Technical Service Report

4/15/15

Re:

TSR# 15-035 Boston Sake Fining & Filtration Study

Bench scale fining & filtration studies were completed to determine the best method of achieving either visual clarity
or sterility of a sample from Boston Sake. Results suggest that at a minimum the customer should chill & decant thesake prior to filtration and filter life can be improved further by fining with 10# /1000gal of Vitiben bentonite.
If visual clarity is desired, 10 CSF-XC 40cm filter sheets are recommended to clarify decanted sake while less than 4CSF-XC 40cm filter sheets are recommended to clarify fined & decanted sake. Following CSF-XC filtration, thesample appears visually clear but is not suitable for membrane filtration.
If sterile membrane filtration is desired, 20 CSF-SF 40cm filter sheets are recommended to clarify decanted sakewhile only 7 CSF-SF 40cm filter sheets are recommended to clarify fined & decanted sake. Following CSF-SF
filtration, clogging index results suggest the sake is ready for efficient 0.45µ membrane filtration.
OBJECTIVEThe purpose of this study is to provide recommended fining/filtration options for clarifying sake to achieve visualclarity or sterility.
PROCEDURES
1 gallon of unclarified sake was submitted by Boston Sake for bench scale fining and filtration trials. The customer
ocurrently chills the sake to 2-4 C and is interested in filtering it through either a 5µ nominal filter for visual clarity or a
0.45µ membrane for sterility using their current 40cm filter press.
Unclarified sake was filtered through CSF-XC (5µ nominal) or CSF-SF (0.45µ nominal) in a 2” Posiseal housing at
2228gal/hr/ft or 8gal/hr/ft respectively based on manufacturer recommended flow rates. Pressure was monitored
throughout the filtration and testing was terminated at 21psid based on pump limitations and/or recommended
omaximum pressure. These filtrations were repeated using unclarified sake that had been chilled at 2 C for 24hrs anddecanted to remove precipitate prior to filtration. Results of these filtrations are displayed in Figures 1-2 andsummarized in Table 2.
Fining trials were conducted to determine if fining agents could further clarify the sake before filtration. 200mL ofo
unclarified sake was dosed with either silica hydrogel (Britesorb A100) or Bentonite (Vitiben) and chilled at 2 C for
24hrs before decanting to remove precipitate. Silica hydrogel was dosed at 400, 600 & 800ppm and Bentonite wasdosed at 5, 7 & 10lb/1000gal based on manufacturer recommendations & past sake customer experience. The
turbidity of decanted samples (including an un-fined control) was measured and displayed in Table 1.
10lb/1000gal bentonite fining was identified as the sample providing the best sake clarity, so a larger (2L) sample ofsake was fined, chilled and decanted at this dose rate in preparation for filtration. The sample was filtered throughCSF-XC or CSF-SF in a 2” Posiseal housing as previously described, with results displayed in Figure 3 &summarized in Table 2.
To determine if filtration through CSF-XC or CSF-SF adequately prepared the sake for membrane clarification, aclogging index test was conducted to determine membrane filterability. Fined sake pre-filtered through either CSFXC or CSF-SF was passed through a 0.45µ membrane using 2 bar pressure while recording the time it takes to filter
the first 200mL and 400mL of fluid. The clogging index value is calculated using the formula [T400 (min) – 2 T200(min)] X 100. A value of 0-12 indicates good filterability; 12-25 provides acceptable filterability, and a value greaterthan 25 displays poor filterability. Results are included in Table 3.
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RESULTS AND DATA
Unclarified sake was filtered through CSF-XC & CSF-SF as received or chilled and decanted prior to filtration throughCSF-XC & CSF-SF. Filtration results following each preparation method are displayed in Figures 1-2.
Figure 1: Unclarified Sake Filtration

Figure 2: Decanted Sake Filtration

Sake Filtration (not fined or decanted)

Decanted (not fined) Sake Filtration(Challenge Material = Unfined Sake (307NTU) @ 2 deg C)(Challenge Material = Decanted (not fined) Sake (42.3NTU) @ 2 deg C)

Pressure vs. Throughput

Pressure vs. Throughput

35303025
Pressure (psi)Pressure (psi)2520151020
15105500
0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0

2.0

Throughput (Gal/sqf t)

4.0

6.0

8.0

10.0

Throughput (Gal/sqf t)

CSF-SF W093167 - 8gal/hr/ft2 51.9 LPM/m2 0.283NTU
CSF-XC W102183 - 28gal/hr/ft2 635 LPM/m2 0.425NTU

CSF-SF W093167 - 8gal/hr/ft2 51.9 LPM/m2 0.422NTU
CSF-XC W102183 - 28gal/hr/ft2 635 LPM/m2 2.27NTU

Note: decanted sake reservoir was depleted before reaching terminal CSF-XC pressure – dashed line indicates an extrapolated curve

Unclarified sake plugged both the coarse CSF-XC (5µ) and the fine CSF-SF (0.45µ) filters very quickly. Similar
plugging profiles despite the different porosity of these filters suggests that the primary plugging particulate is >5µ,resulting in surface blinding of both filters.
Chilling & decanting sake prior to filtration significantly improved throughput on both filters, though throughput
remained lower than desired. Filter life differences between grades also suggests decanting removed some of thelarge particulate, allowing smaller particulate to pass through the CSF-XC (resulting in longer filter life but slightly
higher turbidity).
To further improve the clarity of sake before filtration, fining trials were conducted at various dose rates using silica
hydrogel or bentonite. Dose rates and resulting turbidities are displayed below in Table 1.
Table 1: Fined Sake Turbidity

SampleTurbidity (NTU)

Original (not fined or decanted)
Decanted (not fined) control
Silica hydrogel - 400ppm
Silica hydrogel - 600ppm
Silica hydrogel - 800ppm
Bentonite - 5 #/1000gal
Bentonite - 7 #/1000gal
Bentonite - 10 #/1000gal

309
36.5
36.3
33.3
32.8
13.7
10.7
8.56

Results suggest that chilling and decanting sake significantly reduced turbidity (309NTU reduced to 36.5NTU), but
addition of silica hydrogel, even up to 800ppm, did very little to reduce turbidity further. However, bentonite
successfully reduced turbidity at 5-10 #/1000gal dosing (13.7-8.5NTU).
Since 10#/1000gal of bentonite provided the best sake clarity, additional sake was dosed at this rate before filtering
through CSF-XC & CSF-SF. Results of fined sake filtrations are displayed below in Figure 3 and a comparison of all
filtrations is summarized in Table 2.

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Figure 3: Fined Sake Filtration
Fined (10# vitiben/1000gal) Sake(Challenge Material = fined (10#Vitiben/1000gal) Sake (8.65NTU) @ 2deg C)

Pressure vs. Throughput

30

Pressure (psi)252015
1050
0.0

5.0

10.0

15.0

20.0

25.0

Throughput (Gal/sqf t)
CSF-SF W093167 - 8gal/hr/ft2 51.9 LPM/m2 0.236NTU
CSF-XC W102183 - 28gal/hr/ft2 635 LPM/m2 2.12NTU

Note: fined sake reservoir was depleted before reaching terminal CSF-XC pressure – could not extrapolate curve because plugging didn’t occur
Table 2: Filtration SummarySample PrepFilterMedia

None
None
Chilled/Decanted
Chilled/Decanted
Fined/Chilled/Decanted
Fined/Chilled/Decanted

CSF-XCCSF-SF
CSF-XCCSF-SF
CSF-XCCSF-SF

Filtration Results
Filtrate
Throughput
Turbidity@ ∆21psi
2(NTU)(gal/ft )
0.4
2.5^
0.3
2.5
0.4
~8.3*^
2.3
4.1
0.2>20.5*^
2.1
11.6Production Needs (assuming 500L batch)Media Area2(ft )# of 40cm sheet
2needed (1.6ft /sheet)

52.8
52.8~15.9
32.2
<6.4
11.4

33
33~1020<47* Note: chilled/decanted throughput estimated by extrapolating plugging curve, fined/chilled/decanted throughput will be significantly greater than
20.5gal/ft2 but could not be extrapolated since plugging did not occur^Note: CSF-XC samples were terminated at ∆21psi due to pump limitations, but manufacturer recommends max ∆ 45psi for this grade makingexpected throughputs slightly higher than reported

Filter life of both CSF-XC & CSF-SF was significantly improved by fining the sake with bentonite prior to filtration. Inthe customer’s 500L batch production process only <4 or 7 filter sheets would be needed to filter through CSF-XC orCSF-SF respectively after fining.
To determine if the sake was suitable for sterile membrane filtration following CSF-XC or CSF-SF pre-filtration, filtrate
was passed through a sterile membrane according to Clogging Index test procedures. Results are displayed below
in Table 3.
Table 3: Clogging Index Results

SampleClogging Index

Fined & CSF-XC filtered Sake
Fined & CSF-SF filtered Sake

Plugged prematurely
3.4

Membrane Filterability
RatingExtremely Poor filterability
Good Filterability (<12)

Results confirm that pre-filtration through CSF-XC (normally used for coarse filtrations) does not provide sufficient
protection for a downstream sterile membrane, plugging prematurely before the test reached completion. However,pre-filtration through CSF-SF successfully prepared the sake for membrane filtration, providing “good” filterability for
efficient use of the sterile membrane.
CONCLUSIONS
Bench scale fining & filtration studies were completed to determine the best method of achieving either visual clarity
or sterility of a sample from Boston Sake. Results suggest that at a minimum the customer should chill & decant thesake prior to filtration and filter life can be improved further by fining with 10# /1000gal of Vitiben bentonite.
If visual clarity is desired, 10 CSF-XC 40cm filter sheets are recommended to clarify decanted sake while less than 4CSF-XC 40cm filter sheets are recommended to clarify fined & decanted sake. Following CSF-XC filtration, thesample appears visually clear but is not suitable for membrane filtration.
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If sterile membrane filtration is desired, 20 CSF-SF 40cm filter sheets are recommended to clarify decanted sakewhile only 7 CSF-SF 40cm filter sheets are recommended to clarify fined & decanted sake. Following CSF-SF
filtration, clogging index results suggest the sake is ready for efficient 0.45µ membrane filtration.
If you have any questions, please contact us.

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