Removing paraffin‐based wax coatings from old corrugated containers using supercritical carbon dioxide

Supercritical carbon dioxide (SC‐CO₂) extractions of paraffin‐based wax coatings from saturated and curtain‐coated old corrugated containers (OCC) are reported. Extractions were performed in a 500‐mL reactor (300 bar, 100°C, 50 g CO₂/min and 1 h). Wax removal efficiencies of 98 and 70% for saturated and curtain‐coated OCC, respectively, were obtained. Under similar conditions, extractions in the presence of water resulted in an extraction efficiency of 99% for saturated OCC. Decreasing the operating pressure to 200 bar decreased the extraction efficiency to approximately 50%. Gas chromatography (GC) of the wax coatings on OCC, before and after extraction with SC‐CO₂, showed a slight shift in the molecular weight distribution of the paraffin wax (after SC‐CO₂ extraction) toward higher molecular weights for both saturating wax and curtain‐coating wax. There was no evidence of chemical degradation or modification of the paraffin wax coatings by SC‐CO₂. The packing density, packing arrangement, and dimensions of the curtain‐coated OCC in the extraction apparatus affected the extraction efficiency. Loose packing compared to tight packing, 1 × 1 cm squares versus 1 × 20 cm strips, had higher extraction efficiencies; a random packing arrangement was better than packing with the fluting material in the direction of SC‐CO₂ flow. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2699–2704, 2002     

Ethanol-Modified Supercritical Carbon Dioxide Extraction of the Bioactive Lipid Components of <Emphasis Type="Italic">Camelina sativa</Emphasis> Seed

Camelina sativa seed is an underutilized oil source that attracts a growing interest, but it requires more research on its composition and processing. Its high omega‐3 content and growing demand for clean food processing technologies make conventional oil extraction less attractive. In this study, the effect of extraction methods on the bioactive lipid composition of the camelina seed lipid was investigated, and its bioactive lipid composition was modified at the extraction stage using ethanol‐modified supercritical carbon dioxide (SC‐CO₂). Ethanol‐modified SC‐CO₂ extractions were carried out at varying temperatures (50 and 70 °C), pressures (35 and 45 MPa), and ethanol concentrations (0–10%, w/w), and were compared to SC‐CO₂, cold press, and hexane extraction. The highest total lipid yield (37.6%) was at 45 MPa/70 °C/10% (w/w) ethanol. Phospholipids and phenolic content increased significantly with ethanol‐modified SC‐CO₂ (p < 0.05). SC‐CO₂ with 10% (w/w) ethanol concentration selectively increased phosphatidylcholine (PC) content. Apparent solubility of camelina seed lipids in SC‐CO₂, determined using the Chrastil model, ranged from 0.0065 kg oil/kg CO₂ (35 MPa/50 °C) to 0.0133 kg oil/kg CO₂ (45 MPa/70 °C). Ethanol‐modified SC‐CO₂ extraction allowed modification of the lipid composition that was not possible with the conventional extraction methods. This is a promising green method for extraction and fractionation of camelina seed lipids to separate and enrich its bioactives.     

Comparison of supercritical CO2 and hexane extraction of lipids from sorghum distillers grains

Total yields and compositions of sorghum dried distillers grains with solubles (DDGS) lipids obtained by supercritical CO₂ (SC‐CO₂) extraction were compared with those obtained by recirculated solvent extraction (RSE) with hexane. The total yield of lipids obtained by SC‐CO₂ extraction at 27.5 MPa and 70 °C was 150 g lipids/kg DDGS, while the yield obtained by RSE with hexane at 69 °C was only 85 g lipids/kg DDGS. The contents of four high‐value compounds, i.e., policosanols, phytosterols, free fatty acids (FFA) and tocols, in the lipids obtained by SC‐CO₂ extraction were 31.2, 15.6, 155.3 and 0.50 mg/g at 27.5 MPa and 70 °C, compared to 26.6, 9.6, 57.3 and 0.03 mg/g for RSE with hexane at 69 °C. The profiles of phytosterols and FFA in the sorghum DDGS lipids were relatively independent of the extraction methods and operating conditions.     

Identification of Unique Aldehyde Dimers in Sorghum Wax Recovered after Fermentation in a Commercial Fuel Ethanol Plant

Sorghum wax can be extracted from the surface of sorghum (Sorghum bicolor) kernels. It is composed mostly of a mixture of unsaturated C₂₈ and C₃₀ alkanes, fatty acids, fatty alcohols, and fatty aldehydes. Like carnauba wax, sorghum wax is a hard wax with a high melting point and it has potential edible and industrial applications. The yield of sorghum wax from the surface of sorghum kernels is 0.2–0.5 g of wax per 100 g of kernels. Sorghum wax can also be recovered from the “distillers oil” which is obtained after fermentation of sorghum (milo) or sorghum/corn blends in dry grind fuel ethanol plants. This distillers sorghum wax can potentially be obtained in yields of up to 10% by chilling the distillers oil to precipitate the wax and then recovering it via centrifugation or filtration. Like sorghum kernel wax, distillers sorghum wax is mainly composed of C₂₈ and C₃₀ alkanes, alcohols, and aldehydes in the molecular weight (MW) range of 350–450. However, we found that 7–49% w/w of distillers sorghum wax is composed of larger wax components with MW of 799–912. Analysis via high-resolution atmospheric pressure chemical ionization mass spectrometry (APCI) and gas chromatography with electron ionization mass spectrometry (GC/MS-EI) resulted in exact mass data and fragmentation patterns that suggested that these high MW compounds are monounsaturated fatty aldehyde dimers, likely formed by aldol condensation. Further confirmation supporting the GC/MS data for the aldol reaction was obtained by comparison with similar aldol products.     

Supercritical carbon dioxide extraction in membrane formation by thermally induced phase separation

In this study, a novel and environmentally friendly extracting method, supercritical carbon dioxide (SC‐CO₂) extraction, was investigated in the thermally induced phase separation (TIPS) process for making microporous membranes. In the SC‐CO₂ extraction, the effects of extraction time, pressure, and temperature on the extraction fraction, membrane morphology, and membrane performance were investigated. It was concluded that with extraction conditions of 18 MPa, 35°C and 2 h, the porous membrane had the highest extraction fraction. There was a close relationship between membrane performance and the extraction conditions of SC‐CO₂, and it is possible to tailor membrane performance through the choice of extraction conditions. Compared with traditional solvent extraction, a dry membrane treated by SC‐CO₂ extraction has much less shrinkage and greater water permeability, whereas the degree of crystallization of a membrane extracted by SC‐CO₂ is slightly greater than that extracted by ethanol. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1632–1639, 2007     

Characterisation of acorn oils extracted by hexane and by supercritical carbon dioxide

Acorn fruit oils from two species of oak, Quercus rotundifolia L. (holm‐oak) and Quercus suber L. (cork‐oak), were extracted by n‐hexane. The acorn fruit of Quercus rotundifolia L. was also extracted by supercritical CO₂ at 18 MPa and 313 K, a superficial velocity of 2.5 × 10^?4 ms^?1, and a particle size diameter of 2.7 × 10^?4 m. The oils were characterised in terms of fatty acids, triglycerides, sterols, tocopherols, and phospholipids. The main fatty acid in both fruit species was oleic acid (about 65%), followed by linoleic acid (about 16.5–17%) and palmitic acid (about 12.1–13.4%). The main triglyceride found in acorn oils was the OOO (oleic, oleic, oleic) triglyceride (33–38%), followed by the POO (palmitic, oleic, oleic) triglyceride (12.6–18.2%). In terms of sterols, the main component in acorn oils of both species was β‐sitosterol (83.5–89%), followed by stigmasterol (about 3%). However, in Quercus suber L., acorn oil was found to consist to 10.2% of campesterol. The amount of cholesterol was low (0.27% for the Quercus rotundifolia L. oil extracted by supercritical fluid extraction, and 0.18% for the oil extracted by n‐hexane). The Quercus suber L. acorn oil presented 0.1% of cholesterol. The total amount of tocopherols in Quercus rotundifolia L. acorn oils was almost the same when the oil was extracted by n‐hexane (973 mg/kg oil) or by supercritical CO₂ (1006 mg/kg oil). The Quercus suber L. acorn oil presented a high value of total tocopherols (1486 mg/kg oil). The supercritical CO₂ did not extract the phospholipids. The amount of phospholipids was very similar for both species of oak acorn oils extracted by n‐hexane. Oxidative stability was also studied, by using the peroxide value and the Rancimat method, revealing that all the oils were significantly protected against oxidation. The influence of storage, under several conditions, on the oxidative stability was also studied. The Quercus rotundifolia L. oil extracted by n‐hexane was better protected against oxidation after a few days of storage at 60 °C.     

Activation of lipase by sol–gel coating with hydrophobic alkyl‐substituted silicates in supercritical carbon dioxide

BACKGROUND: Sol–gel entrapment of lipases is usually performed in an aqueous solution. A novel method of sol–gel coating of lipase in supercritical carbon dioxide (SC‐CO₂) is proposed. RESULTS: Crude lipase powder (Rhizopus oryzae) coated with hydrophobic silicates, derived from dimethyldimethoxysilane and tetramethoxysilane in SC‐CO₂ at 35 °C and 15 MPa, exhibited 5–7 times higher esterification activity than that prepared via an aqueous sol–gel route. Lipase immobilized in a methyl‐substituted silica monolith was also highly activated by sol–gel coating using the same silica precursors in SC‐CO₂. CONCLUSION: Sol– gel coating in SC‐CO₂, of lipases in powder and immobilized forms with hydrophobic alkyl‐substituted silicates provides an efficient tool for the enhancement of enzymatic activities in non‐aqueous media. Copyright © 2009 Society of Chemical Industry     

Storage of sunflower‐seeds: variation on the wax content of the oil

Storage conditions of oil seeds before industrial extraction might influence the quality of the crude oil. The objective of this work was to study the influence of sunflower seed storage conditions (temperature and time) on the quality of the resulting oil in terms of its wax content and composition. Sunflower seeds were stored under different conditions, 10, 21 and 37 °C, in sealed recipients. Extractions of the seeds with hexane were made to obtain the oil at different storage times. The amount of oil extracted (25–40%) showed no significant differences with storage conditions. Wax content of the samples was determined with two different methods (laser polarized turbidimetry and microscopy), and results showed that wax concentration increased with storage conditions (time and temperature). Composition of wax components, determined using capillary gas chromatography, during storage was approximately constant for C₃₅–C₃₉ and showed significant differences for C₄₀–C₄₈ components. Waxes with high carbon number cause more turbidity than waxes with low carbon number, due to their higher melting point, resulting in a low‐quality crude oil and therefore in variations in processing conditions during the oil refining. According to the data showed in this study, seed storage at low temperatures during short periods of time may be the more adequate conditions to obtain high‐quality oil.     

Middle distillates production via Fischer–Tropsch synthesis with integrated upgrading under supercritical conditions

A vertically aligned fixed‐bed reactor system with a cascade of three sequential catalyst beds has been used to incorporate Fischer–Tropsch synthesis (FTS) in the first bed, oligomerization (O) in the second bed, and hydrocracking/isomerization (HC or C) in the third bed (FTOC). Compared to gas phase FTS (GP‐FT) alone, gas phase FTS with the subsequent upgrading beds (GP‐FTOC) is demonstrated to result in a reduction in the olefin selectivity, a reduction in the C₂₆₊ selectivity, and a marked enhancement in the production of branched paraffins and aromatics. Utilization of supercritical hexane as the reaction medium in supercritical FTS (SC‐FT) and supercritical phase FTOC (SC‐FTOC) resulted in a significant reduction in both CH₄ selectivity and CO₂ selectivity. Interestingly, significant amounts of aldehydes and cyclo‐paraffins were collected in SC‐FT and in SC‐FTOC, respectively, while not being observed in traditional gas phase operation (both GP‐FT and GP‐FTOC). © 2014 American Institute of Chemical Engineers AIChE J, 60: 2573–2583, 2014     

Differential scanning calorimetry index for estimating level of saturation in transesterified wax esters

Differential scanning calorimetry (DSC) thermograms of fatty esters can give valuable information on melting characteristics and heats-of-fusion enthalpy (ΔH). A series of jojoba liquid wax esters was constructed by transesterifying native jojoba oil with 5–50% completely hydrogenated jojoba wax esters. This series, when subjected to a standardized DSC tempering method with heating/cooling cycles, exhibited an excellent correlation for level of saturation based on area changes in endothermic ΔH. Endothermic events were recorded for native (ΔH_A) and completely hydrogenated (ΔH_C) jojoba wax esters. A third endotherm, ΔH_B, was observed when they were transesterified. Based on a multiple regression program, the best fit (R²=0.98) using ΔH data was: % saturation=16.847–0.162 (ΔH_A)+0.209 (ΔH_B)+0.600 (ΔH_C). Standard errors for predictions were approximately 1.045 at 0% saturation, 0.770 at 25% saturation, and 1.158 at 50% saturation. Endothermic events A, B, and C each represent the respective diunsaturated, mounounsaturated, and saturated contents of wax esters in the transesterified blends. This was verified by measuring the dropping points for both the native and completely hydrogenated wax esters. These findings provide an index which can predict the degree of saturation in transesterified wax ester blends and serves as a research tool in process and product developments. Presented at the 1995 AOCS Meeting, May 7–11, 1995, San Antonio, Texas. Retired.     

Comparison of two kinds of pumpkin seed oils obtained by supercritical CO2 extraction

The oils from two kinds of pumpkin seeds, black and white ones, were extracted by supercritical CO₂ (SC‐CO₂). The technological variables for SC‐CO₂ extraction were optimized and the resulting oils were analyzed by GC‐MS. As a result, the optimal conditions for SC‐CO₂ extraction were as follows: 25～30 MPa, 45 °C, SC‐CO₂ flow rate of 30～40 kg/h. The main compounds in the resulting oils were 9,12‐octadecadienoic acid, 9‐octadecenoic acid, stearic acid, palmitic acid for both types of pumpkin seeds, however, the black seed oil contains more unsaturated fatty acids (UFA) than the white seed oil. On the other hand, some compounds including heptadecanoic acid (0.27%), tetracosanic acid (0.1%), 9‐dodecaenoic acid (0.45%) and pentadecenoic acid (0.05%) were found in white seed oil but not in black seed oil; while eicosanic acid (0.05%), 11,14‐eicosadienoic acid (0.2%), 11‐octadecenoic acid (0.06%), 7‐hexadecenoic acid (0.02%) and 1,12‐tridecadiene (0.02%) were only found in black seed oil.     

Molecular species of wax esters in jaw fat of atlantic bottlenose dolphin,Tursiops truncatus

The jaw fat of the Atlantic bottlenose dolphin (Tursiops truncatus) contains unusual wax esters which can be separated into short chain (<C₂₄) and long chain (>C₂₄) fractions by thin layer chromatography. The short chain wax esters (28 wt. %) have been characterized as a 72∶24∶4 mixture of isovaleroyl, isobutoryl, and 2-methylbutyrol, esters of C₁₄–C₁₈ n- and iso-alcohols. The intact <C₂₄ esters have been resolved into individual molecular species by gas liquid chromatography on open-tubular polyester columns. The long chain wax esters (12 wt. %) contain C₁₀–C₂₂ n- and iso-acids esterified to the same C₁₄–C₁₈ n- and iso-alcohols. Gas liquid chromatography of the intact, hydrogenated >C₂₄ esters on a short JXR column has characterized them according to carbon number and the number of methyl branches they contain.     

Esterified alkan-1-ols and alkan-2-ols in barley epicuticular wax

The epicuticular wax on all barley organs is characterized by the presence of long chain esters which have alkan-1-ols as their alcohol moiety (mainly C₃₈−C₄₈). A second type of long chain ester in which alkan-2-ols serve as the alcohol moiety has been identified in the wax from all organs except the awns and leaf blades (mainly C₃₃−C₃₅). Utilizing Silica Gel H column chromatography, a 95% separation of the two ester types was achieved. Unlike alkan-1-ols, the alkan-2-ols (primarily C₁₃ and C₁₅) do not occur free in the wax. Esters isolated from spike minus awn wax consisted of 62% alkan-2-ol and 38% alkan-1-ol containing esters. The isomeric composition of each ester was determined with the aid of gas liquid chromatography-mass spectrometry. In the mass spectra of the alkan-2-ol containing esters, mass ions were absent and the relative intensities of the RCO₂H₂ ⁺, RCO₂H⁺, [R′-1]⁺, and RCO⁺ ions were markedly different from those characteristic for alkan-1-ol containing esters. Since esterified alkan-2-ols occur only in those waxes having β-diketones, a close biosynthetic relationship between these two lipid classes is suggested.     

Properties, composition, and analysis of grain sorghum wax

Grain sorghum wax has been judged to be a potential source of natural wax with properties similar to carnauba wax. Approximately 0.16–0.3% (w/w) wax can be extracted from grain sorghum depending on the efficiency of the organic solvents. Although the melting points of carnauba wax and sorghum wax are similar, i.e., 78–86 and 77–85°C, respectively, they differ in acid values, i.e., 2–10 and 10–16, respectively, and saponification numbers, i.e., 77–95 and 16–49, respectively. Improved knowledge of the properties, composition, and analysis of grain sorghum wax would assist in efforts for industrial application of this product. Major components of sorghum wax are hydrocarbons, wax esters, aldehydes, free fatty alcohols, and FFA. The hydrocarbons consist mainly of C₂₇ and C₂₉, and the aldehydes, alcohols, and acids are mainly C₂₈ and C₃₀. The wax esters are mostly esters of C₂₈ and C₃₀ alcohols and acids.     

Physico‐chemical properties of wax esters synthesised from corresponding alcohols using hydrobromic acid and hydrogen peroxide action

Symmetrical wax esters were prepared directly from the C₁₄–C₂₂ alcohols using HBr and H₂O₂. Conversion of alcohol up to 98% was obtained. Physical properties such as melting point, refractive index, viscosity and specific gravity were determined for these wax esters at different temperatures. The physical properties of the synthetic wax esters were compared with those of some commercial samples of wax esters. The physical properties of the wax esters can be manipulated by starting with commercially available mixtures of alcohols.     

Über die Zusammensetzung des Samenöles aus Traubenholunder (Sambucus racemosa L.)

Composition of the Seed Oil of Clustered Elder (Sambucus racemosa L.) The seeds of clustered elder (Sambucus racemosa L.) contain 28% of an oil. Its separation to groups of components was carried out by adsorption chromatography. Single groups of substances were further analysed by TLC and GLC in combination with physico-chemical methods (IR and MS). Thus the following substances were found and identified: n-alkanes (C₁₇–C₃₃), 2-methyl- and 3-methylalkanes, squalene, a mixture of esters, triglycerides, β-sitosterol, campesterol and a mixture of diglycerides. The conditions for the separation of esters by silica gel column chromatography were also found. The mixture of esters was thus separated into a group of aliphatic wax esters (C₃₄–C₄₄) and four groups of esters of steroidal alcohols (mainly β-sitosterol and campesterol) with aliphatic unsaturated acids (predominantly C_18:1, C_18:2 and C_18:3). In the triglycerides representing the main fraction of the oil (93%), the acids C_16:0, C_18:1, C_18:2 and C_18:3 are present. The same acids were also found in diglycerides.     

Characterization of PVC cable insulation materials and products obtained after removal of additives

Organic solvents cyclohexane, dichloromethane, hexane, and tetrahydrofuran were tested to separate the dioctylphthalate (DOP) as plasticizer from the poly(vinyl chloride) (PVC)‐based materials. It was found that the efficiency of ultrasound‐enhanced hexane extraction of the DOP from PVC is 70% and the efficiency of the separation of the DOP and other compounds from the PVC by dissolution in THF followed by subsequent precipitation was 98–99%. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to characterize the thermal behavior of PVC materials before and after extraction of plasticizers. It was found that during heating in the range 20–800°C the total mass loss measured for the nontreated, extracted, and precipitated PVC samples was 71.6, 66.6, and 97%, respectively. In the temperature range 200–340°C, the release of DOP, HCl, and CO₂ was observed by simultaneous thermogravimetry (TG)/FTIR. The effect of plasticizers on thermal behavior of PVC‐based insulation material was characterized by DSC in the range ?40–140°C. It was found that, concerning the PVC cable insulation material before treatment, the value of the glass transition temperature (T_g) was 1.4°C, whereas for the PVC sample extracted by hexane, the value of T_g was 39.5°C and for the PVC dissolved in THF and subsequently precipitated, the value of T_g was 80.4°C. Moreover, the PVC samples after extraction of plasticizers, fillers, and other agents were tested to characterize their thermal degradation. The TG and FTIR results of chemically nontreated, extracted, and precipitated samples were compared. The release of DOP, HCl, CO₂, and benzene was studied during thermal degradation of the samples by FTIR. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 788–795, 2006     

Molecular analysis of intact preen waxes of Calidris canutus (Aves: Scolopacidae) by gas chromatography/mass spectrometry

The intact preen wax esters of the red knot Calidris canutus were studied with gas chromatography/mass spectrometry (GC/MS) and GC/MS/MS. In this latter technique, transitions from the molecular ion to fragment ions representing the fatty acid moiety of the wax esters were measured, providing additional resolution to the analysis of wax esters. The C₂₁−C₃₂ wax esters are composed of complex mixtures of hundreds of individual isomers. The odd carbon-numbered wax esters are predominantly composed of even carbon-numbered n-alcohols (C₁₄, C₁₆, and C₁₈) esterified predominantly with odd carbon-numbered 2-methyl fatty acids (C₇, C₉, C₁₁, and C₁₃), resulting in relatively simple distributions. The even carbon-numbered wax esters show a far more complex distribution due to a number of factors: (i) Their n-alcohol moieties are not dominated by even carbon-numbered n-alcohol moieties are not dominated by even carbon-numbered n-alcohols esterified with odd carbon-numbered 2-methyl fatty acids, but odd and even carbon-numbered n-alcohols participate in approximately equal amounts; (ii) odd carbon-numbered methyl-branched alcohols participate abundantly in these wax ester clusters; and (iii) with increasing molecular weight, various isomers of the 2,6-, 2,8-, and 2,10-dimethyl branched fatty acids also participate in the even carbon-numbered wax esters. The data demonstrate that there is a clear biosynthetic control on the wax ester composition although the reasons for the complex chemistry of the waxes are not yet understood.     

Supercritical carbon dioxide extraction,purification, and characterization of wax from sorghum and sorghum by-products as an alternative natural wax

The objective of this work was to obtain high purity natural wax from sorghum and by-products of sorghum processing (sorghum dried distillers grains with solubles [DDGS] and sorghum bran) using a green process based on supercritical carbon dioxide (SC-CO₂). SC-CO₂ extractions were carried out at varying temperatures (50, 70°C) and pressures (30, 40 MPa) at a CO₂ flow rate 1 L/min for 120 min. Significantly higher wax yield (4.9%) from DDGS was obtained by SC-CO₂ at 40 MPa/70°C compared with whole kernel (0.6%) and bran (3.3%) (p < 0.05). The yield of the extracts obtained by SC-CO₂ extraction was higher than that of the conventional hexane extraction for all three sorghum sources. The highest fraction of wax in the SC-CO₂ extracts was obtained from whole kernel extracts (89%), whereas it was 53.3% from the DDGS and 26.8% from the bran at the same extraction conditions. SC-CO₂ and hexane extracts from sorghum whole kernel shared a similar melting peak temperature of 76.3–77.9 and 79.7°C, respectively, while DDGS and bran extracts by SC-CO₂ showed a much lower melting temperature in the range of 50.7–61.9°C, indicating the presence of lower melting point components such as triacylglycerols. However, the melting points of the DDGS and bran extracts after ethanol purification were significantly increased with the observed peak temperature of 80.8 and 82.0°C, respectively. While the wax yield from DDGS and bran was higher than that of whole kernel, the sorghum whole kernel feedstock was found to be a more feasible feedstock to obtain higher purity wax.     

The Effects of Insect Extracts and Some Insect-Derived Compounds on the Settling Behavior of Liposcelis bostrychophila

Extracts of whole booklice (Liposcelis bostrychophila)—sequentially extracted in hexane and aqueous 80% methanol (80%MeOH)—repel conspecifics. A methanol-soluble fraction (MFr) of the 80% methanol extract was more repellent than either its corresponding water fraction (WFr) or the hexane extract. The repellent effect of the MFr was repeatable across extracts prepared on different occasions over a 1 month period. Gas chromatography, mass-spectrometry (GC-MS) analyses showed that saturated (C₁₆; C₁₈) monoenoic (C_16:1; C_18:1) and a dienoic fatty acid (C_18:2) and the corresponding methyl esters of all but C_16:1 and C₁₈ constituted approximately 95% and 30%, of the detected compounds in the methanol fractions and the hexane extract, respectively. Qualitative thin layer chromatography showed that cholesterol was present in methanol fractions and the hexane extract, and also enabled tentative identification of triacylglycerols and phospholipids in the methanol fractions. Extracts of wheatgerm, dried skimmed milk powder, active yeast, and wholemeal flour—L. bostrychophila dietary components—were analyzed by GC-MS, and C₁₆, C_18:1 and C_18:2 were detected, indicating that C₁₈ and the methyl esters were not directly extractable and/or that they were products of booklice metabolism. A fatty acid amide (stearamide) previously identified in cuticular extracts of L. bostrychophila was not detected, and therefore was not responsible for the observed biological activity. Pure fatty acids and fatty acid methyl esters repelled settling of L. bostrychophila at 10 mM, with the exception of palmitic and stearic acids, indicating, among other things, a difference between the efficacy of saturated and unsaturated fatty acids. The effect of concentrations <10 mM was less significant, although palmiteoleic acid appeared to be attractive to L. bostrychophila at 0.1 mM. Fatty acids and fatty acid methyl esters were at a much lower concentration than 10 mM in the repellent methanol fractions, indicating that an interaction between known and as yet unidentified compounds is likely. The significance of fatty acids in relation to the biology and behavior of L. bostrychophila and their potential for use in traps and monitoring are discussed.