Effect of ohmic heating and vacuum impregnation on the quality and microbial stability of osmotically dehydrated strawberries (cv. Camarosa)

The combined effect of osmotic dehydration/ohmic heating (OD–OH) and vacuum impregnation/ohmic heating (VI–OH) on physicochemical and quality parameters of strawberry (a_w, color, firmness and microstructure), as well as on microbial stability of storage samples at 5 and 10 °C, was analyzed. Treatments were carried out with a 65% (w/w) sucrose solution at 30 °C, and ohmic heating at 9.2, 13, and 17 V/cm electric field strengths, corresponding to applied voltages of 70, 100, and 130 V. Dehydrated samples showed that water loss was greater in OD–OH treatments at 17 V/cm. The greatest solute gain, least firmness loss and least color loss were obtained in the VI–OH treatment at 13 V/cm. The shelf-life of strawberries treated with VI–OH at 13 V/cm and stored at 5 °C was extended from 12 d (control samples) to 25 d. Furthermore, the VI–OH treatment at 13 V/cm was the best processing condition for dehydrating strawberries.     

“Cold” electroporation in potato tissue induced by pulsed electric field

This work compares PEF-induced effects in potato tissue at temperatures below and above ambient (T = 2–45 °C). The potato (Agata) was selected for investigation. The PEF treatment using electric field strength E = 200–800 V/cm and bipolar pulses of near-rectangular shape with pulse duration t_p (=100 μs) was applied. The PEF experiments were done under non-isothermal conditions with temperature increase owing to the effect of ohmic heating. The linear temperature dependencies of electrical conductivity of potato tissue with different values of the electrical conductivity disintegration index, Z, were observed. However, the values of the conductivity temperature coefficient, α, at the reference temperature T_r = 25 °C were noticeably different for the intact (α_i = 0.0255 ± 0.0003 °C⁻¹) and completely damaged (α_d = 0.031 ± 0.009 °C⁻¹) potato tissues. This difference was explained by the impact of temperature on the structure of the damaged tissue. The non-isothermal PEF treatment was shown to be an effective tool for electroporation at low temperatures (below ambient). For initial temperature T_i = 2 °C, the most power saving was the PEF treatment at E = 200 V/cm (W ≈ 20–30 kJ/kg), and the PEF treatment at E = 400–800 V/cm required more power consumption (W ≈ 50–80 kJ/kg). The PEF treatment at the fixed value of E (=400 V/cm) showed that the total power consumptions (accounting for PEF treatment and thermal heating), required for high level of tissue disintegration, Z ≈ 0.9, were comparable for initial temperatures T_i = 2 °C (W ≈ 50–80 kJ/kg) and T_i = 20 °C (W ≈ 80 kJ/kg) and were noticeably higher for initial temperature T_i = 40 °C (W ≈ 150 kJ/kg).     

Degradation kinetics of anthocyanins in acerola pulp: Comparison between ohmic and conventional heat treatment

Degradation kinetics of monomeric anthocyanins in acerola pulp during thermal treatment by ohmic and conventional heating was evaluated at different temperatures (75–90 °C). Anthocyanin degradation fitted a first-order reaction model and the rate constants ranged from 5.9 to 19.7 × 10⁻³ min⁻¹. There were no significant differences between the rate constants of the ohmic and the conventional heating processes at all evaluated temperatures. D-Values ranged from 116.7 to 374.5 for ohmic heating and from 134.9 to 390.4 for conventional heating. Values of the free energy of inactivation were within the range of 100.19 and 101.35 kJ mol⁻¹. The enthalpy of activation presented values between 71.79 and 71.94 kJ mol⁻¹ and the entropy of activation ranged from −80.15 to −82.63 J mol⁻¹ K⁻¹. Both heating technologies showed activation energy of 74.8 kJ mol⁻¹ and close values for all thermodynamic parameters, indicating similar mechanisms of degradation.     

Heat treatment of whole milk by the direct joule effect--experimental and numerical approaches to fouling mechanisms

The development of alternative technologies such as the direct Joule effect to pasteurize and sterilize food products is of great scientific and industrial interest. Our objective was 1) to gain insight into the ability to ensure ultra-high-temperature treatment of milk and 2) to investigate the links among thermal, hydraulic, and electrical phenomena in relation to fouling in a direct Joule effect heater. The ohmic heater [OH; (where E is the electrical field and v is the velocity); P (power) = 15 kW] was composed of 5 flat rectangular cells [e (space between the plate and electrode) = 15 mm, w (wall) = 76 mm, and L (length of the plate in plate heat exchanger or electrode) = 246 mm]—3 active cells to ensure heating and 2 (at the extremities) for electrical insulation and the recovery of leakage currents. In the first step, the thermal performance of the OH was investigated vs. the flow regimen [50 < Re (Reynolds number) < 5,000], supplied power (0 < P < 15 kW), and electrical conductivity of fluids (0.1 < σ_20°C < 2 S/m) under clean conditions with model fluids. This protocol enabled a global thermal approach (thermal and electrical balance, modeling of the temperature profile of a fluid) and local analysis of the wall temperature of the electrode. An empirical correlation was established to estimate the temperature gradient, T_w − T_b (where T_w is the wall temperature and T_b is the product temperature) under clean conditions (without fouling) and was used to define operating conditions for pure-volume and direct-resistance heating. In the second step, the ability of OH to ensure the ultra-high-temperature treatment of whole milk was investigated and compared with a plate heat exchanger. Special care was taken to investigate the heat transfer phenomena occurring over a range of temperatures from 105 to 138°C. This temperature range corresponds to the part of the process made critical by protein and mineral fouling. The objectives were 1) to demonstrate the ability of an OH to ensure heat treatment of milk, 2) to study the thermal and hydraulic performance with an increasing power and temperature difference between the inlet and outlet of the OH, 3) to define and validate a criterion to follow heat dissipation efficiency, and 4) to compare the fouling propensity with the different configurations. A heat dissipation coefficient, Rh_CO, was defined and validated to monitor the fouling propensity through global electrical and thermal parameters. Finally, a numerical simulation was developed to analyze heat profiles (wall, deposit, bulk). Because of an increasing Joule effect in the static deposit, the simulation showed how wall overheating would definitively cause fouling to spiral out of control.     

Colour and sarcoplasmic protein evaluation of pork following water bath and ohmic cooking

The objective of this study was to investigate the effects of ohmic (OH) and waterbath (WB) cooking on colour attributes and sarcoplasmic changes of porcine longissimus dorsi muscle at the same endpoint temperatures (EPTs; range 10 °C–80 °C). The OH treatment was carried out at 10 V cm^− 1, and the WB temperature at 85 °C. The colour parameters, deoxymyoglobin% (DeoMb) and metmyoglobin% (MetMb) of the OH-cooked meat were significantly lower (P < 0.05) than those obtained by WB-cooking at the same EPTs (range 60 °C–80 °C). SDS-PAGE analysis showed that the meat treated with WB-cooking had a lower sarcoplasmic protein solubility (5.97 mg/g vs.14.89 mg/g, P < 0.05) and fainter protein bands than that of OH-cooking thus, indicating paler colour, and lower water-holding capacity especially in WB-cooked meat at EPTs above 40 °C. Strong correlations among lightness, browness, metmyoglobin% and soluble proteins were observed in meat following OH-cooking.     

Color changes in fish during grilling – Influences of heat transfer and heating medium on browning color

Samples of red sea bream (Pagrus major) were grilled under radiant (far-infrared radiation, FIR) and convective (superheated steam, SHS) heating. The temperature and color (CIE L^∗, a^∗, and b^∗ values) of the sample surface were monitored over time, using SHS, dry air, and N₂ as heating media. The rate of L^∗ changes was evaluated by treating the browning reaction as first-order. Color changes based on a^∗ and b^∗ values were effectively correlated with the L^∗ value, using empirical equations. A slower reduction in L^∗ for heating with SHS rather than FIR was obtained, probably because of different activation energies (31.5 and 50.7 kJ mol⁻¹) and frequency factors (8.2 and 4759 s⁻¹). The order of reductions in L^∗ was dry air > N₂≒$\fallingdotseq$ SHS. The absence of O₂ in the heating medium could be the reason for the delay in the browning reaction during heating using N₂ and SHS.     

Ohmic cooking of whole turkey meat – Effect of rapid ohmic heating on selected product parameters

Intact turkey meat was cooked using low temperature long time (LTLT) and high temperature short time (HTST) protocols in a combined ohmic/convection system and compared to conventional (CONV) steam cooking. Both ohmic protocols gave a significantly lighter (p < 0.05) and a more uniform colour vs. CONV, while no significant differences (p ? 0.05) were found in texture profile analysis attributes between LTLT and CONV though HTST showed significantly higher attributes (p < 0.05). Cook loss was significantly (p < 0.05) different between treatments (25.2%, 27.9% and 31.3% for LTLT, CONV and HTST). Sensory studies largely confirmed these observations. Cook values (p < 0.05) were lowest for LTLT (4.0) followed by HTST (5.4) and control (8.5). Lipid oxidation and sulphur-flavour-compound development (measured over 7 days) were higher for conventional than ohmic treatments. Overall, these results demonstrate considerable industrial potential for ohmic heating, yielding high quality products with an 8–15-fold reduction in cooking time.     

Trypsin from viscera of vermiculated sailfin catfish, Pterygoplichthys disjunctivus, Weber, 1991: Its purification and characterization

Pterygoplichthys disjunctivus viscera trypsin was purified by fractionation with ammonium sulphate, gel filtration, affinity and ion exchange chromatography (DEAE-Sepharose). Trypsin molecular weight was approximately 27.5 kDa according to SDS–PAGE, shown a single band in zymography. It exhibited maximal activity at pH 9.5 and 40 °C, using N-benzoyl-dl-arginine-p-nitroanilide (BAPNA) as substrate. Enzyme was effectively inhibited by phenyl methyl sulphonyl fluoride (PMSF) (100%), N-α-p-tosyl-l-lysine chloromethyl ketone (TLCK) (85.4%), benzamidine (80.2%), and soybean trypsin inhibitor (75.6%) and partially inhibited by N-tosyl-l-phenylalanine chloromethyl ketone (TPCK) (10.3%), ethylendiaminetetraacetic acid (EDTA) (8.7%) and pepstatin A (1.2%). Enzyme activity was slightly affected by metal ions (Fe²⁺ > Hg²⁺ > Mn²⁺ > K⁺ > Mg²⁺ > Li⁺ > Cu²⁺). Trypsin activity decreased continuously as NaCl concentration increased (0–30%). K_m and k_cat values were 0.13 mM and 1.46 s⁻¹, respectively. Results suggest the enzyme have a potential application where room processing temperatures (25–35 °C) or high salt (30%) concentration are needed, such as in fish sauce production.     

Establishment of kinetic models based on electrical conductivity and freshness indictors for the forecasting of crucian carp (Carassius carassius) freshness

To study quality changes in cold chain circulation, kinetic models were developed to predict the freshness of crucian carp at different temperatures during storage. Electrical conductivity (EC) and freshness indictors (Total volatile basic nitrogen, Total aerobic count and K-value) at 270, 273, 277, 282 and 288 K were accessed to investigate the relation between the crucian carp’s freshness and storage condition (storage temperature and storage time). The kinetic models were developed based on Arrhenius equation. Activation energies (E_A) of EC and Total aerobic count (TAC) are 97.75 and 105.93 kJ mol⁻¹, and corresponding rate constants (k₀) are 5.25 × 10¹⁶ and 5.70 × 10¹⁸, respectively. Relative errors between predicted and values of EC are all within ±5%. The kinetic model established through EC can accurately describe the changes of crucian carp’s quality during the storage within 270-288 K. The kinetic model established based on TAC can accurately forecast crucian carp’s early freshness.     

Novel inactivation methods of Doenjang (fermented soybean paste) by high pressure and ohmic heating

The changes of the total cell number in doenjang (Korean traditional fermented soybean paste) by conventional conduction heating, high pressure non-thermal treatment, and ohmic heating were compared. A total of (10¹–10²) CFU/g cells were decreased by heating at (100–105) °C for 10 min. The inactivation rate was improved when heated to a temperature higher than 110 °C, but the taste, color of doenjang were severely changed. Inactivation by high pressure at (200–800) MPa was not achieved, because the total cell did not reach a reduction of 10¹ CFU/g. The total bacterial counts of 10³ CFU/g were decreased during ohmic heating at 15 V and 60 Hz for 10 min, and showed the most effective inactivation. Therefore, application of the ohmic heating in doenjang with high viscosity can kill target microorganisms related to quality deterioration, and rapid and uniform ohmic heating leads to reduction in sensory quality damage.     

A NaCl-stable serine proteinase from Virgibacillus sp. SK33 isolated from Thai fish sauce

An extracellular proteinase from Virgibacillus sp. SK33, isolated from 1 month-old fish sauce, was purified to electrophoretic homogeneity, using hydrophobic interaction chromatography and hydroxyapatite with purification fold of 2.5 and 7% yield. The anomalous molecular weight (MW) of 19 kDa was obtained from SDS–PAGE, whereas a MW of 33.7 kDa was determined by MALDI-TOF. Optimum conditions for catalytic activity were 55 °C and pH 7.5. The proteinase was strongly inhibited by phenylmethanesulfonyl fluoride (PMSF) and preferentially hydrolysed Suc-Ala-Ala-Pro-Phe-AMC, indicating a serine proteinase with subtilisin-like characteristics. K_m and k_cat of the purified proteinase were 27 μM and 12 s⁻¹, respectively. Proteinase activity, toward both synthetic and anchovy substrates, increased with NaCl up to 25%. The proteinase exhibited high stability in both the absence and presence of NaCl up to 25%. Approximately 2.5-fold increase in activity was observed in the presence of divalent cations, including Ca²⁺, Mg²⁺ and Sr²⁺ at 100 mM. MALDI-TOF MS and LC–ESI-MS/MS analyses, as well as N-terminal sequences, revealed that the purified enzyme did not match microbial proteinases in the database, indicating it to be a novel proteinase.     

Ohmic heating of meats: Electrical conductivities of whole meats and processed meat ingredients

The ohmic heating rate of a food is highly influenced by its electrical conductivity (σ). A survey of σ values of commonly used meat ingredients when dispersed as 5% (w/w) aqueous solutions/suspensions was undertaken. A subset was further investigated at typical usage levels in solution/suspension, and/or when incorporated into beef blends, while σ of selected cuts from five meat species (beef, pork, lamb, chicken and turkey) was also measured. Measurements were made from 5 to 85 °C and showed a linear increase in σ values with increasing temperature. In processed beef, addition of sodium chloride and phosphate (P22) caused a significant increase in σ which in turn would lead to an increase in ohmic heating rates. Furthermore, whole meats with lower endogenous fat or processed meats with the least added fat displayed higher σ and reduced ohmic heating times. In beef maximum σ was observed when fibres were aligned with the current flow.     

Effects of light,temperature and water activity on the kinetics of lipoxidation in almond-based products

Lipoxidation in almond-derived products was investigated using the chemiluminescence (CL) and thiobarbituric acid-reactive substances (TBARS) methods to detect the first and later reaction products, respectively. The effects of light during storage at 5 °C, 22 °C and 40 °C were studied, as well as the effects of combined heat/water activity treatments in the 60–120 °C and 0.38–0.72 range. During storage, light was found to enhance the CL and TBARS values, and specific responses were observed in almond paste and the final Calisson product. During the heating of almond paste, as the initial water activity (a_w) increased, the CL rate constants increased during heating to 60 °C and 80 °C, but interestingly, these values decreased during further heating to 120 °C, whereas the maximum TBARS rate constants occurred at a_w 0.57 at all the heating temperatures tested. The activation energies, based on the CL and TBARS values, decreased specifically when the a_w increased from 0.38 to 0.72, giving overall values ranging from110 kJ mol⁻¹ to 60 kJ mol⁻¹. Likewise, in the same water activity range, the temperature-dependent rate constant enhancing factor (Q₁₀) decreased from 3.3 to 1.6.     

Effects of ageing and low internal temperature of grilling on the formation of heterocyclic amines in beef Longissimus dorsi muscle

The mutagenic heterocyclic amines (HAs) originate in processed proteinaceous food. The effects of ageing (non-aged - i.e. 24 h post mortem vs. 14 and 28 days post mortem kept at 1 °C) and final internal temperature on cooking (T_i, 65 and 80 °C) on the content of HAs in grilled steaks (two-plated grill, temperature of 220 °C) were studied. HA precursors (creatine, creatinine, and free amino acids) and ageing indicators, such as instrumentally measured colour values, pH_ultimate values and length of myofibrilar fragments on raw and cutting values on grilled beef Longissimus dorsi muscles were determined. The muscles originated from eight commercially slaughtered Simmental bulls, 19-20 months old. The content of HAs was determined by a solid-phase extraction procedure. Meat ageing is accompanied by large changes in the chemical composition and structure of muscle tissues. In general, all the ageing indicators and precursors of HAs were influenced by ageing time at the 5% level or less. Creatine content declined significantly (non-aged: 6.00 mg g⁻¹, 14 days: 5.82 mg g⁻¹, and 28 days: 5.55 mg g⁻¹) and creatinine increased with days of ageing (non-aged: 0.19 mg g⁻¹, 14 days: 0.24 mg g⁻¹, and 28 days: 0.26 mg g⁻¹). Higher contents of total free amino acids were determined after 14 and 28 days of storage (28.18 μmol g⁻¹ and 37.59 μmol g⁻¹) than in non-aged beef (19.00 μmol g⁻¹). In this study, two HAs were determined: MeIQx (2-amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline) and PhIP (2—amino-1-methyl-6-phenylimidazo-[4,5-b]pyridine). The content of HAs increases with ageing. At lower T_i, more MeIQx was formed; at higher T_i, more PhIP was formed. MeIQx was present in all samples while PhIP was found only in samples grilled to higher T_i. Samples treated to T_i = 80 °C generally contained less HAs (non-aged meat: 0.20 ng g⁻¹, 14 days: 0.26 ng g⁻¹, and 28 days: 0.28 ng g⁻¹) than samples treated to T_i = 65 °C (non-aged meat: 0.19 ng g⁻¹, 14 days: 0.36 ng g⁻¹, and 28 days: 0.39 ng g⁻¹) on account of MeIQx thermolability.     

Ohmic cooking of whole beef muscle — Evaluation of the impact of a novel rapid ohmic cooking method on product quality

Cylindrical cores of beef semitendinosus (500 g) were cooked in a combined ohmic/convection heating system to low (72 °C, LTLT) and high (95 °C, HTST) target end-point temperatures. A control was also cooked to an end-point temperature of 72 °C at the coldest point. Microbial challenge studies on a model meat matrix confirmed product safety. Hunter L-values showed that ohmically heated meat had significantly (p < 0.05) lighter surface-colours (63.05 (LTLT) and 62.26 (HTST)) relative to the control (56.85). No significant texture differences (p ≥ 0.05) were suggested by Warner–Bratzler peak load values (34.09, 36.37 vs. 35.19 N). Cook loss was significantly (p < 0.05) lower for LTLT samples (29.3%) compared to the other meats (36.3 and 33.8%). Sensory studies largely confirmed these observations. Cook values were lower for LTLT (3.05) while HTST and the control were more comparable (6.09 and 7.71, respectively). These results demonstrate considerable potential for this application of ohmic heating for whole meats.     

Electrical conductivity changes of minced beef–fat blends during ohmic cooking

Minced beef–fat blends having different fat level (2%, 9% and 15%) and full meat-fat samples were ohmically cooked by different voltage gradients (20, 30 and 40 V/cm). Main factors affecting the electrical conductivity were the temperature and the composition of the blends. Although the effect of initial fat content on electrical conductivity was statistically significant, voltage gradient did not affect the electrical conductivity changes during cooking treatment (p > 0.05). The electrical conductivity of the samples increased with increasing temperature up to the critical initial cooking temperature (60–70 °C) depending on the fat level, and then decreased due to structural changes and the increase in the bound water during cooking. The results of the nonlinear mathematical model including the effects of initial fat level and the temperature on the electrical conductivity changes had good agreement (r = 0.952; SEM = 0.009) with the experimental data. The determination of electrical conductivity changes being affected by process variables is crucial to characterize the ohmic cooking of meat products and design of ohmic systems.     

Structural and physical properties of soybean protein isolate films with ohmic heating treatment: Impacts of electric field

The effects of ohmic heating (OH) and conventional heating (CON) on the structural and physical properties of soybean protein isolate (SPI) and SPI films were studied. When the electric field was varied from 0 to 12 V·cm⁻¹, the fluorescence intensity, average particle size, and polydispersity index (PDI) of the OH-SPI were the least at 9 V·cm⁻¹ and increased thereafter. Meanwhile, the free SH-group content and surface hydrophobicity were the maximum at 9 V·cm⁻¹ and decreased thereafter. Moreover, the α-helix content decreased and the random coil content increased noticeably at 12 V·cm⁻¹. In terms of the properties of the SPI films, the mechanical properties and water resistance of the OH-SPI films were superior to those of the CON-SPI films. When the electric field was 9 V·cm⁻¹, the tensile strength of the OH-SPI film increased from 2.76 MPa to 4.34 MPa, and the elongation at break of the OH-SPI films improved. Moreover, the water resistance of the OH-SPI films was the best at this electric field.     

Effects of temperature,solid content and pH on the stability of black carrot anthocyanins

Anthocyanin stability of black carrots was studied at various solid contents (11, 30, 45 and 64° Brix) and pHs (4.3 and 6.0) during both heating, at 70–90 °C, and storage at 4–37 °C. Monomeric anthocyanin degradation fitted a first-order reaction model. Degradation of monomeric anthocyanins increased with increasing solid content during heating, while it decreased during storage. For example, at pH 4.3, half-life periods for anthocyanins at 30, 45 and 64° Brix were, respectively, 8.4, 6.9 and 5.2 h during heating at 80 °C and 18.7, 30.8 and 35.9 weeks during storage at 20 °C. At 30–64° Brix, increasing pH from 4.3 to 6.0 enhanced the degradation of anthocyanins during heating. The effect of pH on thermal stability of anthocyanins was also studied at six different pHs (2.5–7.0) in citrate-phosphate buffer solutions and significant decrease in anthocyanin stability was observed at pHs above 5.0. Higher activation energies (E_a) were obtained during heating than during storage with increasing solid contents. At 30–64° Brix, E_a values ranged from 68.8 to 95.1 kJ mol⁻¹ during heating and from 62.1 to 86.2 kJ mol⁻¹ during storage. Q₁₀ values at 20–37 °C were as high as 3.1 at 45° Brix and 3.6 at 64° Brix.     

Efficacy of neutral electrolyzed water for sanitization of cutting boards used in the preparation of foods

The effectiveness of neutral electrolyzed water (NEW) to sanitize cutting boards used for food preparation was investigated. Cutting boards made of hardwood and bamboo were inoculated with Escherichia coli K12 and Listeria innocua, dried for 1 h, washed, rinsed and sanitized with NEW, sodium hypochlorite (NaClO) solution, or tap water (control). After each washing protocol, surviving bacterial populations were determined. Results showed that both NEW and NaClO sanitizing solutions produced similar levels of bacterial reductions. In manual washing, the population reductions by NEW and NaClO were 3.4 and 3.6 log₁₀ CFU/100 cm² for E. coli, and 4.1 and 3.9 log₁₀ CFU/100 cm² for L. innocua, respectively. In the automatic washing, the reductions by NEW and NaClO were 4.0 and 4.0 log₁₀ CFU/100 cm² for E. coli, and 4.2 and 3.6 log₁₀ CFU/100 cm² for L. innocua, respectively. No significant differences (P > 0.05) were observed in surviving bacteria counts when comparing board material types.     

Tyrosinase inhibitory activity of native plants from central Argentina: Isolation of an active principle from Lithrea molleoides

Screening of 91 native plants from central Argentina was carried out with the aim of finding new sources of anti-tyrosinase compounds. Extracts obtained from Achyrocline satureioides, Artemisia verlotiorum, Cotoneaster glaucophylla, Dalea elegans, Flourensia campestris, Jodina rhombifolia, Kageneckia lanceolata, Lepechinia floribunda, Lepechinia meyenii, Lithrea molleoides, Porlieria microphylla, Pterocaulon alopecuroides, Ruprechtia apetala, Senna aphylla, Sida rhombifolia, Solanum argentinum, Tagetes minuta and Thalictrum decipiens exhibited more than 90% inhibition of tyrosinase monophenolase activity at 1000 μg ml⁻¹. D. elegans,L. meyenii and L. molleoides were the most potent with IC₅₀ values of 0.48, 10.43 and 3.77 μg ml⁻¹, respectively. D. elegans, L. molleoides and T. decipiens also showed more than 90% inhibition of diphenolase activity at 1000 μg ml⁻¹, with the first of these being the most effective (IC₅₀ = 49.27 μg ml⁻¹). (Z,Z)-5-(trideca-4,7-dienyl)-resorcinol (1) was isolated from L. molleoides as an effective tyrosinase inhibitor with l-tyrosine or l-DOPA as substrates (IC₅₀ = 0.49 and 14.94 μg ml⁻¹, respectively). Compound 1 was 37 times more active in monophenolase inhibitory activity than kojic acid used as a reference. Effective extracts as well as (Z,Z)-5-(trideca-4,7-dienyl)-resorcinol could prove to be promising preservative agents for use in the food industry.