Rehydration Procedure Research Articles

Exploring how YouTube videos demonstrating preparation of dried wood ear mushrooms could pose food safety risks: a case study

PurposeIn 2020, an outbreak of Salmonella Stanley linked to imported dried wood ear mushrooms affected 55 individuals in the United States of America. These mushrooms, commonly used in Asian cuisine, require processing, like rehydration and cutting, before serving. The US Centres for Disease Control and Prevention advise food preparers to use boiling water for rehydration to inactivate vegetative bacterial pathogens. Little is known about how food handlers prepare this ethnic ingredient and which handling procedures could enable Salmonella proliferation.Design/methodology/approachThis study used content analysis to investigate handling practices for dried wood ear mushrooms as demonstrated in YouTube recipe videos and to identify food safety implications during handling of the product. A total of 125 Chinese- and English-language YouTube videos were analysed.FindingsMajor steps in handling procedures were identified, including rehydration, cutting/tearing and blanching. Around 62% of the videos failed to specify the water temperature for rehydration. Only three videos specified a water temperature of 100 °C for rehydrating the mushrooms, and 36% of the videos did not specify the soaking duration. Only one video showed handwashing, cleaning and sanitising of surfaces when handling the dried wood ear mushrooms.Practical implicationsThis study found that most YouTube videos provided vague and inconsistent descriptions of the rehydration procedure, including water temperature and soaking duration. Food preparers were advised to use boiling water for rehydration to inactivate vegetative bacterial pathogens. However, boiling water alone is insufficient to inactivate all bacterial spores. Extended periods of soaking and storage could be of concern for spore germination and bacterial growth. More validation studies need to be conducted to provide guidance on how to safely handle the mushrooms.Originality/valueThis study will make a distinctive contribution to the field of food safety by being the first to investigate the handling procedure of a unique ethnic food ingredient, dried wood ear mushrooms, which has been linked to a previous outbreak and multiple recalls in the United States of America. The valuable data collected from this study can help target food handling education as well as influence future microbial validation study design and risk assessment.

Water distribution, physicochemical and microstructural properties of scallop adductors as affected by different drying methods

Effect of three drying methods, viz. hot air drying (HAD), heat pump drying (HPD) and vacuum freeze drying (VFD) on the drying kinetics, water composition and distribution, physicochemical and microstructural properties of scallop adductors were investigated. Drying methods significantly affected drying rate following by the order of HAD>VFD>HPD. Low field nuclear magnetic resonance (LF NMR) data demonstrated the transverse relaxation time (T2) of immobilized water was the main component governing the drying process. As drying proceeded, T2 of tightly and loosely bound water maintained a relatively stable state, whereas T2 of free water and immobilized one shifted leftwards. Drying led to an increase in hardness and chewiness, and a decrease in total color difference, adhesiveness and crude protein content. Rehydration ratio was increased with time accompanied by a prompt in the initial period and relatively stable thereafter. Compared to drying process, opposite tendency of LF NMR relaxation properties was observed in scallop adductors during rehydration procedure. HAD resulted in compact structure, severe denaturation and degradation of protein secondary structure, while HPD products had a looser microstructure than that of HAD, and VFD products had the most porous structure.

111 Fertilizing ability of frozen and freeze-dried semen following intracytoplasmic sperm injection of invitro-matured sheep oocytes

Freeze-drying is a novel technique that permits the storage of semen at room temperature for long time periods, retaining their fertilizing capacity. The main objective of this work was to compare the fertilization ability of frozen-thawed (FT) and freeze-dried (FD) ram semen following intracytoplasmic sperm injection (ICSI) of invitro-matured (IVM) sheep oocytes. Oocytes were recovered by slicing the ovaries of slaughtered sheep. Selected cumulus-oocyte complexes (COCs) were IVM for 24h in tissue culture medium 199 (TCM-199) supplemented with 10% heat-treated oestrous sheep serum (ESS), 0.36mM pyruvate, FSH (1IUmL−1), and luteinising hormone (LH; 1IUmL−1) under mineral oil in a humidified atmosphere of 5% CO2, at 38.5°C. Semen was collected from fertile adult rams using an artificial vagina and processed for (1) freezing and thawing (Khalifa and Lymberopoulos, 2013 Cell Tissue Bank 14, 687-698; https://doi.org/10.1007/s10561-012-9357-6) or (2) freeze-drying and rehydration according to Arav et al. (2018 J. Assist. Reprod. Genet. 35, 1149-115; https://doi.org/10.1007/s10815-018-1145-1) protocols. For FD protocol, sperm samples were diluted in a sugar solution of trehalose and sorbitol (LyoB) and dehydrated for 24h. Later, the samples were rehydrated in a warming solution and diluted in TCM-199 before ICSI. After maturation, metaphase II (MII) oocytes with a polar body were injected with FT or FD sperm. Briefly, oocytes were transferred into groups of six in an ICSI dish containing 6-µL drops of holding medium (TCM-199 + 5% fetal bovine serum) and 3-µL drops of PVP for the sperm samples. Injection was carried out with an inverted microscope (Olympus IX73) connected to a micromanipulation system (Narishige) using ICSI pipettes with 7-µm internal diameter. Within 1h, ICSI oocytes were activated with 5 µM ionomycin for 4min and invitro cultured in modified synthetic oviductal fluid medium (Bogliolo et al. 2011 Reprod. Fertil. Dev. 23, 809-817; https://doi.org/10.1071/RD11023). After 17-21h, injected oocytes were fixed and stained in a solution of ethanol Hoechst 33342 and classified as FPN (one female pronucleus and one condensed sperm head), MPN (one male pronucleus and one MII), 2PN (two pronuclei, male and female), 3PN (three or more pronuclei), and NPN (no pronuclei). Data were analysed using analysis of variance (two-way ANOVA) followed by Tukey post hoc test with SAS software, version 9.4. The ICSI-FD group had a higher number of NPN and a lower number of 2PN than did the ICSI-FT group (P<0.05). We think that more technical advances in the FD process as well as the rehydration procedure are necessary to improve the application of FD ovine semen for invitro fertilization by ICSI in sheep, but in any case these results have showed that FD could be a useful tool for the future of invitro embryo production. Table 1.Pronuclear formation at 17-21h post-injection1 Treatment n FPN MPN 2PN 3PN NPN FT 71 9.66±4.12 4.26±1.48 48.13±2.79a 5.97±4.16 31.98±6.75a FD 65 6.16±2.26 1.39±1.39 20.15±4.14b 10.57±6.59 61.73±6.89b a,bValues in the same column with different superscript letters differ significantly (P<0.05). 1Data are presented as mean±s.e.m. FPN=female pronucleus, MPN=one male pronucleus and one metaphase II oocyte, 2PN=two pronuclei, male and female, 3PN=three or more pronuclei, NPN=no pronuclei. Funding was provided by Spanish MINECO Grant AGL2017-85837-R, Spanish MECD pre-doctoral grant FPU15/00773, and Spanish MECD mobility grant EST18/00472 to Irene Menéndez Blanco.

Biofriendly, Stretchable, and Reusable Hydrogel Electronics as Wearable Force Sensors.

The ever-growing overlap between stretchable electronic devices and wearable healthcare applications is igniting the discovery of novel biocompatible and skin-like materials for human-friendly stretchable electronics fabrication. Amongst all potential candidates, hydrogels with excellent biocompatibility and mechanical features close to human tissues are constituting a promising troop for realizing healthcare-oriented electronic functionalities. In this work, based on biocompatible and stretchable hydrogels, a simple paradigm to prototype stretchable electronics with an embedded three-dimensional (3D) helical conductive layout is proposed. Thanks to the 3D helical structure, the hydrogel electronics present satisfactory mechanical and electrical robustness under stretch. In addition, reusability of stretchable electronics is realized with the proposed scenario benefiting from the swelling property of hydrogel. Although losing water would induce structure shrinkage of the hydrogel network and further undermine the function of hydrogel in various applications, the worn-out hydrogel electronics can be reused by simply casting it in water. Through such a rehydration procedure, the dehydrated hydrogel can absorb water from the surrounding and then the hydrogel electronics can achieve resilience in mechanical stretchability and electronic functionality. Also, the ability to reflect pressure and strain changes has revealed the hydrogel electronics to be promising for advanced wearable sensing applications.

Self-assembled PEGylated albumin nanoparticles (SPAN) as a platform for cancer chemotherapy and imaging

Paclitaxel (PTX) is used as a major antitumor agent for the treatment of recurrent and metastatic breast cancer. For the clinical application of PTX, it needs to be dissolved in an oil/detergent-based solvent due to its poor solubility in an aqueous medium. However, the formulation often causes undesirable complications including hypersensitivity reactions and limited tumor distribution, resulting in a lower dose-dependent antitumor effect. Herein, we introduce a facile and oil-free method to prepare albumin-based PTX nanoparticles for efficient systemic cancer therapy using a conjugate of human serum albumin (HSA) and poly(ethyleneglycol) (PEG). PTX were efficiently incorporated in the self-assembled HSA-PEG nanoparticles (HSA-PEG/PTX) using a simple film casting and re-hydration procedure without additional processes such as application of high pressure/shear or chemical crosslinking. The spherical HSA-PEG nanoparticle with a hydrodynamic diameter of ca. 280 nm mediates efficient cellular delivery, leading to comparable or even higher cytotoxicity in various breast cancer cells than that of the commercially available Abraxane®. When systemically administered in a mouse xenograft model for human breast cancer, the HSA-PEG-based nanoparticle formulation exhibited an extended systemic circulation for more than 96 h and enhanced intratumoral accumulation, resulting in a remarkable anticancer effect and prolonged survival of the animals.

Reproducible Preparation of Proteopolymersomes via Sequential Polymer Film Hydration and Membrane Protein Reconstitution.

Film rehydration method is commonly used for membrane protein (MP) reconstitution into block copolymer (BCP), but the lack of control in the rehydration step formed a heterogeneous population of proteopolymersomes that interferes with the characterization and performance of devices incorporating them. To improve the self-assembly of polymersomes with simultaneous MP reconstitution, the study reported herein aimed to understand the effects of different variants of the rehydration procedure on the MP reconstitution into BCP membranes. The model MP used in this study was AquaporinZ (AqpZ), an α-helical MP that has been shown to have a high permeation rate exclusive to water molecules. Comparing four rehydration methods differing in the hydration time (i.e., brief wetting or full hydration) and medium (i.e., in buffer or AqpZ stock solution), prehydration with buffer prior to adding AqpZ was found to be most desirable and reproducible reconstitution method because it gave rise to the highest proportion of well-formed vesicles with intact AqpZ functionality as evidenced by the transmission electron microscopy images, dynamic light scattering, and stopped-flow analyses. The mechanisms by which effective AqpZ reconstitution takes place were also investigated and discussed. Small-angle X-ray scattering analysis shows that hydrating the initially dry multilamellar BCP films allows the separation of lamellae. This is anticipated to increase the membrane fluidity that facilitates a fast and spontaneous integration of AqpZ as the detergent concentration is considerably lowered below its critical micelle concentration. Dilution of detergent can result in precipitation of proteins in the absence of well-fluidized membranes for protein integration that underscores the importance of membrane fluidity in MP reconstitution.

Rehydration methods to recover cysticercoids of the rat tapeworm Hymenolepis diminuta from dry flour beetle carcasses.

Terrestrial arthropods host a variety of helminth parasites, yet quantifying the intensity of infection in these hosts post-mortem is challenging because carcasses may desiccate quickly. We recovered cysticercoids of Hymenolepis diminuta from desiccated flour beetle (Tribolium confusum) carcasses by modifying a published insect rehydration procedure. Without rehydration, carcasses dissected more than 1 day post-mortem had noticeable degradation of cysticercoids. Mild rehydration (soaking in water only for 2 days, or 0.5-10% KOH for 1 h followed by 1 day in water, or 0.5% KOH for 1 day) left carcasses tough and time-consuming to dissect, but all parasites could be recovered and were similar in body size to fresh cysticercoids. Moderate rehydration (5-10% KOH for 1 day) allowed all parasites to be recovered and facilitated dissection by partially dissolving internal organs of the beetle while causing little degradation of the cysticercoids. Harsh rehydration (5-10% KOH for 1 day followed by 5 days in water) not only dissolved internal beetle tissues but also severely damaged cysticercoids, such that parasite counts were unreliable. The degree of initial carcass desiccation had little effect on results following rehydration. However, regardless of treatment used, intact cercomers were rarely retained on rehydrated cysticercoids. Rehydration was less successful on early developmental stages of the parasite, which were recovered reliably only as they neared the cysticercoid stage. This method has utility for studies of parasite-induced mortality by permitting accurate and reliable parasite counts from dead, desiccated hosts.

Short-time xylem relaxation results in reliable quantification of embolism in grapevine petioles and sheds new light on their hydraulic strategy.

In recent years, the validity of embolism quantification methods has been questioned, especially for long-vesseled plants. Some studies have suggested that cutting xylem while under tension, even under water, might generate artificial cavitation. Accordingly, a rehydration procedure prior to hydraulic measurements has been recommended to avoid this artefact. On the other hand, concerns have been raised that xylem refilling might occur when samples are rehydrated. Here, we explore the potential biases affecting embolism quantification for grapevine (Vitis vinifera L.) petioles harvested under tension or after xylem relaxation. We employ direct visualization of embolism through X-ray micro-computed tomography (microCT) to test for the occurrence of fast refilling (artifactually low per cent loss of conductivity (PLC) due to rehydration prior to sample harvest) as well as excision-induced embolism (artifactually high embolism due to air introduction during harvest). Additionally, we compared the response functions of both stomatal regulation and xylem embolism to xylem pressure (Ψx). Short-time (20 min) xylem tension relaxation prior to the hydraulic measurement resulted in a lower degree of embolism than found in samples harvested under native tensions, and yielded xylem vulnerability curves similar to the ones obtained using direct microCT visualization. Much longer periods of hydration (overnight) were required before xylem refilling was observed to occur. In field-grown vines, over 85% of stomatal closure occurred at less negative Ψx than that required to induce 12% PLC. Our results demonstrate that relaxation of xylem tension prior to hydraulic measurement allows for the reliable quantification of native embolism in grapevine petioles. Furthermore, we find that stomatal regulation is sufficiently conservative to avoid transpiration-induced cavitation. These results suggest that grapevines have evolved a strategy of cavitation resistance, rather than one of cavitation tolerance (diurnal cycles of embolism and repair).

Influence of ultrasound on the rehydration of dried sea cucumber (Stichopus japonicus)

Rehydration capacity, water distribution, and microstructure of sea cucumbers subjected to ultrasound-assisted rehydration (UAR) were investigated. Rehydration ratio and water holding capacity (WHC) were found to increase when ultrasound power was increased from 100 W to 300 W, to increase when ultrasound frequency was decreased from 45 KHz to 28 KHz. Nuclear magnetic resonance analysis revealed that water mobility increased with increasing ultrasound power, resulting in more immobilized water and free water, which facilitated better and faster water uptake. Analysis of scanning electron microscope micrographs revealed that with the accelerated water uptake, sea cucumber swelled faster and formed a structure with higher porosity which increased water uptake even faster and led to an accelerated rehydration and higher WHC. Combined with UAR, the rehydration efficiency of dried sea cucumber was increased 12-fold, and 44 h were saved in the rehydration procedure without any negative effect on texture.

Recoverability of freeze-dried doxorubicin-releasing chitosan embolic microspheres

The purpose of this study is to investigate the recoverability of freeze-dried chitosan microspheres (MS). The factors influencing the integrity of chitosan MS during freeze-drying and rehydration procedures were determined, with focusing on choosing a suitable rehydration method and a freeze-drying excipient. Mean MS size, size distribution and sphericity of recovered chitosan MS were evaluated. Furthermore, the impacts of freeze-drying and rehydration procedure on the elasticity of chitosan MS were explored and the release profiles were evaluated. The recoverability of lyophilized chitosan MS was largely dependent on rehydration method and freeze-drying excipients. When using the optimized recovery processes, deformable drug-loaded chitosan MS can be rapidly recovered to exhibit the initial physico-mechanical properties such as elasticity. Release profiles also were not significantly changed after rehydration procedure. It is therefore expected drug-loaded chitosan MS can be stably freeze-dried with the prevention of drug release during storage and rapidly recovered to be used as deformable embolic materials possibly applicable for anti-cancer embolotherapy.

外科手術における術前経口補水導入に関する検討

外科手術における術前経口補水導入に関する検討

Rehydration of dehydrated CaFe-L(ayered)D(ouble)H(ydroxide) followed by thermogravimetry, X-ray diffractometry and dielectric relaxation spectroscopy

In this contribution the rehydration process of a dehydrated CaFe-LDH is described with the combination of thermogravimetric (TG), X-ray diffraction (XRD) and dielectric relaxation spectroscopic (DRS) measurements. Dehydration was followed by TG and the major steps were identified. For studying the rehydration procedure the dehydrated samples were treated in the 6–97% relative humidity range at several preset vapour contents at 298K. For equilibration 72h were allowed. Then, the XRD diffractograms and the DRS spectra were registered and the thermal behaviour of the partially rehydrated samples was also studied. From these measurements the various forms of water molecules interacting with the LDH were deduced and their relaxation behaviour in the rehydration procedure is described.

Microstructure of cement paste subject to early carbonation curing

Microstructure of Ordinary Portland Cement paste subjected to early age carbonation curing was studied to examine the effect of early carbonation on performance of paste at different ages. The study was intended to understand the mechanism of concrete carbonation at early age through the microstructure development of its cement paste. Early carbonation was carried out after 18-hour initial controlled air curing. The microstructure characterized by XRD, TGA, 29Si NMR and SEM was correlated to strength gain, CO 2 uptake and pH change. It was found that early carbonation could accelerate early strength while allowing subsequent hydration. The short term carbonation created a microstructure with more strength-contributing solids than conventional hydration. Calcium hydroxide was converted to calcium carbonates, and calcium–silicate–hydrate became intermingled with carbonates, generating an amorphous calcium–silicate–hydrocarbonate binding phase. Carbonation modified C–S–H retained its original gel structure. The re-hydration procedure applied after carbonation was essential in increasing late strength and durability.

Quality evaluation of pineapple fruit during drying process

Pineapple (Anana comosus) slices were dried by hot-air convective drying technique at fixed temperature (45, 60 and 75°C) and constant air velocity of 1.5m/s. The effect of drying conditions (drying time and air temperature) on the pineapple quality was evaluated. The quality of dehydrated pineapple was analyzed by color and texture changes, l-ascorbic acid loss and the ability of water uptake during rehydration procedure. Water uptake during rehydration was described by Page model. Statistical analysis of data revealed not significant difference (p>0.05) among color and mechanical characteristics of pineapple samples dried at different drying temperatures to preset moisture content. Pineapple samples dried at 45°C had better rehydration ability and more l-ascorbic acid retention than those obtained by air drying 75°C. Hence, 45°C drying temperature was best condition for pineapple quality preservation.

Efficacy of Intravenous Ondansetron to Prevent Vomiting Episodes in Acute Gastroenteritis: A Randomized, Double Blind, and Controlled Trial

Acute gastroenteritis is one of the most common infectious diseases of childhood. Its symptoms are vomiting, diarrhea, and dehydration. In the emergency ward, intravenous rather than oral rehydration is usually preferred because of the high likelihood of emesis. Treatments to reduce emesis are of value in improving the rehydration procedure. Our study is a double-blind randomized trial and proposes the use of ondansetron as an antiemetic drug to treat children with acute gas-troenteritis. Seventy-four in-patients, aged 3 months to 15 years, were enrolled and randomly assigned to an ondansetron or placebo group. Inclusion criteria were the diagnosis of acute gastroenteritis and the absence of other diseases or allergies to drugs. A single bolus (0.15 mg/kg) of ondansetron was injected intravenously; normal 0.9% saline solution was used as a placebo. This treatment induced vomiting cessation in the ondansetron group significantly in comparison to the placebo group. The length of the hospital stay and the oral rehydration fluid volume were similar in the two groups and no adverse effects were noticed. Thus, safety, low cost, and overall benefit of ondansetron treatment suggests that this drug can be administered successfully to children with acute gastroenteritis.

A 3D heterometallic metal–organic framework constructed from luminescent building blocks, exhibiting reversible dehydration and rehydration procedure

A novel metal–organic framework constructed from luminescent building block, [Tb(pydc) 3] 3−, and alkaline earth ion has been designed and synthesized. It illustrates a three-dimensional (3D) structure with nano-channels, and shows reversible dehydration and rehydration behavior.

Alpha interferon is a powerful adjuvant for a recombinant protein vaccine against foot-and-mouth disease virus in swine, and an effective stimulus of in vivo immune response

The adjuvant effect of porcine interferon-alpha (PoIFN-alpha) was examined in swine vaccinated with a recombinant FMD protein vaccine named IgG-FMDV, which contains the swine IgG single heavy chain constant region and an immunogenic peptide of serotype O FMDV. The PoIFN-alpha gene was cloned into pcDNA3 vector and the recombinant plasmid was incorporated into cationic liposomes by a dehydration and rehydration procedure to use as an adjuvant, injected together with low-dose IgG-FMDV. This procedure resulted in strong induction of FMDV-specific neutralizing antibody and significant T-cell-mediated immune responses, whereas only a modest humoral and cellular response was observed with low-dose vaccine alone. As an adjuvant for the protein vaccine, PoIFN-alpha induced strong inflammatory cytokines production in vivo and the results denoted that IFN-adjuvant and our vaccines could drive the immune response toward Th1 type responses. The data of ELISA suggests that the recombinant protein vaccine synergizes with the IFN-adjuvant to produce endogenous IFN in vivo. In response to viral challenge, all control animals developed viremia and lesions, whereas all animals received IFN-adjuvant+IgG-FMDV were protected and nonstructural protein antibody in this group could not be detected by 14 days post-challenge (dpc). Our studies indicate that porcine IFN-alpha is a powerful adjuvant for recombinant FMD protein vaccine and could aid in vaccination against FMDV in swine.

Two Measurement Methods of Leaf Dry Matter Content Produce Similar Results in a Broad Range of Species

Leaf dry matter content (LDMC) is widely used as an indicator of plant resource use in plant functional trait databases. Two main methods have been proposed to measure LDMC, which basically differ in the rehydration procedure to which leaves are subjected after harvesting. These are the 'complete rehydration' protocol of Garnier et al. (2001, Functional Ecology 15: 688-695) and the 'partial rehydration' protocol of Vendramini et al. (2002, New Phytologist 154: 147-157). To test differences in LDMC due to the use of different methods, LDMC was measured on 51 native and cultivated species representing a wide range of plant families and growth forms from central-western Argentina, following the complete rehydration and partial rehydration protocols. The LDMC values obtained by both methods were strongly and positively correlated, clearly showing that LDMC is highly conserved between the two procedures. These trends were not altered by the exclusion of plants with non-laminar leaves. Although the complete rehydration method is the safest to measure LDMC, the partial rehydration procedure produces similar results and is faster. It therefore appears as an acceptable option for those situations in which the complete rehydration method cannot be applied. Two notes of caution are given for cases in which different datasets are compared or combined: (1) the discrepancy between the two rehydration protocols is greatest in the case of high-LDMC (succulent or tender) leaves; (2) the results suggest that, when comparing many studies across unrelated datasets, differences in the measurement protocol may be less important than differences among seasons, years and the quality of local habitats.

Influence of dehydration-rehydration process on rheological properties of liquid fruit foods

The effects of the dehydration-rehydration process on the recovering of the original rheological characteristics of the re-hydrating solution were studied. Four different fruit fluid products were investigated: apricot, banana purees, non-pureed citrus fruits, i.e mandarin juice and lemon treacle, respectively. The static rheological behavior of both pureed and non-pureed products was measured for the raw material, i.e. before the drying process, and after the rehydration procedure. First of all, the results show that rehydrated materials have different rheological behaviors from fresh ones, especially in the case of starch added non-pureed products. Such differences can be due to both the stress conditions induced by mechanical drying and successive rehydration or to other factors such as, for example, the starch addition. These results were relevant to quantify the rehydration efficacy of pureed and non-pureed foods, suggesting than more than just one parameter should be controlled for liquid foods when the rehydration procedure is carried out.

Aldol condensation of campholenic aldehyde and MEK over activated hydrotalcites

In this paper, activated Mg-Al hydrotalcites were used as catalysts in the aldol condensation of campholenic aldehyde and methyl ethyl ketone (MEK). These materials represent an attractive alternative to less environmentally friendly liquid bases in a number of base-catalyzed reactions involved in the pharmaceutical and fragrance industries. The presence of basic hydroxyl groups in the interlayer space leads to very active materials. However, the relation between the activity of reconstructed hydrotalcites and the rehydration procedure is still not well understood. Different rehydration protocols in combination with extensive characterization studies were performed, including XRD, SEM, IR spectroscopy and TPD of CH3CN and CH3NO2. The materials were tested as catalysts in the aldol condensation of campholenic aldehyde and MEK, and relationships between the catalytic performance of the activated hydrotalcites and the rehydration procedure were derived. Several factors may influence the activity and selectivity of this reaction, such as the reaction temperature, the molar ratio of the reactants and the degree of rehydration of the hydrotalcite-like catalysts. The selectivity towards the formation of the desired branched isomer increases when performing the reaction at low temperatures.