Effects of Adding Glucose, Sorbic Acid and Pre-fermented Juices on the Fermentation Quality of Guineagrass (Panicum maximum Jacq.

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1 808 Effects of Adding Glucose, Sorbic Acid nd Pre-fermented Juices on the Fermenttion Qulity of Guinegrss (Pnicum mximum Jcq.) Silges To Sho 1, N. Ohb, M. Shimojo nd Y. Msud* Lbortory of Animl Feed Science, Division of Animl Science, Deprtment of Animl nd Mrine Bioresource Sciences, Fculty of Agriculture, Kyushu University, Fukuok , Jpn 1 College of Animl Science nd Technology, Nnjing Agriculturl University No.1 Weigng Nnjing , P. R. Chin ABSTRACT : This study ws conducted to evlute the effects of dding glucose (G), sorbic cid (S), pre-fermented juice of epiphytic lctic cid bcteri (FJLB) nd their combintions on the fermenttion qulities nd residul mono-nd di-scchrides compositions of guinegrss silge. The dditives used in this experiment were 1% glucose, 0.1% sorbic cid nd FJLB t theoreticl ppliction rte of CFU g -1 on the fresh weight bsis of guinegrss, respectively. There ws totl of eight tretments in this experiment: (1) C (without dditives), (2) FJLB, (3) S, (4) G, (5) FJLB+S, (6) FJLB+G, (7) S+G, (8) FJLB+S+G. After 30 dys of storge, the silos were opened for chemicl nlyses. Bsed on the results, ll dditives were efficient in improving the fermenttion qulity of guinegrss silge. This ws well indicted by significntly (p<0.05) lower ph nd BA content nd significntly (p<0.05) higher LA content in the treted silges except for the FJLB thn in the C. However, there ws only slight increse in LA for the FJLB s compred with the C, which might be due to the low WSC content of the originl guinegrss (34.4 g kg -1 ). When the FJLB+S nd FJLB+G were dded, there were significnt (p<0.05) decreses in ph nd significnt (p<0.05) increses in LA s compred with the FJLB lone. This indicted tht the G, S nd FJLB were of synergestic effects on the silge fermenttion qulity. The G combintion tretments including the G lone showed lrge improvements in the fermenttion qulity s compred with the tretments without the G. This suggested tht dding fermentble substrtes (G) to plnt mterils such s guinegrss, which contin low WSC, intermedite popultion of epiphytic LAB, CP nd DM content, is more importnt nd efficient for improving the fermenttion qulity of silges thn dding number of species of domestic LAB (FJLB) nd erobic bcteri inhibitor (S). (Asin-Aust. J. Anim. Sci Vol 17, No. 6 : ) Key Words : Guinegrss Silge, Glucose, Sorbic Acid, Pre-fermented Juices INTRODUCTION It is well known tht tropicl grsses re generlly considered to be prticulr chllenge in silge mking nd this is ttributble to two min fctors: first, they tend to hve low wter-soluble crbohydrte (WSC), secondly, there is essentil difference in physicl structure between temperte nd tropicl grsses; tropicl grsses often hve more porosity, corseness nd permebility thn their temperte counterprts (Ctchpoole nd Henzell, 1971). When tropicl grsses re ensiled, reltively lrge quntities of ir my be trpped in the grss mss. This cn result in more plnt respirtion nd erobic microorgnisms ctivity, nd consume more WSC, which re required by desirble lctic cid bcteri (LAB), cusing fermentble substrtes loss (Alli et l., 1985). Aerobic conditions cn be improved by proper ensiling, such s chopping, compction of the forge mss in the silo nd rpid seling of the silo fter it hs been filled, but tropicl grsses re usully more difficult to compress nd exclude ir completely (Ctchpoole nd Henzell, 1971). Improving the * Corresponding Author: Ysuhis Msud. Tel: , Fx: , E-mil: ymsudgr.kyushuu.c.jp Received June 25, 2003; Accepted Mrch 2, 2004 fermenttion qulity ws chieved by ensiling with some dditives such s glucose to increse the supply of vilble substrtes for the growth of LAB, sorbic cid to inhibit the ctivity of erobic microorgnisms nd decrese the loss of WSC in the erly stge of ensiling, nd the pre-fermented juice of epiphytic LAB (FJLB) to contin more species nd numbers of LAB resulting in fst cidifiction nd ph reduction. Glucose ddition is to compenste the WSC loss cused by the initil undesirble bcteri ctivity (yest, mold nd erobic bcteri) nd ensure tht sufficient mount of WSC remins t the vigorous stge of LAB growth nd produces lctic cid (LA) enough to decrese ph below 4.2. Advntges in dding glucose re demonstrted by mny reserches such s Ohym et l. (1971, 1973, 1975). Sorbic cid is commonly used s mold inhibitor in foods (Deuel et l., 1954; Slunkhe, 1956; Lcey, 1989). In ddition, potssium sorbte or sorbic cid (Woolford, 1975; Alli nd Bker, 1982; Httori et l., 1996; Ci nd Ogw, 1998) hs been shown to inhibit the growth of yests nd mold, nd used s n ingredient of commercil silge dditives. These reserchers used sorbte or sorbic cid s silge dditive to inhibit the erobic deteriortion, when the silo ws opened nd exposed to ir during the utiliztion period. In the present study, we used sorbic cid in order to

2 GUINEAGRASS SILAGES TREATED WITH SOME ADDITIVES 809 restrict the ctivity of erobic microorgnisms during the very erly stge of ensiling, nd decrese the loss of WSC. It ws well documented tht dding the FJLB to silges ws effective for improving fermenttion qulity, nd often resulted in the increse of LA nd in the reduction of mmoni-n (AN) even when the ddition of commercil LAB ws ineffective (Ohshim et l., 1997,b,c). In the present study, it is considered tht FJLB will promote the onset of LAB fermenttion, nd ccelerte the rte of LA production nd ph reduction, nd increse the efficiency of WSC utiliztion for LAB. There is, however, reltively little published informtion on the effects of sorbic cid, glucose, FJLB nd their combined tretments on the fermenttion qulities, especilly for tropicl grsses. The objectives of the present study re to evlute the effects of ddition of glucose, sorbic cid, FJLB nd their combined tretments on the fermenttion qulities nd residul mono- nd discchrides compositions of guinegrss silges. MATERIALS AND METHODS Additive preprtion The FJLB ws prepred from guinegrss ccording to the following mnners; 100 g smple of freshly cut guinegrss ws mcerted with 300 ml of distilled wter using blender. The mcerted smple ws filtered through double lyers cheesecloth, nd 200 ml of the filtrte ws collected into 500 ml glss bottle to which 4 g of glucose were dded. The glss bottle ws fitted with gs trp nd mintined t 30 C for 3 dys (Ohshim et l., 1997,b,c). After 3 dys of nerobic incubtion, the ph vlue nd the popultion of LAB of pre-fermented juice were determined just before being dded to the silge mteril. Silge mking Guinegrss ws cultivted in the experimentl field of Kyushu University, Hkozki, Fukuok, Jpn. The second growth of the guinegrss ws hnd-hrvested with sickle t the middle heding stge on September 4 in The hrvested grss ws immeditely chopped into bout 1cm length prior to tretments. The dditives used in the experiment were glucose 1% (G), sorbic cid 0.1% (S) nd FJLB t theoreticl ppliction rte of CFU g -1 on the fresh weight bsis of guinegrss, respectively. There ws totl of eight tretments in this experiment: (1) C (without dditives), (2) FJLB, (3) S, (4) G, (5) FJLB+S, (6) FJLB+G, (7) S+G, (8) FJLB+S+G. After thorough mixing, 630-g of guinegrss ws ensiled into lbortory silo (1 liter cpcity) in triplictes t ech tretment. This ws followed by being seled with screw top nd stored in the room kept t 25 C. All silos were opened fter 30 dys of storge. Chemicl nlyses The chopped guinegrss ws immeditely collected for the determintion of contents of dry mtter (DM), totl nitrogen (TN), crude protein (CP) mono-nd di-scchrides compositions (fructose, glucose nd sucrose), nd the popultion of epiphytic LAB in the initil guinegrss. After opening the silos nd mixing the content thoroughly, 50 g smple ws tken from ech silo nd 150 g of distilled wter ws dded before being stored in the refrigertor t 4 C for 24 h. Then, the extrcts were filtered through double lyers cheesecloth nd filter pper (Toyo No. 5A, Jpn), nd the filtrte ws used for the determintion of ph, AN, LA, ethnol nd voltile ftty cids (VFAs). The ph of silge ws mesured using glss electrode ph meter (Horib Co, Jpn). The TN contents of fresh guinegrss nd silges were nlyzed by the Kjeldhl method (AOAC, 1984) nd the CP of fresh grss ws determined with TN multiplied by The LA content ws determined using the method of Brker nd Summerson (1941), nd the contents of VFAs nd ethnol with gs chromtogrphy (Shimdzu, Jpn. GC-17A with 12 m cpillry column, condition: column temperture 100 C, injection nd detection temperture 250 C). The AN content with n mmoni electrode meter (Model IM-22P, To Electronics Ltd, Jpn). The DM contents of the fresh guinegrss nd silges were determined by drying in n oven t 60 C for t lest 48 h (AOAC, 1984), nd the DM of silges ws reclculted with the contents of voltile compositions. Mono-nd di-scchrides compositions of the fresh guinegrss nd silges were determined by high performnce liquid chromtogrphy (HPLC) s shown in previous report (Sho et l., 2002). The popultion of epiphytic LABs in the fresh guinegrss nd the FJLB ws determined by counting the CFU with GYP-CCO 3 gr plte (Msuko et l., 1992). Sttisticl nlyses Sttisticl nlyses included one-wy nlysis of vrince with tretments s fctor nd Fisher s lest significnt difference test; these were performed by ANOVA using the GLM procedure of the Sttisticl Anlysis System (SAS, 1984). RESULTS From the chrcteristics of the initil guinegrss nd FJLB in this experiment (Tble 1), it is pprent tht the guinegrss hd low contents of fructose (16.2 g kg -1 ), glucose (11.7 g kg -1 ), sucrose (6.4 g kg -1 ) nd totl monond di-scchrides (34.4 g kg -1 ), nd intermedite contents of CP (79.4 g kg -1 ) nd DM (290.1 g kg -1 ). The popultion of epiphytic LAB ws CFU g -1 for the fresh

3 810 SHAO ET AL. Tble 1. Chrcteristics of guinegrss nd FJLB 1 before ensiled Silge mteril FJLB Dry mtter Crude protein Fructose Glucose Sucrose Mono- nd di-scchrides LAB 2 LAB 3 (g kg -1 ) (g kg -1 DM) (g kg -1 DM) (g kg -1 DM) (g kg -1 DM) (g kg -1 DM) (CFU g -1 FW) (CFU ml -1 ph ) Pre-fermentted juice of epiphytic lctic cid bcteri. 2 The popultion of epiphytic lctic cid bcteri in initil fresh grss expressed s colony forming unit (CFU) per g fresh weight (FW). 3 The popultion of lctic cid bcteri in FJLB prior to being dded expressed s colony forming unit (CFU) per ml FJLB. Tble 2. Fermenttion qulity of guinegrss silges treted with glucose, sorbic cid, FJLB nd their combintions Item C FJLB S G FJLB+S FJLB+G S+G FJLB+S+G Dry mtter (SD) (g kg -1 ) (4.77) (1.34) (4.26) (6.85) b (6.01) (0.91) (4.06) b (3.62) ph (SD) 4.58 (0.17) d 4.17 (0.04) c 4.19 (0.10) c 3.86 (0.02) b 4.00 (0.04) b 3.85 (0.04) b 3.72 (0.02) 3.79 (0.03) Lctic cid (SD) (g kg -1 DM) 18.7 (4.62) 21.7 (4.96) b 32.7 (5.54) bc 61.8 (4.60) e 38.6 (5.31) c 44.4 (4.24) cd 55.4 (18.08) de 55.2 (12.13) de Acetic cid (SD) (g kg -1 DM) 13.6 (6.31) bc 14.2 (3.63) c 8.5 (2.74) b 9.1 (4.06) bc 9.5 (0.79) bc 11.5 (4.79) bc 7.4 (1.88) 7.4 (0.45) Voltile ftty cids (SD) (g kg -1 DM) 27.0 (2.72) d 18.1 (4.84) cd 14.3 (5.21) bc 10.5 (4.26) b 10.8 (1.70) b 12.2 (4.64) bc 8.8 (2.42) 7.9 (0.17) Butyric cid (SD) (g kg -1 DM) 12.5 (3.65) c 3.7 (1.43) b 5.1 (4.60) b 1.2 (0.47) 1.1 (1.62) 0.3 (0.22) 1.2 (1.59) 0.1 (0.20) Vleric cid (SD) (g kg -1 DM) 0.0 (0.04) 0.0 (0.00) 0.0 (0.00) 0.0 (0.00) 0.0 (0.00) 0.0 (0.07) 0.0 (0.00) 0.0 (0.00) Propionic cid (SD) (g kg -1 DM) 0.8 (0.04) b 0.2 (0.26) 0.7 (0.21) b 0.2 (0.43) 0.2 (0.41) 0.4 (0.48) 0.1 (0.24) 0.4 (0.41) Ethnol (SD) (g kg -1 DM) 11.7 (2.89) bc 9.8 (3.75) b 10.8 (3.68) b 17.0 (9.67) c 7.8 (1.24) b 14.4 (1.12) bc 7.3 (0.94) 10.8 (0.66) bc AN/TN (SD) (g AN kg -1 TN) 88.4 (24.42) bc 92.6 (19.22) c 70.6 (6.17) b 53.0 (7.14) 86.9 (14.26) bc 70.5 (12.87) b 65.5 (12.24) 62.5 (6.08) Lctic cid/cetic cid (SD) 1.4 (1.48) 1.5 (1.48) 3.9 (1.11) b 6.8 (3.61) c 4.1 (0.58) b 3.9 (2.40) b 7.5 (1.68) c 7.4 (1.34) c, b. c. Vlues followed by different letters in the sme row show significnt differences t p<0.05. C: control, FJLB: pre-fermented juice of epiphytic lctic cid bcteri, S: sorbic cid, G: glucose, AN: NH 3 -N, TN: totl N. guinegrss nd CFU ml -1 for the FJLB hving ph vlue of The fermenttion qulities of guinegrss silges treted with glucose, sorbic cid, FJLB nd their combintions re presented in Tble 2. The G nd S+G silges significntly (p<0.05) incresed DM content, nd the other treted silges did not show significnt (p>0.05) differences s compred with the C. All treted silges showed significntly (p<0.05) lower ph vlues thn the C. When the FJLB+S nd FJLB+G were dded, there were significnt (p<0.05) decreses in ph s compred with the FJLB lone. Similrly the FJLB+S nd S+G silges lso significntly (p<0.05) decresed ph s compred with the S lone. The G ddition showed significntly (p<0.05) lower ph thn the FJLB nd S dditions. There were no significnt (p>0.05) differences between the G lone nd G combintion silges, but they hd the lrgest ph reduction s compred with the other treted silges. With the exception of the FJLB, ll treted silges significntly (p<0.05) incresed LA content s compred with the C. The FJLB+S nd FJLB+G silges hd significntly (p<0.05) higher LA content thn the FJLB lone. The S+G silge showed significntly (p<0.05) higher LA content nd the FJLB+S tended to increse (p>0.05) it s compred with the S lone. The G nd G combintion tretments (FJLB+G, S+G, FJLB+S+G) gretly improved the fermenttion qulity of silge with lrger LA production thn the silges without the G. There were not significnt (p>0.05) differences in LA content mong the G, S+G nd FJLB+S+G treted silges, but the FJLB+G hd significntly (p<0.05) lower LA content s compred with the G lone. The S+G nd FJLB+S+G silges significntly (p<0.05) decresed AA content s compred with the C nd FJLB. The other treted silges did not show significnt (p>0.05) differences in AA content from the C. With the exception of the FJLB ll treted silges significntly (p<0.05) decresed the content of VFAs s compred with the C. Silges treted with the S+G nd FJLB+S+G showed the lowest VFAs tht were significntly (p<0.05) lower thn the C, FJLB nd S treted silges. There were no significnt (p>0.05) differences mong the other treted silges in VFAs content. When dditives were given, there were significnt (p<0.05) decreses in BA content s compred with the C. However, the S or FJLB hd significnt (p<0.05) or slight (p>0.05) increse in BA content thn the other treted silges. The vleric cid (VA) ws hrdly found in ll silges. There were very low levels of propionic cid (PA) in ll silges, but the C nd S showed slightly but significntly (p<0.05) higher PA thn the other treted silges. The ethnol content did not show significnt (p>0.05) differences mong ll silges except for the G nd FJLB+G tht hd higher tendency. When compred with 88.4 g kg -1 for AN/TN of the C, there were significnt (p<0.05) decreses in the G, S+G nd S+G+FJLB, respectively. The FJLB+G ddition significntly (p<0.05) decresed AN/TN but the FJLB+S showed n insignificnt decrese (p>0.05) s compred with the FJLB lone. There were no significnt (p>0.05) differences in AN/TN between the FJLB+S nd S, nd between the S+G nd S. The FJLB nd C hd similr LA/AA. The S ddition tended to increse it s compred with the C, but there were significnt (p<0.05) increses in the G, S+G nd FJLB+S+G.

4 GUINEAGRASS SILAGES TREATED WITH SOME ADDITIVES 811 Residul crbohydrte frction compositions (g kg -1 DM) Crbohydrte frction Fructose Glucose Sucrose Crbohydrte frction b b b 0 Control FJLB Sorbic cid Glucose FJLB+Sorbic FJLB+Glucose cid Tretments Sorbic cid +Glucose FJLB+Sorbic cid+glucose Figure 1. Effect of dditives on the residul crbohydrte frction of guinegrss silges. FJLB: pre-fermentted juice of epiphytic lctic cid bcteri. Different letters in the sme frction show significnt differences t p<0.05. The dditions of the FJLB+S nd FJLB+G showed tendency of increse in LA/AA s compred with the FJLB lone. There ws not significnt (p>0.05) difference between the S lone nd FJLB+S, but the S+G showed significntly (p<0.05) higher LA/AA thn the S lone. The contents of residul mono-nd di-scchrides compositions re shown in Figure 1. The S+G nd FJLB+S+G dditions showed slightly but significntly (p<0.05) higher residul totl mono- nd di-scchrides contents. There were no significnt (p>0.05) differences in residul glucose, fructose nd sucrose mong ll silges tht showed very low contents except for the FJLB+S+G hving slight but significntly (p<0.05) higher sucrose content. DISCUSSION All treted silges significntly (p<0.05) decresed ph nd BA wheres significntly (p<0.05) incresed LA with the exception of LA in the FJLB s compred with the C. These indicted tht the dditives improved the fermenttion qulity. However, the FJLB ddition showed smll LA increse, which ws probbly cused by low WSC content of the originl guinegrss (34.4 g kg -1 ), rther thn the FJLB inoculnt itself. This is in greement with the report of Uchid nd Kitmur (1987), which showed tht LAB dditives did not hve lrge effect on fermenttion qulity of tropicl grss with low WSC content. Sele (1986) lso reported tht LAB inoculnt ws less effective if the fermentble substrte ws low or insufficient. When the FJLB+S nd FJLB+G were dded, there ws n evidence of further increse in LA nd decrese in ph s well s tendency of increse in LA/AA s compred with the FJLB lone. This indicted tht the S, G nd FJLB were of synergistic effects on the silge fermenttion qulity. Moreover, it lso indicted tht the efficiency of fermenttion in silges with the dditive of FJLB lone ws limited by low WSC content of the originl grss. This could probbly be explined s follows. First, the FJLB combined with G (FJLB+G) supplied the fermentble substrte for LAB to produce more mounts of LA, resulting in lower ph (Ohym et l., 1971, 1973, 1975). Second, FJLB combined with the S (FJLB+S) restricted the ctivity of erobic bcteri during very erly stges of ensiling, nd decresed the loss of WSC for LAB (Woolford, 1975, Alli et l., 1985). The S+G hd significntly (p<0.05) higher LA thn the S+FJLB nd S, but there ws not lrge difference (p>0.05) between the S+FJLB nd S. This indicted tht the S+G ddition ws more effective thn the S+FJLB nd S lone, becuse the low WSC content in the originl mteril ws the mjor limiting fctor in the effect on the fermenttion qulity. Although the S lone ddition decresed the loss of WSC from the undesirble bcteri ctivity, there ws not enough WSC for LAB s compred with the S+G ddition silge. The dditions of the G, S+G nd FJLB+S+G gretly incresed LA nd LA/AA nd decresed ph s compred with the other treted silges. This indicted tht these dditives further promoted homofermenttive LAB

5 812 SHAO ET AL. fermenttion s compred with the other treted silges. It ws confirmed tht dding the fermentble substrte (G) to the guinegrss ws more importnt nd effective to mke high qulity silges thn dding the FJLB nd S. The other treted silges showed insignificnt (p>0.05) increses in LA/AA compred with the C, suggesting tht these tretments without the G hd not enough mounts of fermentble substrtes to further increse the ctivity of homofermenttive LAB in the production of more LA. There ws n interesting result tht the G+FJLB silge showed lower LA nd LA/AA s well s tendency of higher AA thn the G lone. The increse of AA in the FJLB dditive silges ws lso found in other experiments (Ohshim et l., 1997,b,c), suggesting some herterofermentttive LAB ctivity occurring. This my be explined s follows. FJLB contin more species nd numbers of LABs from the originl grss, which ws different from the commercil LAB contining only homofermenttive LAB. When the FJLB ws dded to grss mss, the numbers of both homo- nd heterofermenttive LAB were enhnced, thus resulting in higher ctivity of not only homofermenttive LAB but lso heterofermenttive LAB. There were significntly (p<0.05) lower vlues of AN/TN in the G, S+G nd S+G+FJLB silges thn in the C. This indicted tht the rte of LA production nd tht of ph reduction were fster in these silges, thus inhibiting the ctivity of proteolysis by plnt enzymes nd other undesired bcteri ctivity during the erly stge of ensiling. The FJLB or S lone hd slightly higher BA or PA content thn the other treted silges, which indicted some clostridil bcteri ctivity occurring. This ws due to low WSC of the initil guinegrss, nd there were not sufficient LA nd enough low ph to inhibit the ctivity of clostridil bcteri during ensiling. Some reserchers (Yokot et l., 1991; Miygi et l., 1993) reported tht the ensiling nture of tropicl species ws LA-type fermenttion, but others (Ctchpoole, 1970; Ctchpoole nd Henzell, 1971; Pndithrtne et l., 1986; Kim nd Uchid, 1990) demonstrted tht min preservtion in silges mde from tropicl grsses ws AAtype. They suggested tht the WSC content of the originl grss might determine the LA or AA-type fermenttion. In the present study the guinegrss contined low mounts of WSC (34.4 g kg -1 ), but the LA content ws higher reltive to AA nd ethnol in ll silges, not the AA-type silge. This ws still not cler, but there ws probbly high ctivity of lctte producing bcteri dherent to the originl guinegrss ( CFU g -1 FW). There were very low contents of residul fructose, glucose, sucrose nd totl mono- nd di-scchride in ll silges. This indicted tht the WSC content of originl guinegrss ws low nd not dequte, therefore, lmost ll the fermenttion substrtes were consumed during 30 dys of ensiling. The S+G nd FJLB+S+G dditions showed slightly but significntly (p<0.05) higher sucrose nd totl mono-nd di-scchrides contents s compred with the other treted silges. This suggests tht the combintion of the G with S dditions improved the utiliztion efficiency of WSC compred with the G or S lone. Bsed on this study, ll dditives hd beneficil effect on the improvement of fermenttion qulity, but the FJLB lone hd less benefit s compred with the other dditives. The FJLB in the combintion with S or G further incresed LA content nd decresed ph vlue, nd which were the synergestic effects on the silge fermenttion qulity. Especilly the G nd G combintion tretments gretly improved the fermenttion qulity. These suggest tht dding fermentble substrtes (G) to plnt mterils such s guinegrss, which contin low WSC, intermedite popultion of epiphytic LAB, CP nd DM content, is more importnt nd efficient for improving the fermenttion qulity of silges thn dding number of species of domestic LABs (FJLB) nd erobic inhibitor (sorbic cid). REFERENCES Alli, I. nd B. E. Bker Effects of dditives on lctic cid production nd wter soluble crbohydrtes in chopped corn nd lflf. J. Diry Sci. 65: Alli, I., S. Pbri, R. Firbirn nd B. E. Bker The effects of sorbtes on the ensilge of chopped whole-plnt mize nd lucerne. J. Sci. Food Agric. 36: AOAC Officil Methods of Anlysis. 14th edn. Assocition of Officil nd Anlyticl Chemists, Arlington, Virgini Brker, S. B. nd W. H. Summerson The colorimetric determintion of lctic cid in biologicl mteril. J. Biol. Chem. 138: Ci, Y. nd M. Ogw Effect of mmonium tetrformte on the erobic deteriortion of corn silge. J. Jpn. Grssl. Sci. 44: Ctchpoole, V. 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