KET QUA NGHIEN CUU KH CN CUA VIEN CONG NGHE SAU THU HOACH NAM 2001
NGHIEN CUU CONG NGHE VA THIET BI SAY LONG NHAN Cao Van Himg, Dang Xuan Mai, Biii Kim Khanh, Nguydn Thi Tii Quynh,
Nguydn Thj Thu Trang, Dang Thi Thanh Quyen Be} mdn Bdo ipidn - Vien Cdng nghe sau thu hoach
May say long nhan ban co gieti true dirng quay SN-300 cdng suai 70kg/me dupe thiei ke phii hetp vdi qui mo hp gia dinh. Qua cac thi nghiem da xac dinh qui trmh say va xay dung dupe mo himh say nhu sau: Vdi long let cd hai qua trinh say. .Say 1 d nhiel dp 60"C tdi ham dm qua de' boc vd va hat la 40% vdi teic dp beic hoi aim la 1,02%/h, sau dd dem ciii sau say 1 di xdng hoi luu huynh lieu luimg 2 gam/0,.353m' trong 40 phut rdi lien hanh say 2 cung d 60"C cho de'n kho (35-37%) se cd long let chai lupng tdt nhai. Vdi long xoay cung co hai qua trinh say. Say 1 d nhiet dc) 120"C, say den ham dm cui 70% (trong khoang 30-35 phut) rdi chuydn sang sa'y 2 d 50-60"C cho den khd (35-37%) vcii tdc dp bdc hoi dm la 32% dm/h (ddi vdi say 1) va 2,69- 3,18% ain/h (ddi vdi say 2) se cho chai lupng long nhan xoay loi nhai. Chai lupng long nhan xoay dat duetc dc:p ve trang thai, hinh dang, mau sSc, hirong vi va dam bao ve sinh an loan thuc pham. Cong nghe say long nhan vcii thiei bi say SN300 nay da dupe trien khai va ap dung cho kei qua tdi.
L D A T V A N D E ''^r Say nhan la bien phap quan trpng trong chd bidn, bao quan va tieu thu nhan hien nay. Cd 3
loai long nhan (theo each gpi truydn thdng): long ttit, bach long va long xoay. Hien nay khdi lupng nhan say chiem 55-60% teing luctng nhan tuoi. Viii nam gdn day do md rpng quan he buPn ban vdi Trung qudc nen thj trudng nhan say khd da duoc hinh thanh, sd luemg san pham nay dang ngay cang lang. Udc tinh tai Hung Yen cd khoang 600 Id say thu cdng vdi nang suai 0,5-1,5 tan nhan tuoi/ld, ngay. Nhung Id say nay da mang lai ngudn thu dang kd cho ngudi ddu tu ma cdn gdp phan vao binh dn gia nhan. 6 phia Nam, viec say nhan khdng manh me nhu phia Bdc, nhan sir dung de say chii ye'u tai cac vimg trdng nhan long bdng cac Id sa'y thu cdng nen chat lupng san phdm khPng cao, cPng nghe say d mdi dja phuong mpt khae do thieu ky thuat hoac thPng tin can thiet nen ban chd chai lupng va su dn djnh chai lucmg. Da ed mpt vai chuydn giao ePng nghe giira nPng dan vdi ndng dan tir mien bdc de'n mien trung nudc ta nhung do thie'u ddng bp nen vdn chua dat yeu cdu mong mudn. Mat khac Id say thu cdng la khong ban che dupe tinh dn djnh cap nhiet, vdn dang sir dung khdi Id lam tac nhan say nen chat lupng san phdm khdng dam bao ve sinh an toan thuc phdm, rai cdn thiet nghien cuu de sir dung tac nhan say la khdng khi khd, ndng dd khdc phuc cac tdn tai tren. Theo thu thap nhidu ngudn thdng tin ngoai nudc trong thdi gian dai thi tren the gidi chua cd cae nghien ciiru vd cdng nghe va thidt bj say long nhan hoac chua phd bie'n nen rai thie'u nhirng thdng tin lam eo sd cho nghien curu. Nhung can cir vao eae ky thuat truyen thdng cd dien nudc ta ciing cac nghe; nhan truydn thd'ng trong linh vuc nay, chiing tdi tie'n hanh nghien ciiu cdng nghe va thidt bj say nhdm dat dupe qui trinh cPng nghe hoan chinh de dat dupe eae muc tieu sau;
Nang cao chat lupng san phdm vd cam quan nhu trang thai, hinh dang, mau sdc dac trung eua long nhan xoay nhdm nang eao gia trj va gia trj sit dung long nhan.
Dam bao ve sinh an loan thuc phdm cua san pham.
Giam thidu P nhidm mPi trudng do khdi bui ndng gay ra trong qua trinh say bdng Id thii cdng tai cac lang nghd say.
Tao ra md binh thiet bj say phii hpp ban co gidi qui mP hp gia dinh.
II. VAT LIEU VA PHUONG PHAP
- Tir thi nghem nhd den thi nghiem Idn trong phdng thi nghiem.
- Tir thi nghiem ldn den thuc nghiem nhd tai hien trudng.
- Tii thue nghiem nhd de'n trinh didn Idn tai cac co sd san xuat de danh gia ket qua va kha nang ap dung.
- Ket hpp nghien cihi vdi viec xay dung md hinh san xuat va chuyen giao tien bp ky thuat cho san xuat tai hp nPng dan.
- Sir dung phuong phap Tbi nghiem ye'u td va thidt ke thi nghiem ngdu nhien hoan toan.
- Tinh trung binh tdng the.
- Do lech tieu chuan tdng thd (dp lech mdu).
- Cae chi tieu phan tich chat lupng san phdm theo cac lieu chudn hien hanh.
- Nguyen lieu nhan; Vu nhan nam 2000 vdi cac gidng nhan mien Trung va mien Bdc dupe thu thap tir cac chp d Ha Npi va tai vudn nhan tinh Hung Yen.
III. KET QUA VA THAO LUAN 3.1. Long tet
Long tet dupe tao ra bdi say ca qua nhan (qua cdn vd, ciii, hat) dcii dci dm nhai dinh. sau dd tach vd, hat rdi lay ciii say ticp den khd
Cdi
t
Nhan qua — • Say I —•Tach vd, hat — • Xir ly — • Sa'y2 — • Long let
Vd, hat
3.1.1. Anh hudng ciia nhiet dp say qua den chat lupng ciii sau say 1 (long tet) Chat lupng ciii sau say 1 dupe bieu thj (Tinh theo thir tu uu tien) nhu sau:
- Trgng thdi: Trang thai ciii nguyen den den ciii nat irng vdi didm tir 5 den 1 - Mail sdc: Mau tir vang sang den iniiu den irng ve'ti dicm lir 5 don 1
- Tinh cd the chdp nhdn dugc: Chap nhan dupe den khong chap nhan dupe irng vdi diem tir 5 de'n I.
Nhan qua dupe phan loai. bd cudng, lam sach sau dd dem say. Say dupe lien hanh d cac nhiet dp say khac nhau 50, 60, 70, 80±rC irng vdi cac thdi gian khac nhau dd sao cho qua khd den mpt ham dm nhai djnh la 44±1% rdi lien hanh bdc ciii. Danh gia chat luctng ciii theo cac tieu chudn tren. Ket qua la; Khi nhiel dp say tang, chat luong ciii say giam. Trong khoang nhict dp say 50-60"C, chai lucmg ciii say hdu nhu gid'ng nhau d ca ba chi lieu chat lucmg la trang thai, mdu
sdc va tinh cd the chap nhan dupe va dat sd didm chat lucmg cao nhat. Cha't lupng ciii sau sa'y 1 den ham dm qua 44± 1 % (Long tet) la tdt nhdt khi say d nhiet dp 50-60"C .
3.1.2. Anh hudng ciia ham am qua de boc cui den chat lupng cui sau say 1 (long tet)
Cac mdu chudn bi thi nghiem dupe thuc hien gid'ng nhu muc 3.3.1. Nhan qua dupe say d nhiet dp 60"±l"C tdi cac ham am 37, 40, 45, 50, 55, 60, 65±I%) rdi tien hanh bdc ciii. Danh gia chat luemg ciii theo cac tieu chudn tren. Ket qua la: (That lugng cui sau sdy I 6 nhiet dp say 60"C (Long tet) la tdi nhai khi say den ham am qua dd bdc cui la 40±I%.
3.1.3. Anh hucmg ciia tdc dp bay hoi am den chat lupng cui sau saiy 1 (long tet)
Tdc dp bay hoi am bieu thj dp giam am eua nhan qua (%) theo thdi gian (gid). Cac mdu thf nghiem dupe chudn bj nhu muc 3.1.1. Nhan qua dupe say d eae nhiet dp 50, 60, 70, 80+I"C den ham dm qua la 40, 45, 50, 55, 60, 65±1% d cac td'c dp bay hoi dm khac nhau ma bieu thj gian tiep qua thdi gian say 20, 25, 30, 35, 40, 45h. Ket qua cho thay chat lupng eiii .sau say I d eac nhiet dp say va ham am qua khac nhau (long let) la tdt nhdt khi say vdi tdc dp bay hoi am la 0,92-1,15%/h.
3.1.4. Anh hudmg cua cac chat xir ly den chat lupng cui sau saiy 2 (long tet)
Nhan qua dupe chudn bj nhu muc 3.3.1. Nhan sau say 1 (nhiet dp say; 60"C, ham dm qua de bdc ciii: 40%, tdc do bay hoi am; 1,02%/h) dupe dem di bdc ciii. Sir dung cui bdc dupe dem tien hanh xir ly nhu sau rdi dem di .say 2. « . ' ! j *
Cdch tien hanh xif ly: . •' :-. ,i;
Nhiing ciii trong dung djch Na,HS04 Ig/I; 2g/l; 3g/I trong 3 phut, de rao rdi dem sdy 2.
XPng ciii bdng hoi SO, (Ig; 2g; 3g S) trong 40 phut rdi dem say 2.
Rira ciii bang nudc 100"C; 50"C; nudc thudng trong 2-3 phiit, de rao rdi dem say 2.
.Say 2 dupe tidn hanh d nhiet dp 60"C trong thdi gian dii dd de'n khd, cdng doan say 2 dua trcn ket qua say 1 ve cac thdng sd nhiet dp va chai lucmg long tet chii ydu phu thupc quyet djnh viio say I nen say 2 chi dieu chinh et nhiet dc) say nay la cd kha nang bay hcti dm cho de'n khd.
Kcl qua cho thay chat lupng ciii sau say 2 lii tdt nhai khi ciii nhan sau say 1 ductc xir ly bdng each xdng ciii bang hoi SO, (2g S/0,352m-') trong 40 phiit rdi dem say 2.
3.1.5. Cdng nghe say long tet
Tir cac kdl qua nghien curu anh huetng ciia nhiet dp say (±1"C), ham dm qua klii bdc ciii (±1%) va tetc dp bay heti dm (ii),0/%>am/h) trong qua trinh say ddn chdt lupng long let. Di tai da xac djnh dupe dudng cong say va dudng cong nhiel dp say nhu sau (hinh I va 2):
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Ilinh 1. Duemg cong say long let Hinh 2. Quan he giua nhiet do va thai gian say long let
3-2. Long xoay
Long xoay dupe tao thanh bdi; Nhan qua dupe tach vd va hot ngay liic cdn tuoi, lay ciii dem say de'n khP.
Nhan qua
Ciii
••Tach vd va bpt i ^ Say 1
i
Sa'y2 •Long xoayVd va bpt
3.2.1. Anh hudng cua nhiet dp say 1 den chat lupng ciii say sau say 1 (long xoay) Chai lupng ciii say sau sayl dupe bieu thj chu yeu (tinh theo thir tu uu tien) la;
- Trang thdi: Tir ciii nguyen den ciii nat irng vdi sd diem tir 5 den I.
- Hinh ddng: Tir niim qua co lai nguyen hinh cau (Hinh qua nhan tu nhien) den niim qua md khdng eo lai thanh hinh cdu iing vcii sd diem la tir 5 de'n 1.
- Mdu sdc: Tir mdu trdng tu nhien ciia cdi tuoi de'n mau vang sang khdng cd ddm chay mdu nau ung vcii so diem tii 5 den I.
Nhan qua dupe phan loai, loai bd cudng, la, lam sach, rdi tien hanh bdc vd ddng thdi vdi tach bat ngay. Cui dupe giu nguyen hinh dupe xdp vao khay say (khay say dupe rira sach, de khP, rdi dui>e bPi iron mpt Idp dau an de chdng dinh khay sau nay). Dua ca khay say da xep ciii vao may sa'y dd say.
Say dupe tien hanh d cac nhiet dp say 70, 80, 90, 100, 110, 120, 130, 140, 150±rC ung vdi eac thdi gian khac nhau dd sao cho ham dm ciia cui sau say 1 la 70±1%. Kdt qua dupe chi ra d cae hinh 3.
Tir cae ket qua tren cho tha'y rdng chai lupng ciii sau say 1 (long xoay) d ham dm 70±1% la tdt nhat khi ciii nhan dupe say d nhiet dp I20-130±1"C.
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Hinh 3. Anh hircjng cua nhiet dp say 1 den chai liremg ciii sau sayl (Long xoay)
3.2.2. Anh hucmg ciia ham aim ciii sau say 1 den chat lupng cui (long xoay)
Chudn bj mdu thi nghiem nhu muc 3.2.1. Ciii nhan dupe dem di say den cac ham am 65, 70, 75±1% d nhiet dp .say I20±rC. Kdt qua dupe chi ra d cac hinh 4.
Tir cac kei qua tren cho thay rdng chat lupng ciii sau say 1 (long xoay) d nhiet dp I20±l C la tdt nhai khi ciii nhan cd gia trj ham dm la 70±1 %.
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Hinh 4. Anh hircmg ciia ham am ciii den chai liremg ciii sau sayl or nhiet do say UQfC (long xoay)
3.2.3. Anh hudmg ciia tdc dp bay hoi am khi sayl den chat lucmg cui nhan sau saiy 1 (long xoay) Tdc dp bay hoi dm bieu thj dp giam dm ciia ciii nhan (%) theo thdi gian (gid). Cac mdu thi nghiem dupe chuan bj nhu muc 3.2.1. Ciii nhan dupe sdy d cac nhiet dp 70, 90, 110, 130, 150±I"C den ham am qua la 70±1% d cac td'c dp bay hoi dm khac nhau ma bidu thj gian tie'p qua thdi gian say 60, 50, 40, 30, 20 phut tuong ung. Kei qua chi ra d cac hinh 5.
Til cac ket qua tren cho thay rdng chai lupng ciii sau say 1 d cac nhiet dp sa'y va ham am qua khac nhau (long xoay) la tdt nhai khi say vdi td'c dp bay hoi dm la 32%/b.
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Hinh 5. Anh hirctng ciia ham am ciii den chai lucmg ciii sau saiyl o nhiet do say 120"C (long xoay)
3.2.4. Anh hudng ciia nhict dp .say 2 den chat luong ciii sau say 2 (long xoay)
Ciii ,sau say 1 (d nhicit dp say 120±rC trong thdi gian 35 phiit den ham dm ciii 70+1%) dupe tidp tuc say 2 d cac nhiel dp say 50, 55, 60, 65, 70, 75, 80±1"C de'n khP (ham dm cudi ciing cua CLU sau say 2 la 35-38%). Ket qua dupe chi ra d cac hinh 9 va 10.
Tit cac ket qua tren cho thay rdng chat lupng ciii sau say 2 (long xoay) d nhiet dp say 2 la 50- 60±1"C la tdt nhai.
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i i " ' ^ j r Hinh 6. Anh hircmg ciia nhiel do say 2 den chi lieu chat lucmg mau sac ciii sau say 2 (long xoay)
3.2.5. Anh hucmg ciia tdc dp bay hoi dm khi say 2 den chat lupng ciii sau say 2 (long xoay) Tdc dp bay hoi am bieu thj dp giam dm ciia ciii nhan (%) theo thdi gian (gid). Cac mdu thi nghiem dupe chudn bj nhu muc 3.2.4. Ciii nhan dupe say d cac nhiet dp 50, 55, 60, 65, 70, 75,
oO_l C de'n ham am ciii la 35-38% d cac td'c dp bay hoi am khac nhau ma bieu thj gian tie'p qua tbdi gian say tuong ung la 13, 12, 11, 10, 9, 8, 7 h. Kei q u i chi ra d hinh 7.
Ket qua hinh chi ra rdng: trong khoang td'c dp bay hoi dm 2,69-3,18% dm/h thi chai lupng cui nhan la cao nhat ca d 3 chi lieu. Neu tdc dp bay hoi dm tang dan d gia trj ldn hon 3,18% dm/h thi chai luctng ciii nhan d chi tieu hinh dang, trang thai van giir nguyen nhung giam manh d chi tieu mau sdc xudng didm thap nhai (1/5 diem d td'c dp bay hoi dm 5,0% am/h).
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Hinh 7. Anh hircJng cua loc do bay hoi am khi say 2 den chai liremg ciii
3.2.6. Cdng nghe say long nhan xoay
Tir cac ket qua nghien cuu anh huetng ciia nhiet dp say (±1"C), ham dm ciii sau .say 1 (±1%0 va tdc dp bay hoi am (±0,01%dm/h) trong qua trinh say de'n chai lupng long xoay. De lai da xac djnh dupe dudng cong say va dudng bidu dien quan he nhiet dp say theo thdi gian, qui trinh say long nhan xctay va chai lupng san pham nhu hinh 8 va 9.
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Hinh 8. Duimg cong say long nhan xoay
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Hinh 9. Duimg cong nhiel dt) say long nhan xoay
Chai lupng cam quan san phdm long nhan xoay Hinh ddng: Trdn dep ddu gidng nhu hat sen Mdu sdc: Vang sang trong sang trdng trong
Trang thdi: Cung hi mat, deo loan khdi, khd hat khdng dinh ldn nhau Mid vi: Thom ngon dac trimg eiia nhan, vj ngpt sdc
Tinh hdp ddn sdn phdm: 10/10 (diem tuyet ddi)
Tinh cd the chdp nhdn dugc: 11/10 (cact hon diem tuyet ddi. rai thich) Ham dm: 36-38%
Ham lupng dudng: 55-60%
• 1 ' - I ' • ;
Thuyet minh qui trinh:
1. Nhan qua: Nhan nguyen lieu say la nhan tuoi thu hoach tir cac vudn nhan hoac thu mua ngoai chp dp chin binh thudng nhu nhan an tuoi. Cd the sir dung cac qua rung cudng hoac xdu ma nhung chat lupng vdn cdn lot de ha gia thanh san pham.
2. Lua chpn: Ddu tien la loai bd eae qua bj sau, thdi hdng hoac eac qua cd dp chin khPng hpp ly. Sau dd loai bo cudng, la va lam sach. TrUdng hpp ed ddi hdi eao vd chat lupng long nhan thi cdn phan loai theo kich thudc va trpng lupng qua dam bao qua trinh say dupe ddng ddu vd cac thdng sd ky thuat tao san phdm tdt hon.
3. Bdc vd, xoay hat: Tie'n hanh bdc vd va xoay bat bdng cae dung cu chuyen diing. Vdi dung cu hinh dng. ta cdm ddu dng kim loai cua dng xoay thdng vao qua nhan, lay diem cudng ciia qua nhan lam tam, xoay nhe khoang I vdng cho ddu dng xuyen qua phdn vd va phdn ciii cua qua nhan cdm vao hat nhan rdi Idi hat nhan ra khdi ciii eiia nd, ,sau dd nhi: nhangbdc vd nhan ra khdi ciii. Ddi vdi dung cu binh ngdi but, ta lay ddu nhpn ciia dung cu tach mpt it vd d cudng ciia qua nhan, sau dd cdm ddu nhpn dd xuyen qua eiii nhan, sau de'n khoang 1/3 hat nhan rdi xoay trdn xung quanh hat nhan cho den khi hat nhan tach khdi ciii nhan thi mdc hat nhan ra khdi ciii va Ipt bd vd nhan .Sau khi xoay hat va bdc vd, ciii nhan dupe xep ngay vao khay say. Hien nay, dung cu hinh ngdi but phd bie'n hon.
4. Xep vao khay say: Khay say dupe lam tir cac vat lieu nhu tre; nii-a. Trude khi xep nhan vao khay say, nen quel mpt leip ddu an mdng vao day khay cho khdi dinh. Chi xep mpt Icip ciii tren khay, khoang each gitra cae ciii khPng qua day. Didu can luu y khi xdp ciii nhan vao khay say la dat ciii nhan dung theo chidu mieng ciii (niim qua) ngira len tren.
5. Dua khay vao may say: Khi nhiet dp may say dat dupe khoang 130"C mdi dua cac khay nhan vao may say. Ndn dua cac khay say vao may mpt each Idn lugt va tranh dua ddng loat tai ca cac khay say vao mpt liic se lam nhiet dp may say ha xudng va khdng dat duetc muc yeu cAu. Khi dua khay vao may say can thao tiic nhanh vl ndu ciia may say md lau se lam giam nhiet dp budng say.
6. Say 1: Sau cdng doan dua khay viio may say la bdt ddu giai doan say 1. Say 1 ddng vai trd quyet dinh ddi vdi chat lupng ciia san phdm long nhan. Neu thuc hien tdt giai doan say nay thi san phdm long nhan mdi cd hinh dang va mau sdc dep. Sa'y I d nhiet dp 120- 130±r'C keo dai khoang 30-35 phut, tuy theo dp dm ban ddu ciia ciii nhan, sao eho dp dm cua ctii nhan sau say 1 la 70±1%. Trong qua trinh say cd thd tidn hanh kiem tra ham am cua ciu nhan bdng each can khdi lupng ban ddu cua eiii nhan dem say va khdi lupng ciia ciii nhan khi dang say. Cdn dam bao nhiet dp say I20-I30"C sudt qua trinh say I.
7. Dao: De ciii nhan dupe khP ddu, cdn dao nhan bdng each thay ddi vj tri ciia cac khay nguyen liciu trong may say. Cd the ddi vj tri eiia cac khay cdn udt nhidu hon cho cac khay da khd nhieu hon va ddi vdi timg khay thi quay phia nhan da khd nhidu hon vd phia gdn true may say, phia nhan eon udt nhidu vd phia gdn thanh budng say.
8. Say 2: Say 2 dupe bdt dau ngay sau sdy 1 bdng each giam ddn nhiet dp ciia may say xudng khoang 50-60"C. Duy tri nhiet dp nay cho de'n khi ket thuc qua trinh say. Qua trinh say 2 dupe lien hanh ket hpp vdi thao tac dao. Qua trinh say nay kdt thue khi ham am cLia nhan khoang 35-38% rdi tidn hanh ii ngay trong may say hoac ben ngoai may bang each phii leip vai day tren timg khay nhan trong 10-15 phut.
9. Phan loai long
Tie'n banh phan loai long nhan thanh loai 1,2,3.... tuy theo chai lupng ciia long nhan 10. Dung goi, bao quan
Long nhan da kbP dupe ddng gdi bang bao PE, PVC theo timg loai rieng nhu da phan loai d tren, bao quan noi khd mat trong 12 thang.
3.2.7. Qui trinh cong nghe say long nhan xoay
Bdi tron khay
Lua chon
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Bdc vd, xoay hat
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Xep vao khay
Vd, hat
Dua vao may say
m-
Say 1 (120-130-C)
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Dao khay
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Say 2 (50-60-C)
Dao khay
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U de'n khd
Fhan loai long
Ddng gdi
3.3. May say long nhan true dung quay Sn-300 3.3.1. Cau tao may say: Gdm 3 phdn chinh (hinh 10)
Quat gid
Bep than
Hinh 10. Set dd may say SH 300
a) Budng sdy •^.
Budng say: la mett budng hinh tru dueing kinh 742 mm, chieu cao 850 mm. Tai vj tri tam mat due'ti va tren budng say duetc cd djnh 2 d dd true nhd 6 thanh dd tir diem chu vi ngoai vao tam theo dudng kinh, bao che theo loan bp chu vi bdng tPn 1 mm hoac inox 0,8 mm, trong dd mdt nira ban nguyet theo chu vi lit cd dinh dd gitr dinh vi hai mat tren va dudi, nira ban nguyet cdn lai la cira budng say dupe ddng md bang ban Id. Phia tren budng say cd ndp day bdng dupe khoet 8 cira hinh thang nhd de thoat khdng khi dm thai ra ngoai.
True: Gitra tam budng say la mpt true dudng ki'nh 35 mm, chidu dai 1130 mm dupe ldp thdng dung viio 2 d dd true tren. Doc chieu dung ciia true dupe Idp 8 tdng gia dd khay say dudng kinh 738 mm, each diu nhau theo chidu dai true, mdi tdng gia dd la 2 nira dupe bdt dm vao true bang bu long de cd thd thao ldp hoac djch chuyen dp cao cac tdng khay sdy. Ddu true dudi ductc lap 1 canh quat hudng true dudng kinh 350 mm dd tao phan gid ddu trong budng say va cd thd nhd nd ma true cd the quay dupe dd dang khi cd ddng khi ndng dupe thdi vao budng say. Dau true tren dupe Idp mpt can quay tay dd cd thd quay true dupe bdng tay trong qua trinh say. Nhd true quay dupe ma gid ndng cd thd dao trpn ddu d trong budng say, nguyen lieu sdy cd the dupe djch chuyen tir vi tri nay sang vj tri khae nhung vdn gitr dupe nguyen hinh cua nguyen lieu vi khong cdn dpng chain den nguyen lieu.
Khay say: Khay say hinb ban nguyet (Nira hinh trdn). dudng kinh 738 mm. giira tam khay cung dupe lam khuyet 1dm dudng kinh 40 mm dd ldp vao khdi vuiing true, thanh khay cao 2 cm bang inox, day khay bdng ludi nhdm dpt IP hinh thoi 2 x3 mm, phia dudi cd nep dd dc khdi vdng khay. Ciir 2 khay dupe dat tren mpt tang gia dd khay, tren cac tang khay dupe xep so le nhau de triet tieu dupe cac khe hd ciia cac lang khay. Trong trudng hgp say dac biet cd the xep khay theo each rieng de tang hieu qua say.
b) Gid da budng sdy
Gia dd budng say la mpt hinh tru dudng kinh 745 mm, chieu cao 680 mm. Hinh tru nay duetc ban voi hinh chdp cut dudng kinh ldn bdng dudng kinh hinh Iru tren, dudng kinh nhd 340 mm, chieu cao hinh chdp 290 mm, dudng kinh nhd chinh la cira khdng khi ndng vao budng say. Tai cira nay dupe ndi vdi cira ra ciia caloriphe. Tai bd mat hinh chdp cut dupe ndi 3 chan dd each ddu theo chu vi dat diing loan bp gia dd dd. Do cao ciia chan dd cd the thay ddi dd sao cho cira khdng khi ndng vao budng say each mat dai diing bdng dp cao cua bep than.
c) Cum cap nhiet
Caloriphe: Gdm 60 dng thep dudng kinh 14 mm, chieu day thanh dng 0,5 mm, chieu dai 1500 mm dupe xdp dpc theo chidu dai bdi hai mat bich long dng, phia dudi cd hai chan dd cd dp cao bdng diing bdp than. Toan bp cac dng dupe bao che bang tPn 1 mm de khdi tdn thai nhicit.
Ciia ra eiia caloriphe dupe lap vao cira vao ciia gia dd (dudng kinh nho ciia hinh chdp cut), Cira vao cua caloriphe dupe lap vdi cira ra ciia quat li tam.
Quat li tam: Quat dupe mua sdn dd lap viio hci thd'ng nay.
Luu lupng: 150-200m3/h Ap sudt; 20-25 mmHg
Cira ra ciia quat dupe ldp vdi cira viio ciia caloriphe
Bep than: Cd the sir dung bdp than td ong, bep than da (Kip le). hoac bdp than bun dang cd san trcn thi truetng deu ductc
3.3.2. Nguyen iy lam vice
Tuy thupc viio hinh thire su dung thuc tc ciia noi sir dung ma may say cd ihc vira lam vi(jc gian doan theo me (nguyen lii^u vao va ra hdt mpt lan) va vira cd the lam vice lien luc (mpt hoac vai khay da kho say xong cd the bd ra \a cho mdt hoac vai khay nguyen lieu ue'tt viio say ticp \a cir nhu the mai mai cho tdi khi bet nguyiin lieu thi ihdi).
Nguyen lieu dupe xep vao khay rdi dat vao gia dd khay trong budng say. Khi xep hdt tat ca sd luc;mg cac khay thi ddng cira budng say va bdt dau bat quat. khdng khi dupe lam ndng bdi caloriphe di vao budng say, tie'p xiic vdi vat lieu say, mang dm thai ra ngoiii budng say \'a qua trinh say bdt dau. Trong qua trinh say. nhd luong gid ndng thdi vao budng say cung \di canh quat ldp d ddu true dudi va ca dudi tac dpng quay tay, true duetc quay, khi true quay thi tat ca ciic khay treo tren true cung deiu quay trdn xung quanh true tao la su chuyen vi tri cua nguycin lieu trong budng say, tang su ddng ddu tidp xuc cua nguyen lieu vdi tac nhan say. Hem ntra, khi true quay, cae khay treo tren true cung ddu quay tao ra sir va chain manh giOra khay say, nguyen lieu say vdi tac nhan .say (khdng khi ndng) nhdm dao gid ndng deu dan trong toiin the tich budng say de cd nhiet dp say ddng ddu tai cac vj tri khac nhau trong loan bp budng say.
Sau mpt thdi gian nhat dinh (2-3 gid/lan) cac khay say duetc dao v; tri trcn cac tang khay nhdm tang them su ddng ddu mpt lan niia (ddi vdi say gian doan ihco mc:). Hoac sau mot thdi gian nhai djnh (8 gid ddu tien vii ve sau cu 2-3 gid/lan) nguyen liilu injn ca.. khay say da kho co
thd bd ra ket thiic qua trinh say, ddn eac khay khae xudng phia dudi, bd them khay nguyen lieu mdi vao tren (ddi vdi say lien luc) va tiep tuc nhu the mat mai cho tdi khi het nguyen lieu thi thdi,
liic dd lap lai theo kidu say gian detan (cho me nguyen lic:u cudi ciing).
Dieu chinh nhict dp tac nhan say, nhiel dp say theo yeu cau cPng nghe bdng didu chinh mure dp chay cua bdp than.
Cac chi tieu ky thuat ciia may say:
• Nang suai; 70 kg nhan tuoi/me 12-20 gid/1 may (Say gian doan)
250-300 kg nhan tueti/ngay/2 may (Say lien tuc) _^^
• Tieu tiin than; 1 -2 vien than Id ong/h (Loai than 1,5 kg/vien) hoac 2-3 kg than biin/h
• Tieu tdn dicjn; 90W/h • li :U<i:[i.}y^
• Lao dpng van hanh; 1 ngudi
• Kich thuetc (phdn budng say vii gia dd); Dudng kinh; 745 mm, Chidu eao: 1530 mm
• Khdi luetng tctiin bp: 98 kg (Bao gdm budng say, gia dd, caloriphe) Ket qua md hinh thii nghiem say nhan:
Sdy thu nghiem tqi Vien Cdng nghe sau thu hoach (Thdng 7/2000):
.Say loai Ictng xoay; ••
Nang suai: 65 kg nhan tueti/nic (.Say gian doan) ; -..
Nhict dp say; 120-60"C Thdi gian say; 12 h
Dd dm CLii ban dau; 86%
Do am long nhan sau say: 'M% :,, ;. =' Khcii luctng long nhan sau say: 6,8 kg
Chai luemg san pham: elco. mau vang canh diin sang trong. miii thetm ciia nhan. vj ngon dac trung.
Sdy trinh dien ten Thon Phifong Thong, Xd Phuong Chieu, Huyen 'Tien lu, Tinh Hung Yen (Thdng 8/2000) ^ ,
Say letai long xctay:
Nang suai; 70 kg/mc
Nhict dp say; 120-60"C ^ ' Dp am cLii ban dau; 85-86%
Dp dm long nhan sau say: 35-37%' Khcii lupng lemg nhan sau say: 7,3 kg
Chai luetng san phdm: hinh dang trdn dc^p (gidng hinh hat sen), mau vang nhat sang trang, be mat hat cumg hon, cac hat khdng dinh vao nhau, miii vj thom ngon dac trung ciia nhiin.
IV. KETLU.VN
May say long nhan xctay ban co gidi ,SN 300 lam vicjc theo nguyen ly say ddi luu dang true dung quay, sir dung khdng khi ncing ihay cho khdi Id, dao bdng true quay tay thay cho phai md cira budng say dc dact bdng lay lien tuc se khdc phuc dupe cac nhuetc diem ciia Id say thii cdng la chai luoiig long xoay sach bao dam vc; sinh an loiin thuc phdm, dd didu ehinh va kidm soat cac Ihdng sd say, tiet kicm nhiet va dn dinh nhict khi say do khdng phai md cira de dao va giam thidu P nlncm nini trucing do khoi, bui vii nhict ndng gay ra. Giiii phong dupe nhidu sue lao dcing, van hanh dc \it nhiin hctn loai bd vai va, nang nhpc khi van hiinh say. May duetc thicl ke sir dung mdt
qu^t dien 90W, dot bdng be'p than id ong hoac than biin 2-3kg/h, nang suai say 70 kg nhan qua/me theo cac thdng sd sau day:
Vdi long tet: ed hai qua trinh say. Say 1 d nhiet dp 60"C tdi ham am qua de bdc vd va hat la 40% vdi tdc dp bdc hoi dm la 1,02%/h, sau dd dem ciii sau say 1 di sdng hoi luu huynh lieu lupng 2 gam/0,353m^ trong 40 phut rdi lien hanh say 2 cung d 60"C cho de'n khd (35- 37%) se ed long tet chat lupng tPi nhai.
Vcii long xoay; Cung cd hai qua trinh say. Say I d nhiet dp 120C, say de'n ham am ctii 70% (trong khoang 30-35 phut) rdi chuydn sang say 2 d 50-60"C cho de'n khd (35-37%) vcii td'c dp bdc hoi dm la 32% am/h (ddi vdi say 1) va 2,69-3,18% am/h (ddi vdi say 2) se eho chat lucpng long nhan xoay tdi nhai.
- Chai lupng long nhan xoay dat dupe dep ve trang thai, hinh dang, mau sdc va huong vi se ed gia ban cao hon nhidu so vdi long tet (gap 3-4 Idn).
TAI LIEU THAM KHAO
1. Hoang Van Chudc. Ky thuat say- Nha xuai ban khoa hpc ky thuat 1997.
2. Cao Van Hting va cpng su. Cac ye'u td anh hudng den td'c dp bay hoi dm trong qua trinh sa'y thdc gid'ng bdng may sa'y SH 1-200 - Ndng nghiep va Cdng nghiep thuc phdm, 8-2000 3. Bp Nong nghiep va PTNT. Hpi nghj so kei va trinh didn may say liia khu vuc ddng bdng
sdng Cim long - TP Hd Chi Minh, 9-2000.
4. Bp NPng nghiep va PTN. Tai lieu tap huan may say hat - Ha Npi 2000.
5. Wallace B. Van Arsdel, Michael J. Copley, Arthur I. Morgan, Jr Food dehydration - The AVI Publishing Company, INC, 1973.
6. Bp NPng nghiep va PTNT. Bao cao tinh hinh san xuai va lieu thu nhan-Ha Npi. 7-2000.
7. B.R Champ, E.Highley and G.J.Johnson. Grain drying in Asia - ACIAR proceedings No 71. 1996.
STUDY ON ESTABLISHMENT OF TECHNOLOGY AND EQUIMENT FOR LONGAN DRYING
Cao Van Hiing, Dang Xuan Mai, Biii Kim Khanh, Nguyin Thi Tii Quynh, Nguyen Thj Thu Trang, Dang Thj Thanh Quyen
Division of Food Preservation - PHTI
Semi-mechanical dryer of SN 300 with capacity of 70 kgs longan fmit^atch and 2-3 kgs needed eoal/h is made appropriately to household scale. Through the drying experiments, we can establish the drying process and drying model as followings: For "Long xoay", from initial pulp longan moiture content of 85-86%, heated air provides wide temperature rang of 120-130"C at 30-35 minutes for drying 1 to moiture content of 70% and 50-60"C for drying 2 to final moiture content of 35-31%. As drying as longan mixing-up of 10-15 minutes/time by rotary wheel or hand and take about 32%) moisture content/h (for drying 1) and 2.69-3.18% moisture content/h (for drying 2) to be get highest quality.
In term of "long xoay" quality, sensory evaluations of product are better than that of companson with the control (manual drying). The dryer works effectively for "long xoay" and not for the
"long tet". The dryer is acceptable only as an intermediate technology.
