Assessment of the technical quality of sugarbeet in Southern Spain.

M. Ruiz-Holst, F. Dominguez Martin, M. Burba, P. Dominguez y Elias and G. Diener,  Zuckerindustrie (2003), pp. 879-887 (German),  continued ....

Discussion:

[9]	Page 882, just above Fig. 3: If [1] will be clarified as a misprint, with "meq" printed instead of "mmol", this will have consequences: Alkalinity or the result of a ionic balance can be expressed usefully as  0.5mmol CaO  or  1mmol NaOH,  but not  1mmol CaO.  A replacement of "meq" by "mmol" for the result of a ionic balance or effective alkalinity equation, without mentioning a valency, is problematic in any way, but this was already done in earlier papers (including our own). If the alkalinity regression of the present paper was indeed based on mmol CaO per 100 g of sucrose, all factors will be bisected, compared to earlier other papers. REMARK:  It is difficult to check a paper without original figures. In future (scientific) beet quality papers at least a set of the first ten samples should be given in a table, together with an average. Otherwise increased numbers of samples will end up in uncontrollable papers. With an average example only, fundamental errors could be claimed to be misprints.
[10]	On pages 882 and 883 two regression equations (2) and (4) are given, with different coefficients of correlation 0.963 and 0.961: (2) for mNS,DiS [unit g NS/100 g S]       (my writing: qNS/S,DiS) (4) for qDiS      [unit %]           (thick juice purity). But the results of these two regression equations are not - as is mentioned in the discussion on page 884 - correlated (r < 1) but directly connected (r = 1) by the following formula: qDiS = 10000 / (100 + mNS,DiS) 88.18 = 10000 / (100 + 13,4) It is difficult to understand why a second regression (4) was applied on the same set of 625 beet samples, which gives a thick juice purity of 88.6 instead of 88.18.
[11]	Page 883, chapter 3.4, after the example: A symbol fDiS, having a value of 1.13, is mentioned and according to the verbal explanation this factor should be used to get the factory ratio of non-sugar/100sugar in thick juice from the calculated ratio: 13.4 * 1.13 = 15.15. The factory thick juice purity is calculated from this increased value as 86.84 = 10000/(100+15.15).   The explanation concerning fD (Fig. 7) is poor.
[12]	Page 882, equation 1: No comment is given in the discussion about the low invert-sugar factor of 0.29. Schiweck et al. found 1.9 after theoretical consideration and we found 1.5 by regression (which is close to 1.9, compared to 0.29). If the regression was done with mmol CaO, according to [9], the factor 0.29 will at least be doubled.
[13]	SUMMARY: The calculation scheme of the paper can be summarized as follows: a) Calculate the individual ratio of non-sugar/100sugar in thick juice b) Calculate preliminary molasses sugar by an average molasses factor 1.15 c) Correct the preliminary molasses sugar for individual alkali addition If a spanish individual farmer delivers beet with normal or even high effective alkalinity, no correction c) will be applied, but his molasses sugar will be calculated with the low average molasses factor 1.15. This factor will not be true with normal beet (alkalinity), which will not cause high lime salts after juice purification. For this individual farmer the molasses factor will be in the range of 1.4 and the molasses sugar, calculated with 1.15, will be too low. REMARK: In our own paper (Cambridge 1991) we proposed a model-calculation with the assumption that all lime salts are compensated with NaOH addition and the molasses factor should be 1.4 in any case. Further, with sufficient glutamine splitting, the "non-sugar NaOH" has nearly no influence on non-sugar/100sugar in thick juice, as long as the non-sugar is calculated from refractometry and polarimetry and not from alkalis. If NaOH is added before the second carbonatation, Na with 23g/meq will replace Ca with 20g/meq in the refractometric signal, and - at constant pH - OH will end up in water.

2004-02-10       G. Pollach