carbohydrate sources for enslng vegetable waste dd not show sgnfcant dfferences n chemcal and mcrobologcal characterstcs, nutrent and fber compostons of resulted slages. It can be concluded that all carbohydrate sources used n ths experment can be use as slage addtve resultng n a good vegetable waste slage.
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