Tomato products: pulp, ketchup, and chili sauce.

Chapter II: Part 2

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================================================================== Sample No.| Ratio of |Insoluble | Sugar | Acid in | Ratio | | pulp | solids | in | solids | of acid | |solids to | in total | solids | of | to | | filtrate | solids | of | liquor | sugar | | solids | | liquor | | | +----------+----------+----------+----------+----------+---------+ | |_Per cent_|_Per cent_|_Per cent_| | 1470 | 1.241 | | 53.5 | 7.6 | 7.0 | 1471 | 1.233 | | 53.2 | 7.7 | 6.9 | 1470-1 | 1.203 | | | | | 1470-2 | 1.203 | | | | | 1470-3 | 1.201 | | | | | | | | | | | 1470-4 | 1.197 | | | | | 1471-1 | 1.184 | | | | | 1471-2 | 1.184 | | | | | 1471-3 | 1.218 | | | | | 1471-4 | 1.203 | | | | | | | | | | | 1572 | 1.109 | | | | | 1573 | 1.117 | 12.8 | | | | 1574 | 1.109 | 11.4 | | | | 1575 | 1.175 | 13.3 | | | | 1662(b) | 1.042 | 3.7 | | | | | | | | | | 1664(c) | 1.040 | 4.7 | | | | 1665 | 1.123 | 14.3 | | | | 701 | 1.140 | 14.7 | 54.8 | 7.0 | 7.8 | 703(d) | 1.022 | 2.4 | 55.9 | 7.0 | 8.0 | 705 | 1.220 | 18.6 | 50.4 | 6.2 | 8.0 | 706 | 1.145 | 11.7 | 48.3 | 6.3 | 7.6 | +----------+----------+----------+----------+----------+---------+

(a) Determined by drying _in vacuo_ at 70° C.
(b) Unconcentrated tomato juice from peeling table.
(c) No. 1662 concentrated.
(d) Clear liquor separated from unconcentrated pulp on standing.
(e) Expressed as invert.

TABLE 4.—_Comparison of Methods for the Determination and Calculation of Solids in Whole Tomato Pulp_

======================================================== | Solids in liquor from filtered pulp | +-----------+----------------------------------+ |By drying | Calculated from-- | |_in vacuo_+-------------+----------+----------+ Sample | at | Immersion | | | No. | 70° C. |refractometer| Specific |Specific | | | reading |gravity(1)|gravity(2)| --------+----------+-------------+----------+----------+ |_Per cent_| _Per cent_ |_Per cent_|_Per cent_| 1290 | 5.24 | 5.31 | 5.35 | 5.35 | 1291 | 5.71 | 5.67 | 5.78 | 5.80 | 1292 | 4.88 | 4.87 | 4.85 | 4.85 | 1293 | 6.28 | 6.21 | 6.33 | 6.35 | 1294 | 5.82 | 5.79 | 5.87 | 5.89 | | | | | | 1295 | 7.69 | 7.67 | 7.82 | 7.82 | 1296 | 8.05 | 7.88 | ... | ... | 1297 | 10.27 | 10.27 | 10.25 | 10.26 | 1299 | 9.09 | 9.06 | 9.05 | 9.06 | 1300 | 6.88 | 6.91 | 6.98 | 6.99 | | | | | | 1301 | 6.68 | 6.59 | ... | ... | 1302 | 6.61 | 6.64 | 6.73 | 6.74 | 1303 | 7.29 | 7.34 | 7.42 | 7.43 | 1304 | 6.20 | 6.16 | 6.30 | 6.30 | 1305 | 7.98 | 7.98 | ... | ... | | | | | | 1306 | 8.01 | 8.05 | ... | ... | 1307 | 6.97 | 6.96 | 7.08 | 7.08 | 1481 | 9.64 | 9.67 | 9.68 | 9.68 | 1482 | 9.86 | 9.81 | 9.70 | 9.71 | 1483 | 10.19 | 10.21 | 10.15 | 10.14 | | | | | | 1484 | 9.23 | 9.15 | 9.10 | 9.11 | 1485 | 7.73 | 7.64 | 7.63 | 7.64 | 1479 | 8.96 | 9.03 | 8.87 | 8.88 | 1486 | 3.76 | ... | 3.62 | 3.63 | 1491 | 4.40 | 4.44 | 4.30 | 4.32 | | | | | | 1496 | 7.31 | 7.39 | 7.30 | 7.31 | 1515 | 7.61 | 7.70 | 7.60 | 7.61 | 1529 | 4.54 | 4.52 | 4.47 | 4.49 | 1530 | 5.42 | 5.32 | 5.30 | 5.31 | 1531 | 6.27 | 6.25 | 6.27 | 6.28 | 1325 | 6.99 | 7.13 | ... | ... | --------+----------+-------------+----------+----------+

=================================================================== | Solids in whole pulp | +----------+-------------+--------------------------------+ | By | Calculated | Calculated from specific | | drying | from | gravity of-- | |_in vacuo_| immersion +----------+----------+----------+ Sample | at 70° C.|refractometer|Filtered | Whole | Filtered | No. | | reading |liquor[3] | pulp | liquor[4)| --------+----------+-------------+----------+----------+----------+ |_Per cent_| _Per cent_ |_Per cent_|_Per cent_|_Per cent_| 1290 | 5.94 | 5.95 | 6.00 | 5.97 | 5.99 | 1291 | 6.54 | 6.36 | 6.48 | 6.47 | 6.50 | 1292 | 5.50 | 5.47 | 5.44 | 5.52 | 5.43 | 1293 | 7.02 | 6.96 | 7.10 | 6.98 | 7.11 | 1294 | 6.48 | 6.49 | 6.58 | 6.45 | 6.60 | | | | | | | 1295 | 8.67 | 8.59 | 8.77 | 8.63 | 8.76 | 1296 | 9.00 | 8.83 | ... | 9.11 | ... | 1297 | 11.20 | 11.50 | 11.47 | 11.20 | 11.49 | 1299 | 10.07 | 10.15 | 10.14 | 10.02 | 10.15 | 1300 | 7.70 | 7.75 | 7.82 | 7.68 | 7.83 | | | | | | | 1301 | 7.36 | 7.38 | ... | 7.43 | ... | 1302 | 7.45 | 7.44 | 7.54 | 7.40 | 7.55 | 1303 | 8.17 | 8.23 | 8.33 | 8.12 | 8.32 | 1304 | 6.88 | 6.90 | 7.06 | 6.95 | 7.06 | 1305 | 9.03 | 8.94 | ... | 8.88 | ... | | | | | | | 1306 | 8.95 | 9.02 | ... | 8.86 | ... | 1307 | 7.86 | 7.81 | 7.93 | 7.83 | 7.93 | 1481 | 10.82 | 10.83 | 10.84 | 10.80 | 10.84 | 1482 | 10.83 | 10.98 | 10.86 | 10.70 | 10.88 | 1483 | 11.21 | 11.43 | 11.36 | 11.17 | 11.36 | | | | | | | 1484 | 10.27 | 10.25 | 10.19 | 10.17 | 10.20 | 1485 | 8.55 | 8.56 | 8.55 | 8.30 | 8.56 | 1479 | 10.00 | 10.10 | 9.94 | 9.88 | 9.85 | 1486 | 4.34 | ... | 4.05 | 3.90 | 4.07 | 1491 | 4.97 | 4.97 | 4.82 | 4.62 | 4.84 | | | | | | | 1496 | 8.27 | 8.28 | 8.18 | 8.15 | 8.29 | 1515 | 8.56 | 8.63 | 8.52 | 8.40 | 8.52 | 1529 | 5.11 | 5.06 | 5.01 | 4.90 | 5.03 | 1530 | 6.21 | 5.97 | 5.94 | 5.97 | 5.95 | 1531 | 7.17 | 7.01 | 7.04 | 6.92 | 7.03 | 1325 | 7.86 | 7.99 | ... | 7.81 | ... | --------+----------+-------------+----------+----------+----------+

(1) From formula on page 30.
(2) The solution factor of O’Sullivan (J. Chem. Soc., 1876, p. 129)
was employed with slight modification. The formula employed was
1000(_d_ - 1000) / 4.35 = per cent solids. In this formula
_d_ = specific gravity of solution at 20° C.
(3) From formula on page 31.
(4) For these figures the formula of footnote 2 was employed and the
results multiplied by 1.12

TABLE 5.—_Tomato Pulp and Filtered Liquor_

========================================================================
Whole pulp | Filtrate from pulp |
------------------------------+---------------------+---------+--------+
Solids by drying | | Solids by drying |Immersion| |
---------------------+ +---------------------+refract- | |
_In vacuo_| At |Specific|_In vacuo_| At | ometer |Specific|
at 70° C.| atmo- |gravity | at 70° C.| atmo- |reading | gravity|
| spheric | at | | spheric | at | at |
| pressure | 20° C. | | pressure |17.5° C. | 20° C.|
| 100° C.| | | 100° C | | |
----------+----------+--------+----------+----------+---------+--------+
_Per cent_|_Per cent_| |_Per cent_|_Per cent_| | |
3.42 | 3.15 | 1.0150 | 3.05 | 2.71 | 26.9 | 1.0133 |
3.47 | 3.20 | 1.0152 | 3.10 | 2.75 | 27.1 | 1.0136 |
3.53 | 3.25 | 1.0155 | 3.15 | 2.80 | 27.3 | 1.0138 |
3.58 | 3.30 | 1.0157 | 3.20 | 2.85 | 27.5 | 1.0140 |
3.64 | 3.35 | 1.0159 | 3.25 | 2.89 | 27.7 | 1.0142 |
| | | | | | |
3.70 | 3.41 | 1.0161 | 3.30 | 2.93 | 27.9 | 1.0144 |
3.76 | 3.46 | 1.0163 | 3.35 | 2.97 | 28.1 | 1.0146 |
3.81 | 3.51 | 1.0166 | 3.40 | 3.02 | 28.3 | 1.0149 |
3.87 | 3.56 | 1.0168 | 3.45 | 3.07 | 28.6 | 1.0151 |
3.92 | 3.61 | 1.0170 | 3.50 | 3.11 | 28.8 | 1.0153 |
| | | | | | |
3.98 | 3.67 | 1.0172 | 3.55 | 3.15 | 29.0 | 1.0155 |
4.03 | 3.72 | 1.0174 | 3.60 | 3.20 | 29.2 | 1.0157 |
4.09 | 3.77 | 1.0177 | 3.65 | 3.24 | 29.4 | 1.0160 |
4.15 | 3.82 | 1.0179 | 3.70 | 3.28 | 29.6 | 1.0162 |
4.20 | 3.87 | 1.0181 | 3.75 | 3.33 | 29.8 | 1.0164 |
| | | | | | |
4.26 | 3.93 | 1.0183 | 3.80 | 3.38 | 30.0 | 1.0166 |
4.31 | 3.98 | 1.0185 | 3.85 | 3.42 | 30.3 | 1.0168 |
4.37 | 4.03 | 1.0188 | 3.90 | 3.46 | 30.5 | 1.0170 |
4.43 | 4.08 | 1.0190 | 3.95 | 3.51 | 30.7 | 1.0173 |
4.48 | 4.13 | 1.0192 | 4.00 | 3.55 | 30.9 | 1.0175 |
| | | | | | |
4 54 | 4.18 | 1.0194 | 4.05 | 3.60 | 31.1 | 1.0177 |
4.59 | 4.23 | 1.0197 | 4.10 | 3.64 | 31.3 | 1.0179 |
4.65 | 4.28 | 1.0199 | 4.15 | 3.69 | 31.5 | 1.0181 |
4.71 | 4.33 | 1.0201 | 4.20 | 3.73 | 31.7 | 1.0183 |
4.76 | 4.38 | 1.0203 | 4.25 | 3.78 | 31.9 | 1.0185 |
| | | | | | |
4.82 | 4.44 | 1.0205 | 4.30 | 3.82 | 32.1 | 1.0188 |
4.87 | 4.49 | 1.0208 | 4.35 | 3.86 | 32.3 | 1.0190 |
4.93 | 4.54 | 1.0210 | 4.40 | 3.91 | 32.5 | 1.0192 |
4.99 | 4.59 | 1.0212 | 4.45 | 3.95 | 32.7 | 1.0194 |
5.04 | 4.64 | 1.0215 | 4.50 | 4.00 | 32.9 | 1.0196 |
----------+----------+--------+----------+----------+---------+--------+

TABLE 5.—_Tomato Pulp and Filtered Liquor_—Continued

========================================================================
Whole pulp | Filtrate from pulp |
------------------------------+---------------------+---------+--------+
Solids by drying | | Solids by drying |Immersion| |
---------------------+ +---------------------+refract- | |
_In vacuo_| At |Specific|_In vacuo_| At | ometer |Specific|
at 70° C.| atmo- |gravity | at 70° C.| atmo- |reading | gravity|
| spheric | at | | spheric | at | at |
| pressure | 20° C. | | pressure |17.5° C. | 20° C.|
| 100° C.| | | 100° C | | |
----------+----------+--------+----------+----------+---------+--------+
_Per cent_|_Per cent_| |_Per cent_|_Per cent_| | |
5.10 | 4.70 | 1.0217 | 4.55 | 4.04 | 33.1 | 1.0198 |
5.16 | 4.75 | 1.0219 | 4.60 | 4.09 | 33.3 | 1.0200 |
5.21 | 4.80 | 1.0222 | 4.65 | 4.13 | 33.6 | 1.0203 |
5.27 | 4.85 | 1.0224 | 4.70 | 4.18 | 33.8 | 1.0205 |
5.33 | 4.90 | 1.0226 | 4.75 | 4.22 | 34.0 | 1.0207 |
| | | | | | |
5.38 | 4.96 | 1.0228 | 4.80 | 4.26 | 34.2 | 1.0209 |
5.44 | 5.01 | 1.0230 | 4.85 | 4.31 | 34.4 | 1.0211 |
5.49 | 5.06 | 1.0233 | 4.90 | 4.36 | 34.6 | 1.0213 |
5.55 | 5.11 | 1.0235 | 4.95 | 4.40 | 34.8 | 1.0216 |
5.60 | 5.16 | 1.0237 | 5.00 | 4.44 | 35.0 | 1.0218 |
| | | | | | |
5.66 | 5.21 | 1.0240 | 5.05 | 4.49 | 35.2 | 1.0220 |
5.72 | 5.26 | 1.0242 | 5.10 | 4.53 | 35.4 | 1.0223 |
5.77 | 5.31 | 1.0244 | 5.15 | 4.58 | 35.6 | 1.0225 |
5.83 | 5.36 | 1.0247 | 5.20 | 4.62 | 35.8 | 1.0227 |
5.88 | 5.41 | 1.0249 | 5.25 | 4.66 | 36.0 | 1.0229 |
| | | | | | |
5.94 | 5.47 | 1.0251 | 5.30 | 4.71 | 36.2 | 1.0231 |
6.00 | 5.52 | 1.0253 | 5.35 | 4.75 | 36.4 | 1.1333 |
6.05 | 5.57 | 1.0256 | 5.40 | 4.80 | 36.6 | 1.0235 |
6.11 | 5.62 | 1.0258 | 5.45 | 4.84 | 36.8 | 1.0238 |
6.16 | 5.67 | 1.0260 | 5.50 | 4.89 | 37.1 | 1.0240 |
| | | | | | |
6.22 | 5.73 | 1.0263 | 5.55 | 4.93 | 37.3 | 1.0242 |
6.28 | 5.78 | 1.0265 | 5.60 | 4.98 | 37.5 | 1.0244 |
6.33 | 5.83 | 1.0267 | 5.65 | 5.02 | 37.7 | 1.0246 |
6.39 | 5.88 | 1.0270 | 5.70 | 5.06 | 37.9 | 1.0249 |
6.45 | 5.93 | 1.0272 | 5.75 | 5.11 | 38.1 | 1.0251 |
| | | | | | |
6.50 | 5.99 | 1.0274 | 5.80 | 5.15 | 38.3 | 1.0253 |
6.56 | 6.04 | 1.0276 | 5.85 | 5.20 | 38.5 | 1.0255 |
6.61 | 6.09 | 1.0279 | 5.90 | 5.24 | 38.7 | 1.0257 |
6.67 | 6.14 | 1.0281 | 5.95 | 5.29 | 38.9 | 1.0259 |
6.72 | 6.19 | 1.0283 | 6.00 | 5.33 | 39.1 | 1.0261 |
----------+----------+--------+----------+----------+---------+--------+

TABLE 5.—_Tomato Pulp and Filtered Liquor_—Continued

========================================================================
Whole pulp | Filtrate from pulp |
------------------------------+---------------------+---------+--------+
Solids by drying | | Solids by drying |Immersion| |
---------------------+ +---------------------+refract- | |
_In vacuo_| At |Specific|_In vacuo_| At | ometer |Specific|
at 70° C.| atmo- |gravity | at 70° C.| atmo- |reading | gravity|
| spheric | at | | spheric | at | at |
| pressure | 20° C. | | pressure |17.5° C. | 20° C.|
| 100° C.| | | 100° C | | |
----------+----------+--------+----------+----------+---------+--------+
_Per cent_|_Per cent_| |_Per cent_|_Per cent_| | |
6.78 | 6.24 | 1.0285 | 6.05 | 5.38 | 39.3 | 1.0263 |
6.84 | 6.29 | 1.0288 | 6.10 | 5.42 | 39.5 | 1.0266 |
6.89 | 6.35 | 1.0290 | 6.15 | 5.46 | 39.7 | 1.0268 |
6.95 | 6.41 | 1.0292 | 6.20 | 5.51 | 39.9 | 1.0270 |
7.01 | 6.46 | 1.0294 | 6.25 | 5.56 | 40.1 | 1.0272 |
| | | | | | |
7.06 | 6.51 | 1.0297 | 6.30 | 5.60 | 40.3 | 1.0274 |
7.12 | 6.56 | 1.0299 | 6.35 | 5.64 | 40.6 | 1.0277 |
7.17 | 6.61 | 1.0301 | 6.40 | 5.69 | 40.8 | 1.0279 |
7.23 | 6.66 | 1.0304 | 6.45 | 5.73 | 41.0 | 1.0281 |
7.28 | 6.71 | 1.0306 | 6.50 | 5.78 | 41.2 | 1.0283 |
| | | | | | |
7.34 | 6.76 | 1.0308 | 6.55 | 5.82 | 41.4 | 1.0285 |
7.40 | 6.82 | 1.0310 | 6.60 | 5.86 | 41.6 | 1.0287 |
7.45 | 6.87 | 1.0313 | 6.65 | 5.91 | 41.8 | 1.0290 |
7.51 | 6.92 | 1.0315 | 6.70 | 5.95 | 42.0 | 1.0292 |
7.56 | 6.97 | 1.0317 | 6.75 | 6.00 | 42.2 | 1.0294 |
| | | | | | |
7.62 | 7.02 | 1.0320 | 6.80 | 6.04 | 42.4 | 1.0296 |
7.68 | 7.08 | 1.0322 | 6.85 | 6.09 | 42.6 | 1.0298 |
7.74 | 7.13 | 1.0324 | 6.90 | 6.14 | 42.8 | 1.0300 |
7.79 | 7.18 | 1.0326 | 6.95 | 6.18 | 43.1 | 1.0303 |
7.85 | 7.23 | 1.0329 | 7.00 | 6.22 | 43.3 | 1.0305 |
| | | | | | |
7.90 | 7.28 | 1.0331 | 7.05 | 6.26 | 43.5 | 1.0307 |
7.96 | 7.33 | 1.0333 | 7.10 | 6.31 | 43.7 | 1.0309 |
8.02 | 7.38 | 1.0336 | 7.15 | 6.36 | 43.9 | 1.0311 |
8.07 | 7.43 | 1.0338 | 7.20 | 6.40 | 44.1 | 1.0313 |
8.12 | 7.48 | 1.0340 | 7.25 | 6.44 | 44.3 | 1.0315 |
| | | | | | |
8.18 | 7.54 | 1.0342 | 7.30 | 6.48 | 44.5 | 1.0318 |
8.24 | 7.59 | 1.0345 | 7.35 | 6.53 | 44.7 | 1.0320 |
8.30 | 7.64 | 1.0347 | 7.40 | 6.58 | 44.9 | 1.0322 |
8.35 | 7.69 | 1.0349 | 7.45 | 6.62 | 45.1 | 1.0324 |
8.40 | 7.74 | 1.0352 | 7.50 | 6.66 | 45.3 | 1.0326 |
----------+----------+--------+----------+----------+---------+--------+

TABLE 5.—_Tomato Pulp and Filtered Liquor_—Continued

========================================================================
Whole pulp | Filtrate from pulp |
------------------------------+---------------------+---------+--------+
Solids by drying | | Solids by drying |Immersion| |
---------------------+ +---------------------+refract- | |
_In vacuo_| At |Specific|_In vacuo_| At | ometer |Specific|
at 70° C.| atmo- |gravity | at 70° C.| atmo- |reading | gravity|
| spheric | at | | spheric | at | at |
| pressure | 20° C. | | pressure |17.5° C. | 20° C.|
| 100° C.| | | 100° C | | |
----------+----------+--------+----------+----------+---------+--------+
_Per cent_|_Per cent_| |_Per cent_|_Per cent_| | |
8.46 | 7.79 | 1.0354 | 7.55 | 6.71 | 45.5 | 1.0328 |
8.52 | 7.84 | 1.0356 | 7.60 | 6.76 | 45.7 | 1.0331 |
8.57 | 7.89 | 1.0358 | 7.65 | 6.80 | 45.9 | 1.0333 |
8.63 | 7.95 | 1.0361 | 7.70 | 6.84 | 46.2 | 1.0335 |
8.68 | 8.00 | 1.0363 | 7.75 | 6.89 | 46.4 | 1.0337 |
| | | | | | |
8.74 | 8.05 | 1.0365 | 7.80 | 6.93 | 46.6 | 1.0339 |
8.80 | 8.11 | 1.0367 | 7.85 | 6.98 | 46.8 | 1.0341 |
8.86 | 8.16 | 1.0370 | 7.90 | 7.02 | 47.0 | 1.0344 |
8.91 | 8.21 | 1.0372 | 7.95 | 7.07 | 47.2 | 1.0346 |
8.96 | 8.26 | 1.0374 | 8.00 | 7.11 | 47.4 | 1.0348 |
| | | | | | |
9.02 | 8.31 | 1.0377 | 8.05 | 7.16 | 47.6 | 1.0350 |
9.08 | 8.36 | 1.0379 | 8.10 | 7.20 | 47.8 | 1.0352 |
9.14 | 8.41 | 1.0381 | 8.15 | 7.24 | 48.0 | 1.0354 |
9.19 | 8.46 | 1.0383 | 8.20 | 7.28 | 48.2 | 1.0357 |
9.25 | 8.51 | 1.0386 | 8.25 | 7.33 | 48.4 | 1.0359 |
| | | | | | |
9.30 | 8.57 | 1.0388 | 8.30 | 7.38 | 48.6 | 1.0361 |
9.36 | 8.62 | 1.0390 | 8.35 | 7.42 | 48.8 | 1.0363 |
9.42 | 8.67 | 1.0393 | 8.40 | 7.46 | 49.0 | 1.0366 |
9.47 | 8.72 | 1.0395 | 8.45 | 7.51 | 49.2 | 1.0368 |
9.53 | 8.77 | 1.0397 | 8.50 | 7.55 | 49.4 | 1.0370 |
| | | | | | |
9.58 | 8.83 | 1.0400 | 8.55 | 7.60 | 49.6 | 1.0372 |
9.64 | 8.88 | 1.0402 | 8.60 | 7.64 | 49.8 | 1.0374 |
9.70 | 8.93 | 1.0404 | 8.65 | 7.68 | 50.0 | 1.0376 |
9.75 | 8.98 | 1.0406 | 8.70 | 7.73 | 50.2 | 1.0379 |
9.80 | 9.03 | 1.0408 | 8.75 | 7.78 | 50.4 | 1.0381 |
| | | | | | |
9.86 | 9.09 | 1.0410 | 8.80 | 7.82 | 50.7 | 1.0383 |
9.92 | 9.14 | 1.0413 | 8.85 | 7.86 | 50.9 | 1.0385 |
9.97 | 9.19 | 1.0415 | 8.90 | 7.91 | 51.1 | 1.0387 |
10.02 | 9.24 | 1.0417 | 8.95 | 7.95 | 51.3 | 1.0389 |
10.08 | 9.29 | 1.0419 | 9.00 | 8.00 | 51.5 | 1.0392 |
----------+----------+--------+----------+----------+---------+--------+

TABLE 5.—_Tomato Pulp and Filtered Liquor_—Continued

========================================================================
Whole pulp | Filtrate from pulp |
------------------------------+---------------------+---------+--------+
Solids by drying | | Solids by drying |Immersion| |
---------------------+ +---------------------+refract- | |
_In vacuo_| At |Specific|_In vacuo_| At | ometer |Specific|
at 70° C.| atmo- |gravity | at 70° C.| atmo- |reading | gravity|
| spheric | at | | spheric | at | at |
| pressure | 20° C. | | pressure |17.5° C. | 20° C.|
| 100° C.| | | 100° C | | |
----------+----------+--------+----------+----------+---------+--------+
_Per cent_|_Per cent_| |_Per cent_|_Per cent_| | |
10.14 | 9.35 | 1.0421 | 9.05 | 8.05 | 51.7 | 1.0394 |
10.19 | 9.40 | 1.0424 | 9.10 | 8.09 | 51.9 | 1.0396 |
10.25 | 9.45 | 1.0426 | 9.15 | 8.13 | 52.1 | 1.0398 |
10.30 | 9.50 | 1.0428 | 9.20 | 8.18 | 52.3 | 1.0400 |
10.35 | 9.55 | 1.0430 | 9.25 | 8.22 | 52.5 | 1.0402 |
| | | | | | |
10.41 | 9.60 | 1.0433 | 9.30 | 8.27 | 52.7 | 1.0404 |
10.47 | 9.65 | 1.0435 | 9.35 | 8.31 | 52.9 | 1.0406 |
10.52 | 9.70 | 1.0437 | 9.40 | 8.35 | 53.1 | 1.0409 |
10.58 | 9.75 | 1.0440 | 9.45 | 8.40 | 53.3 | 1.0411 |
10.64 | 9.80 | 1.0442 | 9.50 | 8.45 | 53.5 | 1.0413 |
| | | | | | |
10.70 | 9.86 | 1.0444 | 9.55 | 8.49 | 53.7 | 1.0415 |
10.75 | 9.91 | 1.0447 | 9.60 | 8.53 | 53.9 | 1.0417 |
10.80 | 9.96 | 1.0449 | 9.65 | 8.58 | 54.1 | 1.0419 |
10.86 | 10.01 | 1.0451 | 9.70 | 8.62 | 54.3 | 1.0422 |
10.91 | 10.06 | 1.0453 | 9.75 | 8.67 | 54.5 | 1.0424 |
| | | | | | |
10.97 | 10.11 | 1.0456 | 9.80 | 8.71 | 54.7 | 1.0426 |
11.02 | 10.16 | 1.0458 | 9.85 | 8.75 | 55.0 | 1.0428 |
11.08 | 10.21 | 1.0461 | 9.90 | 8.80 | 55.2 | 1.0430 |
11.14 | 10.26 | 1.0463 | 9.95 | 8.85 | 55.4 | 1.0433 |
11.20 | 10.31 | 1.0465 | 10.00 | 8.89 | 55.6 | 1.0435 |
| | | | | | |
11.25 | 10.37 | 1.0467 | 10.05 | 8.93 | 55.8 | 1.0437 |
11.30 | 10.42 | 1.0469 | 10.10 | 8.98 | 56.0 | 1.0439 |
11.36 | 10.47 | 1.0472 | 10.15 | 9.02 | 56.2 | 1.0441 |
11.41 | 10.52 | 1.0474 | 10.20 | 9.07 | 56.4 | 1.0444 |
11.47 | 10.57 | 1.0476 | 10.25 | 9.11 | 56.6 | 1.0446 |
| | | | | | |
11.53 | 10.63 | 1.0478 | 10.30 | 9.15 | 56.8 | 1.0448 |
11.59 | 10.68 | 1.0481 | 10.35 | 9.20 | 57.0 | 1.0450 |
11.64 | 10.73 | 1.0483 | 10.40 | 9.25 | 57.2 | 1.0452 |
11.70 | 10.78 | 1.0485 | 10.45 | 9.29 | 57.4 | 1.0454 |
11.75 | 10.83 | 1.0487 | 10.50 | 9.33 | 57.6 | 1.0457 |
----------+----------+--------+----------+----------+---------+--------+

TABLE 5.—_Tomato Pulp and Filtered Liquor_—Continued

========================================================================
Whole pulp | Filtrate from pulp |
------------------------------+---------------------+---------+--------+
Solids by drying | | Solids by drying |Immersion| |
---------------------+ +---------------------+refract- | |
_In vacuo_| At |Specific|_In vacuo_| At | ometer |Specific|
at 70° C.| atmo- |gravity | at 70° C.| atmo- |reading | gravity|
| spheric | at | | spheric | at | at |
| pressure | 20° C. | | pressure |17.5° C. | 20° C.|
| 100° C.| | | 100° C | | |
----------+----------+--------+----------+----------+---------+--------+
_Per cent_|_Per cent_| |_Per cent_|_Per cent_| | |
11.81 | 10.89 | 1.0490 | 10.55 | 9.38 | 57.8 | 1.0459 |
11.87 | 10.94 | 1.0492 | 10.60 | 9.42 | 58.0 | 1.0461 |
11.93 | 10.99 | 1.0494 | 10.65 | 9.47 | 58.2 | 1.0463 |
11.99 | 11.04 | 1.0496 | 10.70 | 9.51 | 58.4 | 1.0465 |
12.05 | 11.09 | 1.0499 | 10.75 | 9.55 | 58.6 | 1.0467 |
| | | | | | |
12.10 | 11.15 | 1.0501 | 10.80 | 9.60 | 58.8 | 1.0469 |
12.15 | 11.20 | 1.0503 | 10.85 | 9.65 | 59.0 | 1.0471 |
12.21 | 11.25 | 1.0505 | 10.90 | 9.70 | 59.2 | 1.047| |
12.26 | 11.30 | 1.0508 | 10.95 | 9.74 | 59.4 | 1.0476 |
12.32 | 11.35 | 1.0510 | 11.00 | 9.78 | 59.6 | 1.0478 |
| | | | | | |
12.37 | 11.40 | 1.0512 | 11.05 | 9.82 | 59.9 | 1.0480 |
12.43 | 11.45 | 1.0515 | 11.10 | 9.87 | 60.1 | 1.0482 |
12.49 | 11.50 | 1.0517 | 11.15 | 9.92 | 60.3 | 1.0484 |
12.55 | 11.55 | 1.0519 | 11.20 | 9.96 | 60.5 | 1.0487 |
12.60 | 11.60 | 1.0522 | 11.25 | 10.00 | 60.7 | 1.0489 |
| | | | | | |
12.65 | 11.66 | 1.0524 | 11.30 | 10.04 | 60.9 | 1.0491 |
12.71 | 11.71 | 1.0526 | 11.35 | 10.09 | 61.1 | 1.0493 |
12.77 | 11.76 | 1.0528 | 11.40 | 10.13 | 61.3 | 1.0495 |
12.83 | 11.81 | 1.0531 | 11.45 | 10.18 | 61.5 | 1.0498 |
12.88 | 11.86 | 1.0533 | 11.50 | 10.22 | 61.7 | 1.0500 |
| | | | | | |
12.94 | 11.92 | 1.0535 | 11.55 | 10.27 | 61.9 | 1.0502 |
12.99 | 11.97 | 1.0538 | 11.60 | 10.31 | 62.1 | 1.0504 |
13.05 | 12.02 | 1.0540 | 11.65 | 10.35 | 62.3 | 1.0506 |
13.10 | 12.07 | 1.0542 | 11.70 | 10.40 | 62.5 | 1.0508 |
13.16 | 12.12 | 1.0544 | 11.75 | 10.45 | 62.7 | 1.0511 |
| | | | | | |
13.22 | 12.18 | 1.0547 | 11.80 | 10.49 | 62.9 | 1.0513 |
13.27 | 12.23 | 1.0549 | 11.85 | 10.53 | 63.1 | 1.0515 |
13.32 | 12.28 | 1.0551 | 11.90 | 10.58 | 63.3 | 1.0517 |
13.38 | 12.33 | 1.0554 | 11.95 | 10.63 | 63.5 | 1.0519 |
13.44 | 12.38 | 1.0556 | 12.00 | 10.67 | 63.7 | 1.0521 |
----------+----------+--------+----------+----------+---------+--------+

TABLE 5.—_Tomato Pulp and Filtered Liquor_—Continued

The per cent of solids in the filtered liquor obtained by drying _in_ _vacuo_, multiplied by 1.12, gives the per cent of solids in the original pulp obtained by drying _in vacuo_. This relationship is shown in Table 2, in the column headed “Ratio of pulp solids to filtrate solids,” and also in Table 5.

Of the 33 samples shown in Table 2, the result obtained by multiplying the per cent of solids in the filtrate (obtained by drying _in vacuo_) by the factor 1.12 is very nearly identical with the per cent of solids in the pulp (obtained by drying _in vacuo_). In 22 of the 33 samples the difference between these two figures is less than 0.1 per cent. In 17 samples it is less than 0.06 per cent, and in 13 samples it is less than 0.05 per cent. In only two samples does it exceed 0.17 per cent.

(_b_) _By calculation from the specific gravity of the filtrate._—The specific gravity of the filtered liquor may be determined by means of an ordinary pycnometer. From the specific gravity at 20° C., the per cent of solids in the filtrate as determined by drying _in vacuo_ at 70° C. may be obtained from Table 5. It may also be calculated by the following formula, which was derived from the same table:

Per cent Solids in Filtrate = 230 (sp. gr. of filtrate - 1.000).

The per cent of solids in the pulp may also be ascertained from the specific gravity of the filtrate at 20° C., from Table 5. The same results may be obtained from the following formula, which was derived from Table 4:

Per cent Solids in Pulp =
257.5 (sp. gr. of filtrate at 20° C. - 1.000).

It is of interest to note that the table suggested by Windisch for the determination of extract in wine (Bureau of Chemistry, U. S. Dept. Agri., Bull. 107, revised, Table V) may be employed to determine solids in tomato pulp from the specific gravity of the filtered liquor from the same. If the specific gravity of the liquor be determined at 20° C., the figures in the adjoining column, under “Extract,” correspond very closely to the per cent of total solids in the original pulp. A still closer agreement is obtained if the figure 0.05 be deducted from the percentage of extract given in the table.

(_c_) _By calculation from the index of refraction of the filtrate._—The index of refraction of the liquor obtained by filtering tomato pulp may be determined by means of either the Zeiss-Abbé refractometer, or the immersion refractometer at the temperature of 17.5° C. The latter is preferable as it permits of much greater accuracy. The corresponding percentage of solids in the filtrate and the percentage of solids in the pulp from which it is prepared may be ascertained from the index of refraction by Table 5. The per cent of solids in the filtrate may also be calculated from the scale reading of the immersion refractometer at 17.5° C. by the following formula, which is derived from Table 5:

Per cent Solids in Filtrate =
0.258 (scale reading - 15) - 0.0165(scale reading - 26.4).

If the index of refraction has been determined by means of an Abbé refractometer, the per cent of solids in the filtrate may be calculated by the following formula:

Per cent Solids in Filtrate =
666(n_{D} - 1.3332) - 20.7(n_{D} - 1.3376).

The per cent of total solids in tomato pulp may also be ascertained from the index of refraction of the liquor prepared by filtering the pulp as shown in Table 5; or it may be calculated from the immersion refractometer reading by the following formula, which is derived from Table 5:

Per cent Solids in Pulp =
0.289(scale reading of filtrate - 15) - 0.0185(scale reading - 26.4).

If the index of refraction of the filtrate has been determined by means of an Abbé refractometer, the per cent of solids in the pulp may be calculated by the following formula:

Per cent Solids in Pulp = 748(n_{D} - 1.3332) - 25.5(n_{D} - 1.3376).

It is of interest to note that the relation between the index of refraction of the liquor obtained by filtering tomato pulp and the per cent of solids in that liquid is very similar to the relation between the index of refraction and dissolved solids in beer and wine extract, as shown in the table prepared by Wagner.[12]

[12] “Ueber quantitative Bestimmungen wässeriger Lösungen mit dem Zeiss-schen Eintauch-refraktometer,” Table XVII.

In the formula given above, as well as in Table 5, it is assumed that salt is absent. If it be desired to calculate the percentage of solids in a sample containing salt from the index of refraction of the filtrate, it is necessary first to determine the amount of salt present and make correction therefor (see p. 34). For this purpose the table of Wagner[13] may be employed. The correction of the immersion refractometer reading amounts to 0.45 for each tenth per cent of salt present.

[13] _Ibid._, Table I.

This correction is necessary if the percentage of solids be determined by drying, or calculated from specific gravity.

Determination of Insoluble Solids

Transfer 20 grams of the pulp to an eight-ounce nursing bottle, nearly filled with hot water, mix by shaking, and centrifuge until the insoluble matter is collected in a cake in the bottom of the bottle. Transfer the supernatant liquor onto a double, tared filter paper covering the bottom of a Büchner funnel, using suction to facilitate filtration.

Again fill the nursing bottle with hot water, stir the cake of insoluble solids so that it is thoroughly mixed with the water, centrifuge, and decant the supernatant liquor on the filter. Repeat the centrifuging and the filtration of the supernatant liquor once more, and then finally transfer the insoluble solids to the filter paper and thoroughly wash with hot water. Dry the paper and insoluble solids, and weigh. The insoluble solids are quite hydroscopic and the weight must be taken quickly.

Determination of Sugar

The sugar of tomatoes is probably always present as invert sugar. If cane sugar is ever present in the raw product it is doubtless inverted during the concentration of pulp. The per cent of sugar given in Tables 2 and 3 was determined by the method of Munson and Walker.[14]

[14] Methods of Analysis of the Association of Official Agricultural Chemists (1919).

Determination of Acidity

Accurate results cannot be obtained by the titration of tomato products in the presence of the insoluble solids. If it be desired to determine the acidity in the entire sample of tomatoes or tomato pulp rather than in the expressed juice, the insoluble solids should first be removed by the method given in the determination of insoluble solids or by filtration through filter paper. The per cent of acid given in Tables 2 and 3 was obtained by titrating the liquor obtained by filtering the pulp. In products of this nature, the addition of an alkali causes a brownish color which has a tendency to obscure the end point shown by the indicator. To obviate this, the sample should be diluted to at least 200 cc. and a larger amount of indicator employed than is necessary with a clear solution. The following details are suggested.

Dilute 20 grams of the filtrate under examination with over 200 cc. of water. Add at ½ cc. of phenolphthalein solution (prepared by dissolving 1 gram of phenolphthalein in 100 cc. of 95 per cent alcohol) and titrate with sodium hydroxide until the end point is obtained. Add 1 cc. of tenth-normal hydrochloric acid, heat the solution quickly to boiling and boil one minute to expel carbon dioxide. Cool the solution quickly to about room temperature, and then add tenth-normal sodium hydroxide until the end point is obtained. The volume of hydrochloric acid added must, of course, be taken into consideration in the final result. The filtrate may also be titrated direct with tenth-normal sodium hydroxide solution with satisfactory results.

Determination of Salt

This laboratory has been using the following rapid method which gives results agreeing closely with results obtained by the analysis of the ash:

Weigh out 20 grams of pulp, dilute in a volumetric flask to 200 cc., filter and titrate an aliquot portion with standard silver nitrate solution, using potassium chromate as indicator. The acidity of tomato pulp is not sufficient to interfere with this determination.

DETERMINATION OF SPECIFIC GRAVITY[15]

[15] All specific gravities given in this bulletin are on a 20°C/20°C basis.

The specific gravity of tomato pulp is used as one criterion for establishing the value of pulp that is offered for sale and is also used in connection with the manufacture of pulp to determine the point at which evaporation should be stopped.

In the former case there is ample time for making the examination, and conditions may be established which permit a reasonable degree of accuracy in the work.

In the determination of the specific gravity of hot pulp during the process of its evaporation speed is essential, and the conditions of a manufacturing plant do not always permit a high degree of accuracy. It becomes necessary, therefore, to consider what methods may give the highest degree of accuracy obtainable under the conditions of the work and at the same time afford quick results.

Tomato pulp, owing to its high viscosity, retains a large quantity of air bubbles which increase the volume of the pulp and hence interfere with the accuracy of the determination of specific gravity. In working with cold pulp this air may be eliminated by whirling in a centrifuge. With hot pulp that operation is impossible, and the specific gravity must be determined in the presence of the air bubbles mentioned. Moreover, in working with cold pulp the temperature can be more accurately controlled, and the error caused by variation in temperature can be corrected. With hot pulp these conditions cannot be obtained nearly so well. The determination of specific gravity of hot pulp is therefore only roughly approximate at best. Where time permits it is strongly advisable to cool the pulp under conditions that prevent evaporation before determining specific gravity.

The importance of accuracy in the determination of specific gravity in tomato pulp is discussed on page 50.

Methods are given below for the determination of specific gravity in both hot and cold pulp.

When salt has been added, the amount should be determined and a correction applied by deducting .007 from the specific gravity for each per cent of salt present.

(a) <sc>COLD PULP AFTER CENTRIFUGING TO ELIMINATE AIR BUBBLES</sc>

This method may be employed for pulp of any degree of concentration or for unconcentrated cyclone juice. A specific gravity flask such as is shown in Figure 1 is used together with a “2-bottle” Babcock milk tester (the centrifuge referred to below). The flask may be obtained of Eimer & Amend, Third Avenue, 18th to 19th Streets, New York City, or of Emil Greiner & Co., 55 Fulton Street, New York City, and in ordering it should be designated as “specific gravity flask for tomato pulp of Pyrex glass with a capacity of about 125 cc.” The “2-bottle” Babcock milk tester may be obtained of any dairy supply house. It may also be obtained of any dealer in chemical apparatus by designating it as E. & A. No. 1833.

The specific gravity flask may be calibrated as follows:

Obtain the weight of the flask after thoroughly cleaning and drying, fill to overflowing with water (preferably boiled and cooled distilled water) and remove the excess water from the mouth of the flask by means of a straight edge. Wipe dry and weigh immediately. If the flask full of water is weighed at any other temperature than 20° C. (68° F.) a correction must be made to obtain the weight at that temperature. These corrections are as follows:

=============================================
Temperature |Correction to be added
|with flasks having a
| volume of—
----------+----------+------------+----------
Fahrenheit|Centigrade| 125 cc. | 400 cc.
----------+----------+------------+----------
| | _Grams_ | _Grams_
69 | 20.6 | .02 | .05
70 | 21.1 | .03 | .09
71 | 21.7 | .05 | .14
72 | 22.2 | .06 | .20
73 | 22.8 | .08 | .25
| | |
74 | 23.3 | .09 | .30
75 | 23.9 | .11 | .35
76 | 24.4 | .13 | .41
77 | 25.0 | .15 | .47
78 | 25.6 | .17 | .53
| | |
79 | 26.1 | .18 | .59
80 | 26.7 | .20 | .65
81 | 27.2 | .22 | .71
82 | 27.8 | .24 | .77
| | |
83 | 28.3 | .26 | .83
84 | 28.9 | .28 | .89
85 | 29.4 | .30 | .96
86 | 30.0 | .32 | 1.02
----------+----------+------------+----------

If it is desired to use somewhat larger samples and thus secure correspondingly more accurate results, a similar flask, but made somewhat larger (capacity approximately 400 cc.), may be employed. Such a flask, with a diameter of a little over 3 inches, is illustrated in Figure 2. This larger flask will not fit into the Babcock tester, and when it is used a special head for the Babcock tester must be made. Such a head is illustrated in Figure 3, and can be made by any good tinner.

The larger flask shown in Figure 2 holds a heavier weight than the Babcock machine is intended to carry, and the advisability of its use is perhaps questionable. In any case, whatever size flask is used, it is important to build a guard around the centrifuge in order to protect the operator when the apparatus gives way, as it eventually will.

The details of the method of determining specific gravity by the use of this apparatus are as follows:

Fill the flask shown in Figure 1 with the sample of pulp and place in the centrifuge (the Babcock milk tester mentioned above). Place a suitable counterpoise[16] in the other receptacle of the centrifuge. Whirl for from one-half to one minute at a speed of about 1,000 revolutions per minute, that is with the handle turning about 100 revolutions per minute. Because of the air bubbles removed by whirling, the surface of the pulp will now be considerably below the top of the flask. Fill the flask and whirl in the centrifuge again. Repeat this filling and whirling until the flask is practically full of pulp after whirling. Ordinarily two or three separate whirlings are sufficient. Then add a few more drops of pulp so that the pulp comes above the top of the flask, and strike off flush with the top of the flask with a straight edge. Wash the outside of the flask, wipe dry, and weigh. Then read the specific gravity of the pulp from a table prepared, giving the weight of the flask full of pulp and the specific gravity of the pulp in parallel columns, or calculate the specific gravity as described below.

[16] This counterpoise may be prepared with a can or bottle weighted with some heavy material such as solder or shot, until it balances approximately the weight of the can full of pulp. The counterpoise, once prepared, may be left in the centrifuge.

While the weight is being taken a thermometer may be placed in the pulp remaining in the can or dipper from which the flask was filled. If the temperature varies from 68° F. the specific gravity may be corrected by Table 8. In order to use this method the temperature of the pulp should not be below 50° F., or above 86° F.; otherwise, it should be warmed or cooled, as described above.

The method is accurate, simple, easily operated and fairly rapid. To calculate the specific gravity from the weights obtained, the weight of the clean, dry flask and of the water it contains at 68° F. are necessary. The weight of the clean, dry flask is then subtracted from the weight of the flask full of pulp to obtain the net weight of the pulp. This divided by the weight of the water the flask will contain at 68° F., gives the specific gravity.

A table can be constructed readily for each flask, which will give in parallel columns the weight of the flask full of pulp and the corresponding specific gravity. This greatly simplifies the determination, as it eliminates all calculation. When such a table is employed a balance giving actual weights is practically as convenient as one reading specific gravity directly. It has the very important advantage that the balance, weights, and flask may be tested from time to time.

In preparing such a table it is convenient first to draw a curve representing specific gravities of the pulp and corresponding weights of the flask full of pulp of various degrees of specific gravity. The table may then be constructed from the curve.

For instance, let us suppose that the flask weighs 56.00 grams and that when full of water at 68° F. (20° C.) it weighs 176.63 grams. The water contained at the temperature mentioned then weighs (176.63 - 56.00) 120.63 grams. Now the specific gravity of the pulp is its weight compared with the weight of an equal volume of water. Having the figures given above we can easily calculate the weight of the flask filled with pulp of any desired specific gravity. We may therefore calculate the weight of the flask plus pulp of two different specific gravities; mark those points on a sheet of coordinate paper with specific gravity of the pulp entered at the bottom and the weight of flask plus pulp at the side, and a straight line drawn through the two points mentioned gives us the weight of the flask when filled with pulp of any specific gravity.

For instance, if the flask mentioned above be filled with a pulp of the specific gravity of 1.03, the weight of the pulp is (120.63 × 1.03) 124.25 grams. This added to the weight of the flask (56.00 grams) gives us 180.25 grams. Similarly, if the flask be filled with pulp of 1.04 specific gravity the weight of the contents at 68° F. will be (120.63 × 1.04) 125.46 grams. This added to the weight of the flask (56.00 grams) gives 181.46 grams as the weight of flask plus pulp. Now if a sheet of coordinate paper be prepared with specific gravities entered at the bottom and weight of flask plus pulp at the side, these points may be entered. This is done in Figure 4 and the two points mentioned are each indicated by a circle and are connected by a straight line. A table may be constructed from this line, giving the weights of flask plus pulp in one column and the corresponding specific gravity in another.

As an illustration of this there are given below a series of figures illustrating the beginning of the table that could be constructed from Figure 4. If a large sheet of coordinate paper be taken the line shown in Figure 4 may be extended so that a table may be constructed for pulp of all concentrations.

---------+--------
Weight of|Specific
flask and|gravity
pulp |
---------+--------
180.25 | 1.0300
180.31 | 1.0305
180.37 | 1.0310
180.43 | 1.0315
180.49 | 1.0320
180.55 | 1.0325
180.61 | 1.0330
180.67 | 1.0335
---------+--------

The highest degree of accuracy can be secured by filling the flask and making the weighing at exactly 68° F. This is obviously not practicable under factory conditions, however, and satisfactory results can be secured by taking the temperature of the pulp at the time of weighing and correcting for temperature by the use of Table 8. This table gives the correction to be added to the specific gravity when the pulp is taken at temperatures between 68° and 86° F., and the correction to be deducted from the specific gravity for temperatures, between 55° and 68° F. As a matter of principle, correction factors should be avoided as far as practicable, and the smaller the correction factor the more accurate the results will be. This table will be found especially useful in determining the specific gravity of the partly concentrated pulp, as is directed on page 50.

As stated above, in determining specific gravity by this method it is advisable that the reading be made to the second place of decimals. For this purpose an assay pulp balance is suggested. An assay pulp balance carrying a maximum load of 300 grams is listed by dealers in chemical apparatus at $52.50. This balance may be obtained from dealers in chemical apparatus by designating it as “Assay pulp balance E. & A. No. 292, capacity 300 grams.” The same balance, more heavily built, and preferable for that reason, carrying a maximum capacity of 600 grams, is listed at $63.

A satisfactory set of weights, suitable for weighing a cup similar to that shown in Figure 1, may be obtained from any dealer in chemical apparatus by designating it as E. & A. No. 516, “Metric brass weights in wooden box, 200 grams to 1 centigram.” This is listed at $5.50.

For convenience, all of the apparatus necessary for using this method of determining specific gravity is listed below. With the exception of the specific gravity flask this apparatus may be purchased of any dealer in chemical supplies. The specific gravity flasks have not heretofore been available except through this laboratory, which purchased a considerable quantity of them and supplied them to manufacturers of pulp as long as this supply lasted. At the urgent request of the writer, Eimer & Amend and Emil Greiner & Co., both of New York City, have finally stocked this item and stand ready to supply it to those wishing to secure it.

Specific gravity flask for tomato pulp, of Pyrex glass, 1½ × 6¼ inches (outside measurements), capacity about 125 cc.

Two-bottle Babcock milk tester, with 2 brass holders, E. & A. No. 1883.

Assay pulp balance, maximum load 300 grams, E. & A. No. 292.

Metric brass weights in wooden box, 200 grams to 1 centigram, E. & A. No. 516.

Chemical thermometer, 50 to 212° F.[17]

[17] If it is preferred a chemical thermometer with Centigrade scale may be used having a range of from 0 to 100 degrees.

(b) COLD PULP WITHOUT CENTRIFUGING

A method frequently employed for determining the specific gravity of cold pulp is to fill the cup by pouring, strike off with a straight edge, wash the outside, dry and weigh. As ordinarily practiced, this determination is attended by considerable error. If the balance is arranged for reading specific gravity directly, weights should be at hand for determining the accuracy of the balance and the weight of the flask, and both should be checked from time to time. The pulp on being poured into the flask or cup carries with it air bubbles to such an extent as to materially reduce the weight. Attempts to remove these air bubbles without the use of a centrifuge have not been successful. This is shown in Table 7, in the column headed “Pouring cold and whirling by hand.” The figures given in this column were obtained by weighing the sample after it had been whirled vigorously in the cup shown in Fig. 5 until air bubbles appeared to be eliminated. From 50 to 175 revolutions were given the cup in each of the determinations whose results are shown in this column. Even then it will be noted by comparison with Column 1 that the results are low. As the method is ordinarily practiced in the plant, without any attempt to remove the air bubbles by whirling, the results obtained are likely to be less accurate than those shown in the column just mentioned.

Many manufacturers of tomato pulp control the concentration of their product by determining specific gravity when the evaporation is almost completed. They therefore desire the results at the earliest possible moment, and there is no attempt to cool the sample before determining specific gravity, although in that way much more accurate results could be obtained.

When necessary to use this method the hot pulp is poured into the specific gravity flask (Fig. 1 or Fig. 2) by means of a dipper until the flask overflows. The top is then “struck off” with a straight edge and the flask placed in a shallow basin of water and the pulp carefully washed from the outside. The temperature of the pulp remaining in the dipper is then determined by means of a chemical thermometer.

The flask is then dried with a towel, which operation is greatly facilitated by the heat of the pulp. The cooling of the contents of the flask causes contraction, so that after washing the flask is not entirely full. This should be disregarded, as it is desired to determine the weight of the amount of pulp that filled the flask originally. As soon as the outside of the flask is clean and dry the flask and contents are weighed.

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Tomato products: pulp, ketchup, and chili sauce.Chapter II: Part 2

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