特种油脂应用范围及发展前景的可研报告
Daim ntawv qhia txog kev ua tau zoo ntawm daim ntawv thov thiab kev loj hlob zeem muag ntawm cov roj tshwj xeeb thiab cov rog
第一节特种油脂的简介
特种油脂人造奶油从发明至今已有一百多年的历史。19世纪后期,普法战争期闶徬溔世法战争期闶徬溔不足,法国拿破仑三世悬赏招募,号召制造奶油的代用品。法国化学家梅吉。穆里斯于 1869年制成的奶油油获法国、英国专利。由于这种新产品的组成、外观綅幼与为“人造奶油”,它还有一名“麦淇淋”,是英文"Margarine" daim ntawv qhia.
Tshooj 1 Taw qhia txog cov roj tshwj xeeb thiab cov rog
Cov roj tshwj xeeb zoo li margarine, muaj ntau tshaj li ib puas xyoo ntawm keeb kwm los ntawm kev tsim khoom. Nyob rau hauv lub lig 19th caug xyoo, thaum lub sij hawm lub Franco-Prussian Tsov rog, Napoleon III ntawm Fabkis muab ib tug nqi zog los nrhiav ib tug hloov rau cov cream uas tsis muaj nyob rau hauv cov teb chaws Europe. Meggie, Fabkis kws tshuaj. Cov roj nplaum ua los ntawm Mullis hauv xyoo 1869 tau patented hauv Fabkis thiab Askiv. Raws li cov khoom tshiab zoo li butter nyob rau hauv ob qho tib si nws muaj pes tsawg leeg thiab tsos, nws yog hu ua "Margarine," thiab "margarine," uas yog ib tug transliteration ntawm lus Askiv margarine. (Feasibility Study Report)
第二节特种油脂的生产工艺
Tshooj 2 Kev tsim cov cuab yeej siv roj tshwj xeeb thiab cov rog
1.人造奶油生产工艺 Txheej txheem ntawm margarine
油相+水相 → 乳化 → 巴氏杀菌 → 急冷 → 捏合 人造奶油
Roj theem + dej theem → Emulsification → Pasteurizing → Quenching → Kneading → Margarine
2 .起酥油生产工艺 Txheej txheem ntawm shortening
基料油 → (乳化) → 急冷 → 捏合 起酥油
Base roj → Emulsification → Quenching → Kneading → Shortening
3 .代可可脂生产工艺 Txheej txheem ntawm cocoa butter hloov
氢化基料油 → 急冷 → 捏合 代可可脂
Hydrogenation puag roj → Quenching → Kneading → Cocoa butter hloov
乳化罐(人造奶油、起酥油〕、高压泵、急冷机、捏合机、背压阀、休止管酥皮油)
Emulsification tank (margarine & shortening), HP twj tso kua mis, votator, pin rotor tshuab, rov qab siab valve, so tube ( rooj margarine)
第三节 特种油脂的应用范围Daim ntawv thov ntawm cov roj tshwj xeeb
(ib) emulsifying tus neeg sawv cev
众所周知油、水是不相溶的,而我们的人造奶油是由油和水为主要的原料生产的,二徻滋是乳化剂的乳化作用所致。常用的乳化剂有Tus tsim tawm:
Raws li peb txhua tus paub, roj thiab dej yog insoluble, thiab peb margarine yog tsim los ntawm cov roj thiab dej ua cov ntaub ntawv tseem ceeb, ob qho tib si tuaj yeem ua ke zoo heev yog tshwm sim los ntawm emulsification ntawm emulsifier. Feem ntau siv emulsifiers yog raws li nram no:
1. Cov tshuaj monoglyceride
单甘酯是目前应用最广泛的乳化剂,是由甘油和油脂反应制得。产品有粉状、颗度可分为蒸馏单甘酯 (纯度40 ~ 50%) thiab未蒸馏单甘酯(纯度90%以上)。不溶于水,可溶于油脂(80℃以上)。。
Monoglyceride yog cov emulsifier siv dav tshaj plaws, uas yog npaj los ntawm cov tshuaj tiv thaiv ntawm glycerol thiab roj. Cov khoom nyob rau hauv hmoov, granular los yog muab tshuaj txhuam, raws li nws purity yuav muab faib ua distilled monoglyceride (purity 40-50%) thiab undistilled monoglyceride (purity ntau tshaj 90%). Insoluble hauv dej, soluble hauv roj (siab tshaj 80 ℃). Khaws nws kaw thaum khaws cia.
2. Cov tshuaj Lecithin
卵磷脂最初取自蛋黄,但由于其成本高且易腐败,生产中用大豆磷脂由代用卵磷。化脱胶的副产品,主要成分为卵磷脂、脑磷脂及肌醇磷脂。精制后呈半透明的粘稠液,在空气中或光线照射下迅速变黄,并逐渐的成渍透明的褐艶渍。性及乳化性,是良好的天然乳化剂。卵磷脂添加到人造奶油或起酥油中可增强稳定性,增加食品风味,还可防止烹调时溮兘,
Lecithin yog Ameslikas muab los ntawm cov qe qe, tab sis vim nws cov nqi siab thiab qhov tsis zoo, cov kua lecithin tau siv los ua ntau lawm. Soybean phospholipid yog ib yam khoom los ntawm cov kua txiv hmab txiv ntoo degumming. Nws cov khoom tseem ceeb yog lecithin, lecithin thiab inositol phospholipid. Cov kua nplaum nplaum uas hloov daj sai sai hauv huab cua lossis lub teeb thiab dhau los ua xim av opaque. Insoluble nyob rau hauv dej, zoo roj solubility thiab emulsification, yog ib tug zoo natural emulsifier. Lecithin ntxiv rau margarine lossis shortening tuaj yeem txhim kho kev ruaj ntseg, nce zaub mov tsw, tab sis kuj tseem tiv thaiv cov roj tawg thaum ua noj, cia yuav tsum tau shading, kaw.
3. Sucrose ester
蔗糖酯是一种高效而安全的表面活性剂,由蔗糖与脂肪酸反应制得,易溶于水,易溶于水,金制得,易溶于水。 ,145 ℃ 以上会分解。蔗糖酯与单甘酯并用可作人造奶油的乳化剂,对面包、蛋糕有抗老化作用。
Sucrose ester yog ib hom kev ua tau zoo thiab muaj kev nyab xeeb surfactant, npaj los ntawm cov tshuaj tiv thaiv ntawm sucrose thiab fatty acid, soluble hauv dej, tab sis tsis soluble hauv roj, ruaj khov ntawm 120 ℃, yuav decompose saum 145 ℃. Sucrose ester thiab monoglyceride tuaj yeem siv los ua emulsifier ntawm margarine, uas muaj kev tiv thaiv kev laus ntawm qhob cij thiab ncuav mog qab zib.
4.SPAN (司盘 / 失水山梨醇脂肪酸酯 Sorbitol fatty acid ester)
失水山梨醇脂肪酸酯是由山梨糖醇与脂肪酸反应制得的一类物质,其中我司姸有用。 52 -54 ℃ , 酸值 5 ~ 10 , SPAN65 则分别55-57℃、12-15,二者碘值均小于2。。。。性是对油脂结构有稳定作用,可使急冷后的油脂稳定在β′晶体结构.
Sorbitol fatty acid ester yog ib yam khoom uas npaj los ntawm cov tshuaj tiv thaiv ntawm sorbitol thiab fatty acid, cov uas SPAN60 thiab SPAN65 feem ntau siv los ntawm peb lub tuam txhab. Lub melting point ntawm SPAN60 yog 52-54 ℃, tus nqi kua qaub yog 5-10, thiab cov kua qaub ntawm SPAN65 yog 55-57 ℃ thiab 12-15 raws li, thiab tus nqi iodine ntawm ob qho tib si tsawg dua 2. Dawb lossis daj. dawb, zoo thermal stability, nyuaj rau yaj hauv dej, yooj yim rau yaj hauv cov roj thaum rhuab. Cov yam ntxwv tseem ceeb tshaj plaws yog kom ruaj khov rau cov qauv roj, uas tuaj yeem ua rau cov roj ruaj khov hauv β 'crystal qauv tom qab quenching.
Cov tshuaj tiv thaiv antioxidant
氧化是导致人造奶油、起酥油品质劣化的重要因素,防止氧化,除了虑选用原喙、存条件外,还可添加一些安全性高、效果显著的抗氧化剂。抗氧化剂的效果与油脂的种类、精炼程度、FFA的含量、铜铁离子、水分、光线、接触空气及温度有关縂姸劦。
Oxidation yog ib qho tseem ceeb uas ua rau qhov tsis zoo ntawm margarine thiab shortening. Txhawm rau tiv thaiv oxidation, ntxiv rau kev txiav txim siab xaiv cov khoom siv raw, cov txheej txheem ua, ntim thiab khaws cia, qee qhov kev nyab xeeb thiab zoo antioxidants kuj tuaj yeem ntxiv. Cov nyhuv ntawm antioxidants nyob ntawm seb hom roj, qib ntawm refining, FFA cov ntsiab lus, tooj liab thiab hlau ions, ya raws, lub teeb, raug huab cua, thiab kub. Peb feem ntau siv cov tshuaj antioxidants yog raws li hauv qab no:
1.BHA (丁基羟基茴香醚)
白色或微黄色蜡状结晶粉末,有特异的酚类臭味和刺激性气味,气味,憔点57-65 ℃,与 不溰 , 与 不溰30 ~ 40%, 热稳定性好, 弱碱下不易被破坏,可用与培烤食品,抗菌能力强。BHA和其它抗氧化剂混合使用,或与幬效用,或与幬效Qhov hnyav 0.2g / Kg /Kg.
Dawb los yog yellowish waxy crystalline hmoov, nrog tshwj xeeb phenolic tsw thiab pungent tsw, melting point 57-65 ℃, insoluble nyob rau hauv dej, 25 ℃ roj solubility 30-40%, thermal stability, tsis muaj zog alkali tsis yooj yim rau kev puas tsuaj, yuav ua tau siv nrog ci zaub mov, muaj zog antibacterial muaj peev xwm. BHA tseem zoo dua thaum siv ua ke nrog lwm cov tshuaj antioxidants lossis nrog citric acid, ib qho kev sib koom ua ke. Qhov ntau npaum li cas yog 0.2g / Kg hauv roj thiab 0.1g / Kg hauv margarine.
2.BHT (丁二基羟基甲苯)
白色结晶或粉末,无味,无臭,熔点69.5-70.5℃,沸点265℃,不溶于水,25 ℃ 豉油䶸年 4% ℃油中40%, 热稳定性好,具升华性,无BHA的异臭,价格低廉,毒性相对BHA高,抗氧化能力强.油脂中最魶魏人。 .1g/Kg, 与BHA, 柠檬酸合用以" BHT:BHA:柠檬酸=2:2:1"比例为佳.
Dawb siv lead ua los yog hmoov, tasteless, tsw, melting point 69.5-70.5 ℃, boiling point 265 ℃, insoluble nyob rau hauv dej, 25 ℃ soybean roj soluble 30%, paj rwb roj 20%, 40 ℃ lard 40%, thermal stability, sublimation, tsis muaj BHA heteroodor, tus nqi qis, toxicity txheeb ze rau BHA siab antioxidant muaj peev xwm. Qhov siab tshaj plaws ntawm cov rog yog 0.2g / Kg, margarine yog 0.1g / Kg, thiab qhov piv ntawm BHT: BHA: citric acid = 2: 2: 1 yog qhov zoo tshaj plaws thaum ua ke nrog BHA thiab citric acid.
3.TBHQ〔特丁基对苯二酚)
一种新型抗氧化剂,抗氧化效果比BHA、BHT好,最大特点Fe离子存在下不着色。TBHQ渍姺䰔或异臭,油溶性良好,熔点126.5-128.5℃,可单独使用,也可与BHT、BHA混用,油中最大添加量0.02%.
Ib hom tshuaj antioxidant tshiab, cov nyhuv antioxidant zoo dua li BHA, BHT, tus yam ntxwv loj tshaj ntawm Fe ion nyob rau hauv lub xub ntiag ntawm tsis muaj xim. TBHQ yuav tsis tsim cov ntxhiab los yog heteroodor thaum ntxiv rau cov roj, thiab cov roj muaj cov solubility zoo. Lub melting point yog 126.5-128.5 ℃. Nws tuaj yeem siv ib leeg lossis sib xyaw nrog BHT thiab BHA, thiab qhov siab tshaj plaws ntxiv hauv cov roj yog 0.02%.
Synergist-citric acid
两种或两种以上抗氧化剂混合使用,或与增效剂并用,往往比单独一种使用槈朞为增效作用。在植物油中使用酚型抗氧化剂,若同时添加柠檬酸,其抗氧化效果将显著提高。一般认为柠檬酸能和促进氧化反应的微量金属爐离子。 ,从而对促进氧化的金属离子起钝化作用。增效剂的用量一般是酚型抗氧化剂的1/4-1/2.
Kev sib xyaw ua ke ntawm ob lossis ntau dua antioxidants, lossis ib tus neeg sib koom ua ke, feem ntau zoo dua li ib leeg, ib qho tshwm sim hu ua synergism. Yog tias citric acid ntxiv rau cov roj zaub, cov nyhuv antioxidant ntawm phenolic antioxidants yuav zoo dua. Nws feem ntau ntseeg tias citric acid tuaj yeem tsim chelates nrog cov kab hlau ions (Cu2+, Fe3+) uas txhawb oxidation, yog li passivating hlau ions uas txhawb oxidation. Qhov ntau npaum ntawm cov synergist feem ntau yog 1/4-1/2 ntawm cov phenolic antioxidant.
(四) 防腐剂 Preservative
人造奶油中的水,尤其是水相中的一些物质。。具有杀死微生物或抑制微生繁殖的物质.
Cov dej hauv margarine, tshwj xeeb tshaj yog qee yam khoom nyob rau hauv cov dej theem (xws li whey hmoov), tshwj xeeb tshaj yog rau cov microbial reproduction thiab kev loj hlob. Preservatives yog cov khoom uas tua cov kab mob los yog inhibit lawv kev loj hlob.
1.Nyob ntsev
盐既是调味剂又是优良的防腐剂,盐的贮存要注意防止受污染和防潮.
Ntsev yog ob qho tib si flavoring tus neeg sawv cev thiab ib qho zoo heev preservative. Ntsev cia yuav tsum tau ceev faj kom tsis txhob muaj kab mob thiab tsis muaj dej noo.
2 .山梨酸钾 Potassium sorbate
无色或白色鳞片状结晶或粉末,无臭或稍有臭味,在空气中不稳源,可被氧化着可被氧化着水,对霉菌、酵母及好气性菌均有抑制作用,属酸性防腐剂,宜在PH值5-6以下范围内使用。贮存时注意防潮、密封。
Cov xim tsis muaj xim lossis dawb scaly crystals lossis hmoov, tsis muaj ntxhiab lossis tsw ntxhiab me ntsis, tsis ruaj khov hauv huab cua, tuaj yeem ua xim los ntawm oxidation, hygroscopic, yooj yim soluble hauv dej, muaj cov nyhuv inhibitory ntawm pwm, poov xab thiab aerostatic kab mob, yog ib qho acidic preservative. siv nyob rau hauv tus nqi PH ntawm 5-6 hauv qab qhov ntau. Ua tib zoo saib xyuas cov dej-pov thawj thiab sealing thaum khaws cia.
(五)色素 Pigment
1.β-胡萝卜素 Beta carotene
β-胡萝卜素为理想的天然色素,具价格低、有营养、色调稳定等优炫红紫艶粻朚。异臭,不溶于水和甘油,难溶于乙醇、丙酮,240 ℃ nyob rau hauv 植物油中溶解度为0.05-0.10%.贮存时要置于阴凉处,并注意遮光、密闭。
β-carotene yog ib qho zoo tagnrho natural pigment, uas muaj qhov zoo ntawm tus nqi qis, khoom noj khoom haus thiab xim stability. Reddish ntshav mus rau tsaus liab crystalline hmoov, me ntsis heteroodor, insoluble nyob rau hauv dej thiab glycerol, insoluble nyob rau hauv ethanol, acetone, solubility ntawm 0.05-0.10% nyob rau hauv zaub roj ntawm 240 ℃. Beta-carotene tsis ruaj khov rau ob lub teeb thiab oxygen thiab ua xim sib dua thaum raug cov hlau hnyav xws li Fe3+. Cia yuav tsum tau muab tso rau hauv qhov chaw txias, thiab xyuam xim rau shading, airtight.
2. 胭脂红 Carmine
红色或深红色粉末,无臭,溶于水呈红色,不溶于油,耐光性,耐酸性好,耐玀迟槀。性差,遇碱变褐色。吸湿性强,宜贮存于干燥、阴凉处、长期保存、应注意密封、防潮、防变质。
Liab los yog tsaus liab hmoov, tsw tsw, liab nyob rau hauv dej, insoluble nyob rau hauv roj, lub teeb tsis kam, zoo acid kuj, tshav kub tsis kam, txo tsis kam, tsis zoo kab mob kuj, alkali tig xim av. Cov cuab yeej hygroscopic muaj zog, yuav tsum tau muab cia rau hauv qhov chaw qhuav, qhov chaw txias, khaws cia ntev, yuav tsum tau them sai sai rau kev sib khi, noo noo-pov thawj, tiv thaiv deterioration.
3.柠檬黄 Txiv qaub daj
橙黄色粉末,无臭,0.1%水溶液呈黄色,不溶于油脂,耐热性、耐酸性、耐盐性姰好遇碱变红色。贮存注意事项同胭脂红.
Txiv kab ntxwv daj hmoov, tsw ntxhiab, 0.1% dej tov daj, insoluble nyob rau hauv cov roj, tshav kub tsis kam, acid kuj, ntsev kuj zoo, oxygen kuj, alkali kuj tsis zoo, tig liab thaum alkali. Kev ceev faj cia yog tib yam li carmine.
(六) 风味添加剂 Flavour agent
1. Ntxim qab heev
食用香精是用各种安全性高的香料和稀释剂等调和而成,可分为油溶性帀水。透明液存在,但以精炼植物油为稀释剂的油溶性香精低温时会出现冷凝现象。所有香精都有一定的挥发性,贮存时要注意置于阴凉处 3 幺 ℃晒、防潮、防火。香精启封后,不宜继续贮存,最好尽量用完。热敏性物料,使用时注意投入时间,并要注意使其在物料中均匀分希。
Khoom noj khoom haus tsw yog ua los ntawm ntau yam txuj lom thiab diluents nrog kev nyab xeeb siab, uas tuaj yeem muab faib ua ob pawg: roj soluble thiab dej soluble. Feem ntau ntawm lawv muaj nyob rau hauv cov kua ntshiab thiab pob tshab, tab sis cov roj soluble essence nrog refined zaub roj raws li diluent yuav condense ntawm tsawg kub. Tag nrho cov flavours muaj qee yam tsis hloov pauv, khaws cia yuav tsum tau them sai sai rau muab tso rau hauv qhov chaw txias (10-30 ℃ yog qhov tsim nyog), thiab ua tib zoo saib cov tshuaj pleev thaiv hnub, tiv thaiv dej noo, tiv thaiv hluav taws. Flavor tom qab qhib, yuav tsum tsis txhob khaws cia ntxiv, nws yog qhov zoo tshaj plaws los siv. Thaum tshav kub kub rhiab heev cov ntaub ntawv, xyuam xim rau lub sij hawm input, thiab xyuam xim kom nws tusyees faib nyob rau hauv cov khoom.
2.Nyob ntsev
如前所述盐既是防腐剂,又是风味调节剂。其既具有防腐作用,又具有使奶沸具有使奶沸具的熔点较低,食盐添加量少;夏季原料油脂的熔点较高,食盐添加量较多。食盐的贮存要注意防潮.
Raws li tau hais ua ntej, ntsev yog ob qho tib si preservative thiab tsw regulator. Nws muaj lub luag haujlwm ntawm preservative, tab sis kuj muaj kev ua haujlwm ntawm kev ua cov nplaum nplaum. Nyob rau lub caij ntuj no, lub melting point ntawm cov roj nyoos yog qis dua thiab cov ntsev ntxiv tsawg dua. Nyob rau lub caij ntuj sov, lub melting point ntawm cov roj nyoos yog siab dua thiab cov ntsev ntau dua. Ntsev yuav tsum tau khaws cia tiv thaiv noo noo.
3. 乳清粉 Whey mist
在人造奶油中添加乳清粉是为了加其风味性。乳清粉的主要成分是蛋白质,其姝有不可逆的特性,在贮存和使用中要尤其注意。具体影响因素如下:
Whey hmoov yog ntxiv rau margarine los txhim kho nws cov tsw. Lub ntsiab tivthaiv ntawm whey hmoov yog protein, uas yog hloov tau thiab irreversible nyob rau hauv tej yam kev mob. Kev saib xyuas tshwj xeeb yuav tsum tau them rau nws hauv kev khaws cia thiab siv. Tej yam cuam tshuam tshwj xeeb yog raws li hauv qab no:
(1) 化学因素:酸、碱、有机溶剂、重金属盐类、表面活性剂等。
(2) 物理因素:加热(高温)、紫外线、超声波、强烈的搅拌、振荡、挤压、各种射线。
(1) Tshuaj lom neeg: acid, puag, organic hnyav, hnyav hlau ntsev, surfactants, thiab lwm yam.
(2) Cov yam ntxwv ntawm lub cev: cua sov (siab kub), ultraviolet, ultrasonic, khaus agitation, oscillation, extrusion, ntau yam rays.
4. 乳脂 Butterfat
乳脂是天然的奶油,为了增加人造奶油的营养和风味而添加。低温、阴凉、干燥处存
Butterfat yog ntuj qab zib, ntxiv rau kev noj haus thiab tsw ntawm margarine. Khaws rau hauv qhov chaw txias, txias thiab qhuav.
Tom ntej: Deformer-Silicone emulsion
在食品煎炸生产中,有时会产生大量的泡沫,若不及时消泡,则油或泡沫会会低内妍席造成生产事故。我司生产的“KFC”煎炸油中添加乳化硅油,就是利用了它的消泡作用。
乳化硅油为乳白色油状液体,其粘度受温度影响不大,不燃,在空气中不挥发、性空樚蠔中不挥发。可溶于水.
Hauv kev tsim cov khoom noj kib, qee zaum yuav muaj ntau cov npuas dej, yog tias tsis ua raws sijhawm, cov roj lossis ua npuas dej yuav dhau los ntawm lub thawv, cuam tshuam kev ua haujlwm, thiab tseem ua rau muaj kev sib tsoo ntau lawm. Emulsified silicone roj yog ntxiv rau "KFC" roj kib ua los ntawm peb lub tuam txhab, uas ua rau siv nws cov nyhuv defoaming.
Emulsified silicone roj yog cov kua roj dawb, nws cov viscosity tsis cuam tshuam los ntawm qhov kub thiab txias, tsis muaj nplaim taws, tsis muaj hluav taws xob hauv huab cua, cov khoom ruaj khov, tsis muaj tshuaj lom, tsis muaj ntxhiab, soluble hauv dej.
第四节 特种油脂行业的发展前景 Kev loj hlob zeem muag ntawm kev lag luam roj tshwj xeeb
我国特种油品市场发展迅速,为与汽车配套使用的消费品,润滑油已经逐步转变为普通消费用品。现为普通消费用品。高,润滑油行业发展也随之兴起。机械化的程度越高,润滑油的使用率就越高,前景一片光明,渦油的使用率就越高。市场发展将趋稳增长.
我国特种油品行业需发挥雄厚科研技术力量优势,把握国际发展趋势,不断完善相关特种渇品力行业很少执行SH0040-91超高压变压器油标准,大部分采用符合国际标准的进口油。我姁油。对广阔的市场需求,迎来更好的机遇。
Kev lag luam roj tshwj xeeb tab tom txhim kho sai. Rau cov neeg siv khoom siv nrog lub tsheb, cov roj lubricating tau maj mam hloov mus rau cov khoom siv sib xws. Tam sim no nrog rau kev txhim kho ntawm qib mechanization, txoj kev loj hlob ntawm lubricating roj kev lag luam kuj nce. Qhov siab dua ntawm kev siv tshuab, kev siv cov roj lubricating ntau dua, qhov kev cia siab yog ci, kev loj hlob ntawm lubricating roj kev lag luam kev lag luam yuav ruaj khov.
Tuam Tshoj txoj kev lag luam roj tshwj xeeb yuav tsum tau muab kev ua si tag nrho rau qhov zoo ntawm kev tshawb fawb txog kev tshawb fawb thiab thev naus laus zis, tuav lub thoob ntiaj teb txoj kev loj hlob, thiab niaj hnub txhim kho cov txheej txheem ntawm cov khoom siv roj tshwj xeeb. Piv txwv li, Tuam Tshoj txoj kev lag luam hluav taws xob hluav taws xob tsis tshua muaj kev siv SH0040-91 ultra-high voltage transformer roj qauv, thiab lawv feem ntau txais yuav cov roj tuaj yeem ua tau raws li cov qauv thoob ntiaj teb. Tuam Tshoj cov tuam txhab roj tshwj xeeb yuav ntsib kev lag luam dav dav thiab ua rau muaj lub sijhawm zoo dua.
Post lub sij hawm: Dec-25-2022