动物营养学报2011,23(2):299—306 Chinese Journal ofAnimal Nutrition doi:10.3969/j.issn.1006-267x.2011.02.017 Effects of Yeast(Saccharomyces cerevisiae)and Yeast Extracts on Meat Quality of Broiler Chickens ZHANG Aiwu JU Guichun XUE Jun ZUO Luya DONG Bin (1.Chinese Medicine Materials College ofJilin Agricultural University,Changchun 130118,China;2.China National Group ofTraditional&Herbal Medicine,Beijing 102600,China) Abstract:The aim of the present study was to investigate the effects of yeast(Saccharomyces cerevisiae,SC) and yeast extracts(YE)on meat quality of broiler chicks.One hundred and eighty one—day—old male broiler chicks were randomly allotted into 3 treatments with 6 replicates each,and each replicate containing 10 birds.A 0.5%SC and a 0.3%YE were added to the control diets.respectively.The results showed as follows:com・ pared with the control,the ultimate pH(pHu)of drumstick meat treated wiht YE signiifcantly increased(P< 0.05),while the moisture content tended to increase and the cooking loss tended to decrease(P>0.05)of he tmeat treated with SC.The shear forces of both boiled and raw meat of SC—fed and YE—fed broilers signiicafntly decreased(P<0.05)compared wih tthe contro1.The 2一thiobarbituric acid—reactive substances(TBARS)value rteated wih tSC was signiifcantly lower(P<0.05)than the control after incubation.It can be concluded hatt the dietary SC and YE supplementation can improve the meat qualiy.t Both SC and YE can reduce the oxidation of meat and skin. Key words:Saccharomyces cerevisiae;yeast extract;pHu;cooking loss;shear force;TBARS value CLC number:¥831.5 Document code:A Article ID:1006-267X(2011)02-0299-08 In addition,yeast products can improve the anti—oxi- dative status of living animals and increase the oxida- tive stability of meat,which are considered to be bene— iciafl to the consumers and the processing industry[ . Saccharomyces cerevisiae(SC),one of the most commercialized yeast types,has been fed to animals for a long time[ .Previous researches had evaluated he effects of yeast products on performance and ilealt morphology of poultry[2-4]yet a few researches had ,The effect of yeast products on oxidative stability of chicken meat has not been extensively studied,albeit he yeastt culture supplementation in diet could increase been focused on the effects of yeast products on broil— er meat quality. Meat quality characteristics,such as tenderness, the anti—oxidative capacity of Cashmere goats_l1]. juiciness,drip—loss,cooking loss,pH,and shelf- life,are important to the consumers while purchasing the product as well as to the processors while process— Therefore,the present study was conducted to eval— uate the effects of SC and yeast extracts(YE)on meat quality of broiler chickens. ing the value—added meat products[ 一 show that the tenderness .Some trials and water holding capaci. 1 MATERIALS AND METHoDS 1.1 Birds,diets,and experimental design One hundred and eighty one—-day--old male broiler ty[ ]of the edible meat from broiler chickens is in— creased when fed a chromium—enriched SC diet Date received:2010—08—11 Financial support:The project sponsored by SRF for ROCS,SEM(2004001) Author information:ZHANG Aiwu(197l一),female,born in Licheng city of Shandong province,associate professor,major in animal nutrition E-mail:zhangaiwu@jlau.edu.cn 300 动物营养学报 23卷 chickens(Ross 308 strain)were randomly assigned to l8 wire-floored.suspended cages in a temperature— controlled room.Continuous lighting was provided throughout the experimental period.Room tempera— to make sure that the YE content was the same be. tween the two diets.and the yeast was cel1 wall—re— moved.Starter nd a15nisher diets were formulated(Ta— ble 1)and used as a control diet(without the addition of SC or YE .SC and YE were added to the control diet at the expense of soybean mea1.respectively.The ture was decreased from 32℃on d 0 to 25℃on d 21 and was kept constant thereafter,and d 0 was the day when eggs were hatched out.There were 3 dieta— ry treatments with 6 replicates each,and each repli— cate contained l0 birds.The 3 treatments consisted of a control diet.a 0.5%SC diet and a 0.3%YE diet colony—forming units(cfu)of SC were counted to be 1.3×10 cfu/g.Feed and water was provided ad libi. turn throughout the 35一day feeding tria1. Table 1 Composition and nutrient levels of the diets(DM basis) % )Provided the following per kilogram of diet:vitamin A 5 500 IU,vitamin D3 1 100 IU,vitamin E 11 IU,vitamin B12 0.006 6 mg,riboflavin 4.4 mg,pantothenic acid 11 mg(Ca—pantothenate 11.96 mg),choline 190.96 mg(choline chloride 220 m2),menadi0ne 1.1 mg(menadione sodium bisulifte complex 3.33 mg),folic acid 0.55 mg,pyridoxine 2.2 mg(pyridoxine hydorehloride 2.67 mg),biotin 0.1 1 mg,thiamin 2.2 mg(thimian mononitrate 2.40 mg),ethoxyquin 125 mg・ )Provided the following per kilogram of diet:Mn 120 mg,Zn 100 mg,Fe 60 mg,Cu 10 mg,1 0.46 mg,Ca 150 to 180 mg・ ME is a calculated value.and other nutrients are analyzed values. 1.2 Collection of meat and skin samples On the last day of the 35一day feeding trial,1 bird from each cage was selected randomly and euthanized by cervical dislocation.Immediately after slaughter, determined.The rest of the raw meat and skin sam- pies were stored at一20℃for the lipid oxidation as- say. 1.3 Determination of pHu Approximately 10 g of the ground breast and drum。 stick meat was homogenized in 50 mL distilled water 24 h after slaughter[ .the entire breast and drumstick meat(with skin)were sampled.One half of the raw breast and drumstick meat were sampled nd astored at4℃before the pHu. moisture content,cooking loss and shear force was The pHu of the homogenate was measured using a portable pH meter(HI8424, 2期 ZHANG Aiwu et al:Effects of Yeast(Saccharomyces cerevisiae)and Yeast Extract on Meat Quality of… 301 Beijing Hanna Instruments Science&Technology Co. homogenized.Four subsamples from each breast and Ltd.,Beijing,China). 1.4 DeterminatiOn Of moisture content In order to determine the moisture content,5 g of drumstick sample(i.e.72 breast meat subsamples and 72 drumstick meat subsamples),weighing印一 proximately 2.5 g,were placed into 50 mL screw- breast and drumstick meat sample was dried at 105℃ f0r 24 h[ 引.capped centifruge tubes and then incubated at 30℃ or 0,l ,3,6,10,15 afnd 21 d.After incubation, The weight of samples before and after dried was recorded. each subsample was immediately subjected to a ma— londialdehyde acid(MDA)assay to determine the extent of lipid oxidation.The TBARS values were ex— pressed as mg MDA per kg sample.The determina— The moisture content(%)=[(weight before嘶ed— weight after dried)/weight before dried]×100. 1.5 Determination of cooking loss The cooking loss was determined according to the procedure of Sen et a1.[14]Each breast and drum— .tion of oxidative stability in skin samples was the same as breast and drumstick samples except for the homogenization.Intact skin samples were incubated stick meat sample was sealed in a vacuum plastic bag and boiled in a water bath without pressure for 20 min rom 0 to 21 d.Affter incubation,skin samples were immediately homogenized with 6 mL 20%trichloro— acetic acid and processed as described above to deter— mine the TBARS values. until an intemal end point temperature of 70℃was reached(which was measured using a digital probe thermometer).Each piece of the meat was cooled, removed from the bag and weighed.The weight of samples before and after cooking was recorded. 1.8 Statistical analysis All data were evaluated by One--way ANOVA u—- sing the GLM procedure of SAS 7.0.Significant The cooking loss(%)=[(weight before cooking—-weight after cooking)/weight before cook-- differences of mean TBARS values among dietary treatments were analyzed by repeated measures and Tukey’s test in GLM procedure.The level of statisti— cal significance was preset at P<0.05. ing]×100. 1.6 Determination of shear force To determine the shear force of breast and drum— stick meat,boiled meat samples were used for cook— ing loss assays and the raw meat samples were cut in— 2 RESULTS 2.1 pHu The pHu of breast and drumstick meat of each to squares(35 mill×25 mm×6 nlin) .An appli— cation of cutting force to meat samples was performed using a TA—XT2 texture analyzer equipped with a TA一 reattment were shown in Table 2.There was no sig. nificant difference in the pHu of breast meat from 7 Warner—Bratzler blade(Stable Micro Systems Ltd. Surrey,England,UK). 1.7 Determination of 2-thiobarbituric(TBARS) value acid.reactive substances The raw breast and drumstick meat samples that broilers fed different sources of yeast(P>0.05). But the pHu of drumstick meat from YE—fed broilers were significantly higher than those of the control (P<0.05). had been stored at一20℃were thawed at 4℃and Table 2 Effects of SC and YE on pHu of male broiler chickens % Values are expressed as“means±SD”of six replicates of each dietary treatmentMeans in the same row wih no common lettter .superscripts differ signiifcantly(P<0.05).The same as below. 302 2.2 Moisture content 动物营养学报 23卷 content of breast and drumstick meat(P>0.05).Al— though there was no significant difference among the hree ttreatments,an increasing trend Can be observed in SC and YE treatments. Effects of SC and YE on moisture content of breast and drumstick meat were summarized in Table 3.Di. etary SC and YE had no significant effect on moisture Table 3 Effects of SC and YE on moisture content of male broiler chickens % 2.3 Cooking loss There was no signiicantf difference in cooking hough there was no signifticant difference in cooking loss of these three treatments(P>0.05),a decrea— sing trend Can be observed in SC and YE treatments. loss between breast and drumstick meat(P>0.05) from the three dietary treatments(Table 4).A1・ Table 4 Effects of SC and YE on cooking loss of male broiler chickens % 2.4 Shear force Effects of SC and YE on shear force in the raw he sheatr force of SC was significantly lower than that of the control(P<0.05),and YE was intermediate. For boiled meat,the shear force of breast and drum— stick meat of SC..fed and YE—-ed birds significafntly nd boiled breast aand drumstick meat were shown in Table 5.There was no significant difference in shear force of raw breast meat among all treatments(P> decreased compared wih tthe control(尸<0.05). 0.05).However,in raw drumstick meat samples, Table 5 Effects of SC and YE on shear force of male broiler chickens g 2.5 TBARS values There were no significant differences in TBARS of SC and YE were signiifcantly lower(P<0.05) han tthat of the contro1.On d 21 of incubatiOn. TBARS values were not significantly different be— values of breast meat(P>0.05)among the three rteatments up to d 6 ofthe incubation(Fig.1).On d l0.15 and 21 of the incubation,the TBARS values tween SC and YE(P>0.05).Up to d 3,no signifi— cant difference was found in TBARS values of drum— 2期 ZHANG Aiwu et al:Effects of Yeast(Saccharomyces cerevisiae)and Yeast Extract on Meat Quality of… ,v口 III)/∽0 一 ∽ ∞ 303 吕_)/s0三 ∽ 一 《口 stick meats(P>0.05)among the three treatments (Fig.2).On d 6,10,15 and 21,113ARS values were 1ower(P<0.05)in SC and YE thall those in the contro1.On d 21 of incubation.TBARS values were not significantly different between SC and YE f P> 0.051.There were no signiifcant differences for the skin 113ARS values(P>0.05)up to d 6(Fig.3). On d 6 and 10,TBARS values were significantly lower(P<0.05)in YE than those in the contro1.On d 15 and 21,TBARS values were significantly lower fP<0.05)in boch SC and YE than the contro1. 一 1"ime All data points are mean TBARS values from 6 replicates± standard deviation.The sanle time point with different smal1 letter superscripts mean signiifcant difference(P<0.05).The saltle as below. Fig.1 Effects of SC and YE on TBARS values in the breast meat of male broiler chickens Fig.2 Effects of SC and YE on TBARS values in the drumstick meat of male broiler chickens 3 DISCUSSION The pH is a direct reflection of muscle acid content and can affect the moisture content,cooking loss and shear force in meat.The pHu of drumstick meat from YE fed broilers in this study were signiifcant higher than those of the contro1.This might be related to the difference in muscle glycogen concentration .The pH decline depends on the muscle glycogen concen— tration.Daly et a1.118j also showed that a higher ini— tial muscle glycogen concentration resulted in a faster rate of pH decline.On the other hand,Campo et a1.[17]reported that this might be related to the differ. ence in stress susceptibility in pre-slaughter handling, and high pHu in the meat of YE--fed broilers sugges-・ ted that YE—fed broilers were generally highly prone t0 the stress. ^I 旨),}i0n1 ∞ 《mllIJ Time Fig.3 Effects of SC and YE on TBARS values in the skin of male broiler chickens A low pH is associated with poor water--holding ca-- pacity(WHC),which is also associated wiht lower moisture content.In this study,an increasing trend of moisture content could be observed in SC and YE rteatment.The results were in accordance with those obtained by Qiao et a1.[19]who reported that higher pH was generally associated wiht higher meat mois— ture content. The term,WHC,was originally used to describe hte ability of muscle and muscle products to bind wa— ter[2o],while cooking loss was measured to obtain an overall assessment of the water binding properties of meat.Samples with the lowest amount of cooking loss exhibited the highest amount of WHC.From a practical standpoint,cooking loss represents the most important parameter to the industry,which is looking for the raw materials with high moisture retention ca- pacity[21].In this study.a decreasing trend of cook. ing loss could be observed in SC and YE treatment.It <(1304 动物营养学报 23卷 suggested t|lat the meat of YE-fed and SC—fed broilers was prone to increasing its WHC.Madruga et a1.[ ] reported that differences in cooking loss were often ported that chromium yeast could enhance the capacity ofinhibiting the hydroxy radical(・OH)and resis— ting the superoxide anion radical(O ・)in the ser— linked to the differences in time and temperature of cooking,pHu and different fat contents.The pHu is known to influence the structure of myofibrils and consequently the WHC and cooking loss[23].These correlations were in agreement with previous find— ings【 , 一 】which were reported that the poultry meat with low pH was associated with low WHC,which resulted in increased cooking loss.The data from Ta— ble 2 and Table 4 were consistent wim previous stud— ies[ 一 ]that higher pHu were associated with higher WHC,i.e.,lower cooking loss. Tenderness is the sum of the mechanical strength of skeletal muscle tissue after rigor mortis during the postmortem storage .It is the most important tex. tural characteristic of meat and has the greatest influ- ence on consumer preference.Meat tenderness can be estimated by measuring the shear force,and lower shear force indicates tenderer meat.Our study sugges— ted that the dietary SC and YE can improve the ten— demess of broiler meat,although the underlying mechanism was not readily understood.There are some effective factors on the tendemess of meat.Du et a1.[。 ]reported that it could be due to the changes in fatty acid compositions of muscle lipids.The more the saturated fatty acids content,the higher the melt- ing point of fat,and the harder the meat.Other rea— son could be due to the protein content in the meat, hte higher the protein content,the harder the meat af- ter cooking[30].It suggested that SC—fed and YE—fed broilers prone to changing the compositions of muscle which need to be further studied.In addition,another reason could be due to the changes in pHu.Silva et a1.[31]reported that the tenderness depends on pH. The present results(Table 2 and Table 5)were in ac— cordance wiht the results reported by Froning et a1.[ ]and Silva et a1. that the meat with higher pHu had higher tenderness. The results(Fig.1,Fig.2,and Fig.3)provided evidence that the SC and YE could improve the oxida— tive stability of broiler meat.Zhang et a1.[32]also re. um and liver,reduce the MDA content,increase the activities of GSH Px and T.SOD in the serum and liver of heat stressed broilers.In the present study,Fig.1, Fig.2,and Fig.3 showed that the oxidation rates were the same among all treatments at the early stage of incubation.However,the oxidation rates were re— duced in SC and YE compared to the control at the later stage of incubation.indicating tI1at the meat from chicks fed SC and YE might contain less oxida- tive fat(or fatty acids).At present,a clear explnaa— tion for the anti—oxidative effect of SC and YE is not available,but it may due to the different oxidative fat or fatty acids contents between SC—-fed/YE--fed and the control broilers.Some researchers had reported htat lipid deposition in broiler chicks[。。一。 ]fed yeast diets is significantly lower than in chicks fed a corn— soybean meal diet.This would prove the above point. 4 CONCLUSIONS ①SC and YE can improve hte meat qualiyt. ②SC and YE can increase the meat tenderness. ③SC and YE can increase the anti—oxidative sta- bility of meat and skin of broilers,especially the YE. 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Effect offractions offish meal and hepatic lipid deposi- Poultry science,2002,81:428-433. tion in estrogenized chicks[J].Poultry Science,1984。 [30] JELENIKoVA J.PIPEK P.STARUCH L.The influ— 63:1020—1026. ence of ante.mortem treatment on relacionship between [35] TAKAHASm K.JENSEN L S.Eflfect of dietary com. pH and tenderness of beef[J].Meat Science,2008, position and estradiol implants on hepatic microsomal 80:870—874. mixed function oxidase and lipid deposition in growing [31] SⅡ VA J A,PATARATA L,MARTINS M.Influence chicks[J].Poultry Science,1984,63:2217—2224. of ulitmate pH on bovine meat tenderness during ageing 酵母(Saccharomyces cerevisiae)及酵母提取物对 肉鸡肉质的影响 张爱武 鞠贵春 薛军 左璐雅 董斌 (1.吉林农业大学中药材学院,长春130118;2.中国药材集团公司,北京102600) 摘 要:本文旨在研究酵母(Saccharomyces cerevisiae)及其提取物对肉鸡肉质的影响。试验采 用单因子随机分组,选取1日龄雄性肉鸡180只,随机分为3组,每组6个重复,每个重复l0只。 分别在基础饲粮中添加0.5%酵母和0.3%酵母提取物作为试验组饲粮。试验结果表明,饲粮 添加酵母提取物可显著增加肉鸡小腿肉的最终pH(P<0.05),同时饲粮添加酵母有增加肉中水 分含量及降低水煮失重率的趋势,但未达到统计学显著水平(P>0.05)。饲粮添加酵母及酵母 提取物与对照组相比均可显著降低生肉和熟肉的剪切力(P<0.05)。饲粮添加酵母与对照组相 比可显著降低TBARS值(P<0.05)。由此可知,饲粮添加酵母及酵母提取物可改善肉鸡肉质 和嫩度,同时酵母及酵母提取物均具有降低氧化的作用。[动物营养学报,2011,23(2):299- 306][中文全文见《动物营养学报》网站(WWW.China.JAN.corn)中文版2011年23卷2期] 关键词:酵母;酵母提取物;最终pH;水煮失重率;剪切力;TBARS值 作者,张爱武,副教授,E—mail:zhangaiwu@jlau.edu.ca (编辑王雯熙)