Natural rubber is an essential material, especially for plane and truck tyres but also for medical gloves. Asia ranks first in the production of natural rubber, of which the Hevea tree is currently the sole source. However, it is anticipated that this source alone will not be able to fulfill the growing demand. Guayule, a shrub native to northern Mexico and southern United States, may also contribute. This plant not only contains polyisoprene, but also resin, a mixture of lipids and terpenoids. This review summarizes various aspects of this plant, from the usage history, botanical description, geographical distribution and cultivation practices, down to polyisoprene and resin biosynthesis including their distribution within the plant and molecular composition. Finally, the main processes yielding dry rubber or latex are depicted, as well as the properties of the various extracts along with economic considerations. The aim is to provide a wide picture of current knowledge available about this promising crop, a good feedstock candidate for a multiple-product biorefinery.
This study deals with the covalorization of spent bleaching clay (SBC) and palm fatty acid distillate (PFAD), the by-products of palm oil-refining plants (3 Mt. year −1 ), through soap manufacture. Obtained SBC and PFAD samples show differing acidity and saponification values depending on their content of free fatty acids and of acylglycerols. The SBC sample had an acidity of 60.5% and a saponification value of 182 mg KOH g −1 of oil, and the PFAD sample has an acidity of 88.4% and a saponification value of 204 mg KOH g −1 of oil. Soaps are prepared using the stoichiometric amount of NaOH, under varying proportion of water introduced through the basic solution. The overall reaction (neutralization and saponification) is complete (99.9%) with PFAD, whereas the yield reaches only 56.1% with SBC. When mixing SBC and PFAD, for example under a 1:1 weight ratio, the overall reaction completion (87.7%) is surprisingly higher than expected based on the computed individual reaction yields (78%), showing a synergistic effect of about 10% on the course of the saponification reaction of acylglycerols in SBC. The water content was found to be a critical parameter, 30% w/w of added water providing the highest yield. These results show an innovative way for covalorizing two important by-products of palm oil industrial processing as a single final product. By-products of the physical refining of other oils could also be valorized following the same method.Keywords Palm fatty acid distillate Á Spent bleaching clay Á Palm oil by-product Á Soap J Am Oil Chem Soc (2019) 96: 329-336. Values within the same column having the same or without superscript are not significantly different (P > 0.05); Data are written as mean value and SD. 333 J Am Oil Chem Soc J Am Oil Chem Soc (2019) 96: 329-336
Fortification of vegetable oils with vitamin A for consumers of different socioeconomic status is feasible; however, light protection is needed for better stability.
This study deals with the co-valorization of spent bleaching clay (SBC) and palm fatty acid distillate (PFAD) –by-products of palm oil refining plants- through soap manufacture. Obtained SBC and PFAD samples show differing acidity and saponification values depending on fatty acids and acylglycerols content. Soaps are prepared using the stoichiometric amount of NaOH, under the varying proportion of water introduced through the basic solution. The mixing SBC and PFAD (ratio 1:3), the reaction completion (92.5%) is surprisingly higher than expected, indicating a synergistic effect on the course of the saponification reaction. The water is also a critical parameter, 30% w/w of added water allowing the highest yield. When testing for cleaning efficiency the products having the highest soap content, those from individual by-products give a low microbial count reduction after hand-washing (30-37%). But a much better score (74%) is obtained when using SBC:PFAD soap mixtures. This improvement could be due to abrasive and absorption effects of the clay, combined with the high soap content. The acceptability through a panel test is good for all soaps when formulated with citrus oil. The most active product corresponds to a SBC:PFAD ratio close to the production one in refining plants. Therefore these results provide an easy way for co-valorising these by-products, after further optimizing the saponification reaction in this complex triphasic medium (aqueous solution, oil, clay).
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