Stability of probiotic Lactobacillus plantarum in dry microcapsules under accelerated storage conditions

This study investigated the stability of freeze dried and fluid bed dried alginate microcapsules coated with chitosan containing model probiotic bacteria, Lactobacillus plantarum, during storage for up to 45 days at different water activities (0.11, 0.23, 0.40 and 0.70) and temperatures (4, 30 and 37 °C). The loss in cell viability was around 0.8 log in the case of fluid bed drying and around 1.3 in the case of freeze drying, with the former method resulting in dried capsules of smaller size (~ 1 mm vs 1.3 mm), more irregular shape, and with a rougher surface. In both cases, the water activity and water content were less than 0.25 and 10% w/w, respectively, which favours high storage stability. The storage stability studies demonstrated that as the water activity and temperature decreased the survival of the dried encapsulated cells increased. Considerably better survival was observed for fluid bed dried encapsulated cells compared to freeze dried encapsulated cells and freeze dried free cells with 10% sucrose (control), and in some cases, e.g. at 4 and 30 °C at water activities of 0.11, 0.23 and 0.40, there was more than 1 log difference after 45 days, with concentrations higher than 10⁸ CFU/g after 45 days of storage. The results indicate that fluid bed drying is an effective and efficient manufacturing method to produce probiotic containing capsules with enhanced storage stability.     

Radiant energy under vacuum (REV) technology: A novel approach for producing probiotic enriched apple snacks

The feasibility of vacuum impregnation in combination with air drying + radiant energy vacuum (REV) drying to produce shelf stable probiotic enriched apple slices was evaluated. The shelf life of the products was monitored at 25 and 4 °C. The results demonstrated that bacterial stability at 25 °C depended on the dehydration techniques; with the longest shelf life in air drying +REV drying followed by freeze drying and air drying. Storage at 4 °C showed no significant changes in bacterial population up to 180 days in all samples. Sensory properties of the air drying +REV and freeze dried apple slices remained above the acceptable level for 30 days at 25 °C and 180 days at 4 °C. The results also revealed that dried apple slices were able to provide prominent protection to the cells in acidic gastric juice.     

The increased viability of probiotic Lactobacillus salivarius NRRL B-30514 encapsulated in emulsions with multiple lipid-protein-pectin layers

Probiotics have demonstrated various health benefits but have poor stability to sustain food processing and storage conditions, as well as after ingestion. Biopolymer beads are commonly studied to encapsulate probiotic cells to improve their stability, but the millimeter-dimension of these beads may not meet the quality requirement of food products. The aim of this study was to enhance the viability of Lactobacillus salivarius NRRL B-30514 by encapsulation in emulsion droplets with multiple lipid-protein-pectin layers. Spray-dried L. salivarius was suspended in melted anhydrous milk fat that was then emulsified in a neutral aqueous phase with whey protein isolate or sodium caseinate to prepare primary solid/oil/water (S/O/W) emulsions. Subsequently, pectin was electrostatically deposited onto the droplet surface at pH 3.0 to form secondary emulsions. The encapsulation efficiency was up to 90%. After 20-day storage at 4 °C, the viable cell counts of bacteria in secondary emulsions at pH 3.0 and primary emulsions at 7.0 were 3 log higher than the respective free cell controls. After heating at 63 °C for 30 min, free L. salivarius was inactivated to be undetectable, while about 2.0 log CFU/mL was observed for primary (at pH 7.0) and secondary (at pH 3.0) emulsion treatments. Additionally, a 5 log-CFU/g-powder reduction was observed after spray drying free L. salivarius, while a 2 log CFU/g reduction was observed for emulsion treatments with capsules smaller than 20 μm. Furthermore, cross-linking the secondary emulsion with calcium enhanced the viability of L. salivarius after the simulated gastric and intestinal digestions. Therefore, the studied S/O/W emulsion systems may be used to improve the viability of probiotics during processing, storage, and gastrointestinal digestion.     

Effect of cryoprotectants,prebiotics and microencapsulation on survival of probiotic organisms in yoghurt and freeze-dried yoghurt

The survival of probiotic microorganisms including Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus rhamnosus and Bifidobacterium spp. was evaluated in yoghurt and freeze-dried yoghurt after processing and storage. The effectiveness of microencapsulating probiotic organisms as well as adding cryoprotectants and prebiotics in improving their viability was also investigated. The viability of Bifidobacterium infantis 17930 and L. rhamnosus GG was reduced by 0.07 log, while that of L. casei 1520 and Bifidobacterium longum 1941 was reduced by 0.28 and 0.39 log, respectively. There was a 7% improvement in the viability of L. casei 1520 when cryoprotectant ‘Unipectine™ RS 150’ was added at 2.5% (w/v). The prebiotic ‘Raftilose^®P95’ when added at 1.5% w/v to yoghurt improved the viability of the combined selected probiotic organisms by 1.42 log during four weeks of storage at 4 °C. Microencapsulation with alginate improved viability of combined selected probiotic organisms by 0.31 log in freeze-dried yoghurt stored at 21 °C.     

Interactions between formulation and spray drying conditions related to survival of Lactobacillus plantarum WCFS1

Protective solid carriers are commonly added to probiotic cultures prior to drying. Their formulation is not trivial and depends on the drying conditions applied. In this study, we systematically investigated the influence of formulation parameters on the survival of Lactobacillus plantarum WCFS1 after drying. Low molecular weight carbohydrates (less than 2 kDa) with high glass transition temperatures provided the highest level of protection at both low (25 °C) and high (50 °C or higher) drying temperatures. Low molecular weight carbohydrates may provide stabilization by closely interacting with the lipid bilayer of the cell membranes. Meanwhile, carbohydrates with high glass transition temperatures probably provide stabilization via fixation of the cells in a glassy powder. Furthermore, adequate amounts of solid carrier are required to sufficiently stabilize the cells during drying. During drying, crystallization of solid carriers may occur. Depending on the crystal geometry, crystallization can be either beneficial (e.g. with mannitol or sorbitol) or detrimental (e.g. with lactose) to cell survival. Finally, the effect of formulation on cell viability during storage was studied. A decimal reduction time of approximately 300 days was observed when spray dried L. plantarum WCFS1 was stored at temperatures below 40 °C. The outcome of this study was used as a basis to construct a generalized diagram to indicate the combinations of formulation and drying conditions to maximally retain viability and operate dryers at high efficiency.     

Addition of probiotic bacteria in a semi-hard goat cheese (coalho): Survival to simulated gastrointestinal conditions and inhibitory effect against pathogenic bacteria

In this study, the survival of the probiotics Lactobacillus acidophilus (LA-5), Lactobacillus casei subsp. paracasei (L. casei 01) and Bifidobacterium lactis (BB12) incorporated in a Brazilian semi-hard goat cheese (coalho) when exposed to in vitro simulated conditions of digestion was assessed. The inhibitory effects of these probiotic bacteria were also evaluated against Listeria monocytogenes and Staphylococcus aureus in the goat coalho cheese during refrigerated storage. At the end of the in vitro digestion, all of the probiotic tested strains presented decreased (p < 0.05) viable cell counts (5.5–6.0 log cfu/g) with respect to those determined before exposure to the mouth conditions (7–8 log cfu/g). L. casei subsp. paracasei presented inhibition rate of 7.87% and 23.63% against S. aureus on the 14th and 21st day of storage at 10 °C, respectively; against L. monocytogenes these values were 12.96 and 32.99%. Positive inhibition rates of B. lactis toward S. aureus were found on the 1st, 14th and 21st days of storage (16.32%, 10.12% and 3.67%, respectively); and against L. monocytogenes only on the 1st day of storage (3.28%). From these results, goat coalho cheese could be an interesting carrier of probiotic strains of L. acidophilus, L. casei subsp. paracasei and B. lactis. Moreover, L. casei subsp. paracasei, could be used as protective culture for delaying the growth of S. aureus and L. monocytogenes in goat coalho cheese.     

Probiotic stability of yoghurts containing Jerusalem artichoke inulins during refrigerated storage

Experimentally prepared Jerusalem artichoke inulins (JAI) were compared with two commercial chicory root inulins for their prebiotic potentials in media broth model and growth-sustaining ability in non-fat yoghurts. Experimental yoghurts were made with 12% reconstituted skim milk (RSM) supplemented with 4% inulin powders, inoculated with mixed cultures of Lactobacillus casei LC-01, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (1:0.5:0.5 based on supplier’s recommendation) and incubated overnight at 37 °C. Non-supplemented yoghurt was prepared from 16% RSM and used as control. The survival and acidifying activity of lactic and probiotic cultures in all yoghurts were investigated on weekly intervals during the shelf life of 28 days at 4 °C. Incorporation of JAI resulted in improved viability of LC-01, maintaining >7.0 log CFU/g during cold storage but did not affect the viability of yoghurt bacteria in comparison with the control.     

Development of probiotic beads similar to fish eggs

Probiotic foods are mainly restricted to dairy and soy products. This study aimed to develop a new probiotic beads similar to fish eggs, commonly used in oriental cuisine. Beads were produced by the extrusion encapsulation technique with calcium alginate, added to one of the following cultures: Lactobacillus rhamnosus GG ATCC 53103 and Bifidobacterium animalis DN-173 010 and stored for 30 days at 4 °C. The beads were characterized by the size, weight, morphology and viability of the probiotic strains in different storage temperatures and in simulated gastric juice adjusted to different pH values. The beads were also evaluated by a sensorial affective hedonic scale. The beads present a 2.8 mm diameter and a weight of 0.01 g (p > 0.05). Free and encapsulated cells were tolerant to pH 3.0. At pH 2.5 only of the encapsulated cells presented counts above 6 Log colony-forming units per gram (CFU/g). Beads containing L. rhamnosus showed higher viability 10⁷ CFU/g in storage for 30 days under refrigeration. The beads may be stored at abusive temperature for 5 h without loss of viability cells. The probiotic product developed showed an 82.2% acceptability index of overall characteristics and good market potential as a new probiotic product.     

Quality changes of ready-to-eat ginseng chicken porridge during storage at 25 °C

Ready-to-eat (RTE) ginseng chicken porridge was heated in a retort with an F-value of 4.0 after being packaged in a gas-tight plastic tray (PP/EVOH/PP) with top film (PET/PA/CPP). Various quality changes were investigated during the storage for 28 weeks at 25 °C. Over the storage period, microorganisms were not detected above 1.0 log cfu/cm² (detection limit). The viscosity increased sharply from 775 to 2025 cp for initial 4 weeks and increased steadily until 16 weeks, with a slight reduction thereafter. During the 28 weeks of storage, the ratio of residual oxygen and pH decreased from 10.8% and 6.49 to 5.7% and 6.05, while retrogradation degree increased from 0% to 55.9%. Hunter L^⁎, b^⁎, and ΔE values increased until 20 weeks and remained for the rest of storage. Based on sensory, microbiological and physicochemical evaluations, the RTE ginseng chicken porridge could be marketable for at least 24 weeks at 25 °C.     

Fermented minced pepper by high pressure processing,high pressure processing with mild temperature and thermal pasteurization

High pressure processing (HPP) and thermal pasteurization (TP) of fermented minced pepper (FMP) were comparatively evaluated by examining their impacts on microbial load, titratable acid (TA), pH, a_w, firmness, color, capsanthin, ascorbic acid (AA), and biogenic amines (BAs) after processing and during 12 weeks of storage at 25 and 37 °C. The total plate count (TPC) in FMP samples was reduced by 1.48, 0.12 and 1.58 log₁₀ CFU/g after TP (83 °C/15 min), HPP1 (500 MPa/20 °C/5 min) and HPP2 (500 MPa/50 °C/5 min), respectively. The population of spores was reduced by 1.21 log₁₀ CFU/g only after HPP2. During storage at 25 or 37 °C, the TPC in TP, HPP1, and HPP2 samples increased by 0.88/1.21, 0.41/0.62 and 0.60/0.86 log₁₀ CFU/g, respectively, while the spores decreased below the detection limit. The retention of firmness after TP, HPP1 and HPP2 was 36.91, 91.15 and 66.48% respectively, and HPP-treated samples exhibited more retention during the storage. Color of FMP samples was not changed by TP, but slightly changed by HPP1 and HPP2. The content of capsanthin retained 78.99, 93.71 and 88.19% after TP, HPP1 and HPP2, it showed a small decrease during storage. Levels of biogenic amines (BAs) in HPP2 samples were lower than that of TP and HPP1 ones. There were better sensory quality and lower microbial level in HPP-treated samples during storage, indicating that HPP is a better choice for the preservation of FMP.Industrial relevanceConsumption of fermented minced pepper (FMP), as a traditional Chinese food, is becoming increasingly popular. Considering that heat treatment may destroy some heat-sensitive quality of the products, this study evaluated the effects of high pressure processing (HPP) on quality of FMP. Findings of this study could help processors commercialize HPP to replace current thermal processing in industrial production.     

Effects of conventional and nonconventional drying on the stability of Bifidobacterium animalis subsp. lactis INL1

Freeze, spray, vacuum, microwave vacuum‐ and microwave freeze‐drying were applied to Bifidobacterium animalis subsp. lactis INL1. Freeze and microwave freeze‐drying showed the highest survival after drying. When a storage test (25 °C; oxygen) was performed, these cultures were the most sensitive ones at a_w = 0.23, but the addition of lactose improved their stability after 8 weeks. Flow cytometry was useful to assess viability after drying but not during storage. Our results show that dehydration technologies other than freeze‐drying might be suitable alternatives that deserve further investigation for the preservation of sensitive probiotic bacteria. Microwave drying rendered cultures of comparable characteristics to their conventional counterparts, requiring significantly shorter drying times.     

Encapsulation by electrospray coating atomization of probiotic strains

A new encapsulation method termed electrospray coating atomization (ECA) is presented here for the first time as a new encapsulation concept to enhance the viability of dry powders in general and of freeze-dried probiotic strains in particular. A freeze-dried powder of a probiotic strain (~ 10 log cfu/g) was homogeneously electrospray coated with ultrafine particles of different food hydrocolloids of permitted use in supplemented food and nutraceutical products. The water soluble polymer polyvinylpyrrolidone (PVP) was included in the study as reference pharma permitted encapsulation material. The protected microorganisms were stored at different conditions for periods between 10 and 700 days. Significant differences were found during storage at most of the assayed stressing conditions when compared to the freeze-dried uncoated powder. The results show significantly enhanced comparative survivability of the encapsulated material over time after more than one year at room temperature and 23% RH, especially for whey protein concentrate (WPC), resistant maltodextrin (Fibersol) and PVP. The protective effect of WPC, Fibersol and PVP at 37 °C and 23% RH was also demonstrated.Industrial relevanceElectrospray coating atomization (ECA) is proposed as a new processing methodology for the protection of dry forms of probiotics and in general for the protection of functional/active/bioactive added value ingredients used in the food industry. Since the technology is currently in the process of being scaled up it seems of great significant relevance to an industrial level in order to stabilize or further stabilize existing powder form formulations.     

Effect of mild heat pre-treatment with alkaline electrolyzed water on the efficacy of acidic electrolyzed water against Escherichia coli O157:H7 and Salmonella on Lettuce

Cut lettuce dip-inoculated with Escherichia coli O157:H7 and Salmonella was treated with alkaline electrolyzed water (AlEW) at 20°C for 5 min, and subsequently washed with acidic electrolyzed water (AcEW) at 20°C for 5 min. Pre-treatment with AlEW resulted in an approximate 1.8 log₁₀ cfu/g reduction of microbial populations, which was significantly (p⩽0.05) greater than microbial reductions resulting from other pre-treatment solutions, including distilled water and AcEW. Repeated AcEW treatment did not show a significant bacterial reduction. Mildly heated (50°C) sanitizers were compared with normal (20°C) or chilled (4°C) sanitizers for their bactericidal effect. Mildly heated AcEW and chlorinated water (200 ppm free available chlorine) with a treatment period of 1 or 5 min produced equal reductions of pathogenic bacteria of 3 log₁₀ and 4 log₁₀ cfu/g, respectively. The procedure of treating with mildly heated AlEW for 5 min, and subsequent washing with chilled (4°C) AcEW for period of 1 or 5 min resulted in 3–4 log₁₀ cfu/g reductions of both the pathogenic bacterial counts on lettuce. Extending the mild heat pre-treatment time increased the bactericidal effect more than that observed from the subsequent washing time with chilled AcEW. The appearance of the mildly heated lettuce was not deteriorated after the treatment. In this study, we have illustrated the efficacious application of AlEW as a pre-wash agent, and the effective combined use of AlEW and AcEW.     

Stability of microencapsulated Lactobacillus acidophilus and Lactococcus lactis ssp. cremoris during storage at room temperature at low aw

The effect of freeze drying or spray drying, the use of desiccants to maintain the low a_w and the period of storage (at 25 °C) of Lactobacillus acidophilus and Lactococcus lactis ssp. cremoris on survival, acid tolerance, bile tolerance, retention of surface hydrophobicity and retention of β-galactosidase was studied; an estimation of the maximum storage period was also carried out. Sodium caseinate, vegetable oil, glucose, mannitol and fructooligosaccharides were used as protectant of L. acidophilus and L. cremoris during freeze drying or spray drying and during subsequent storage. NaOH, LiCl and silica gel were used as desiccants during 10 weeks of storage of microencapsulated L. acidophilus and L. cremoris kept in an aluminum foil pouch. The results showed that mainly freeze dried L. acidophilus and L. cremoris kept in foil pouch containing NaOH (a_w 0.07) or LiCl (a_w 0.1) showed higher survival (89–94%) than spray dried bacteria kept under the same conditions (86–90%) after 10 weeks of storage (P = 0.0005). Similar results were also showed by acid tolerance, bile tolerance and surface hydrophobicity of freeze-dried or spray-dried L. acidophilus and L. cremoris. Silica gel was less effective in protecting the functional properties of microencapsulated L. acidophilus or L. cremoris with percentage of survival between 81 and 87% at week 10 of the storage. However, retention of β-galactosidase was only influenced by a_w adjusted by desiccators (P < 0.05). Based on forecasting using linear regression, the predicted storage period for freeze dried L. acidophilus, spray dried L. acidophilus and freeze dried L. cremoris kept in foil pouch containing NaOH would be 46, 42 and 42 weeks, respectively; while spray dried L. cremoris under LiCl desiccant would require 39 weeks to achieve minimum required bacterial population of 10⁷ CFU/g.     

Effect of storage on antioxidant activity of freeze-dried potato peels

A study was undertaken with the objective of evaluating the storage stability of the polyphenols and the antioxidant activity in the peel from two varieties of potatoes, Penta and Marcy, grown in Ontario, Canada. Samples were stored at ?20, 4 and 25 °C for 0, 2, 4 and 8 weeks. Peel from Penta variety contained higher levels of total polyphenolic compounds, 2.4 mg/g of peel d.w. compare to Marcy, 1.14 mg/g of peel d.w. Chlorogenic and caffeic acids were the major polyphenolic compounds present in both verities. Levels of polyphenolic compounds in the peel were influenced by storage temperature with maximum loss observed at 25 °C. Storage time caused a decline in the levels of polyphenolic compounds up to 4 weeks at all temperatures followed by a significant increase at the end of week 8. There was a parallel increase in the antioxidant activity of the peel samples during storage and until the end of 8 weeks of storage. At all temperatures of storage, there was a significant relationship (r = 0.43, P ≤ 0.05) between the amount of polyphenolic compound in the peel samples and their antioxidant capacity. Results suggest potato peel as a valuable source of polyphenolic compounds requiring proper storage condition to maintain their antioxidant properties.     

Application of statistical process control,sampling, and validation for producing Listeria monocytogenes-free chicken leg quarters processed in steam followed by impingement cooking

Chicken leg quarters (180–230 g) were processed for 4 min in steam at 99°C and then in an air impingement oven for 24 min at an oven temperature of 232°C, an air velocity of 2 m/s, and a humidity of 60%. The cooked chicken leg quarters were sampled to measure for the end-point internal temperatures. Sampling size in each subgroup for the internal temperature measurements was determined based on a normal distribution at a confidence level of 95%. The process mean, range, and standard deviation at 95% confidence level were 73.9°C, 1.8°C, and 0.9°C, respectively, for the internal temperatures of the cooked chicken leg quarters. The process lethality was validated for up to 7  log₁₀ cfu/g reductions of Listeria monocytogenes in the cooked chicken leg quarters and verified by an inoculation study in which the chicken leg quarters were injected with 0.1 ml of the culture per cm² of the product surface area to contain 7–8 log₁₀ cfu/g of L. monocytogenes. This paper provided an approach for process control, sampling, and validation to reduce pathogens in fully cooked poultry products.     

The effect of kimchi on the microbiological stability of fermented sausage

The effects of kimchi and freeze-dried kimchi-powder added to raw meat mixtures on the microbiological quality of fermented sausage were studied. The results clearly demonstrated that the lactic acid bacteria (LAB) integrated via the addition of kimchi as well as kimchi-powder were well adapted to the new habitat of fermenting sausage, reaching maximum numbers of 8.65–8.80 log₁₀ cfu/g after 1–2 days of fermentation. In all kimchi and kimchi-powder sausages, the growth of Enterobacteriaceae was completely inhibited throughout the processing period (< 2 log₁₀ cfu/g). The sausage batches containing more than 10% kimchi and 2% kimchi-powder showed no growth of S. aureus, whereas the control and another kimchi sausage batch reflected the growth of S. aureus (3.68–4.72 log₁₀ cfu/g). As a result, the addition of kimchi (≥ 10%) and kimchi-powder to the sausage mixture prior to fermentation produced the microbiological stability required for fermented sausages.     

Combinations of nisin with organic acids or salts to control Listeria monocytogenes on sliced pork bologna stored at 4°C in vacuum packages

This study evaluated dipping solutions of nisin with or without organic acids or salts, as inhibitors of Listeria monocytogenes introduced on sliced cooked pork bologna before vacuum packaging and storage at 4°C for 120 days. Inoculated (10²–10³ cfu/cm²) slices were immersed in nisin (5000 IU/ml), or in lactic or acetic acid (1, 3, 5 g/100 ml), sodium acetate or diacetate (3, 5 g/100 ml), and potassium benzoate or sorbate (3 g/100 ml), each combined with nisin. Additional slices were immersed in nisin, inoculated and then immersed in acid or salt solutions without nisin. Nisin reduced L. monocytogenes by 1.0–1.5 log cfu/cm² at treatment (day-0) followed by a listeriostatic effect for 10 days. Thereafter, however, the pathogen multiplied in treatments without acid or salts, with growth being faster on slices immersed in nisin after as compared to before inoculation. Nisin in combination with 3 or 5 g/100 ml acetic acid or sodium diacetate or 3 g/100 ml potassium benzoate, applied individually or as mixtures, did not permit growth before day-90. Other treatments were of variable and lesser effectiveness (20–70 days), whereas in untreated or water-treated (control) bologna L. monocytogenes increased at 6–7 log cfu/cm² at day-20. Based on the antilisterial efficacy and effects of treatments on product pH, nisin with 3 g/100 ml sodium diacetate may be the most promising combination in dipping solutions to control L. monocytogenes on sliced cured pork bologna.     

Apple,grape or orange juice: Which one offers the best substrate for lactobacilli growth? — A screening study on bacteria viability,superoxide dismutase activity,folates production and hedonic characteristics

Fermentation can contribute to improve functional aspects of foods. The first goal of this study was to determine amongst apple, grape and orange juices, the one with the best bacterial growth performance during fermentation by Lactobacillus strains from commercial and artisanal food origins, at 40 °C for 48 h. The juice with the highest bacterial growth was evaluated for bacteria viability during 4 weeks of cold storage, superoxide dismutase (SOD) activity and folates production analyzed through HPLC/fluorimetry. Acceptability of fermented juice was appraised through hedonic analysis. Lactobacilli counts were the highest in apple and the lowest in orange juices at t = 48 h. In most cases, bacteria counts were higher in fermented (5.5 to 9.5 log CFU/ml) than in supplemented apple juices (4.2 to 5.7 log CFU/ml), at the 4th week of cold storage. SOD activity was significantly increased in all apple juices fermented by commercial Lactobacilli strains. Folates were produced in apple juices fermented by Lactobacillus plantarum and Lactobacillus rhamnosus. Apple juice was the best substrate for Lactobacillus growth and, considering bacterial viability and overall acceptance by the panelists, Lactobacillus acidophilus L10 was the most suitable strain for apple juice fermentation.     

Influence of freezing and dehydration of olive leaves (var. Serrana) on extract composition and antioxidant potential

In this work, the effect of the methods used for the freezing and drying of olive leaves on the polyphenol content and antioxidant capacity of the extracts was addressed. Thus, different methods were used to dry olive leaves (fresh or frozen by conventional (? 28 °C) or N₂ freezing): hot air drying at 70 or 120 °C and freeze drying. The extracts were characterized by determining the phenolic content, antioxidant capacity and HPLC-DAD/MS–MS profile.Drying had a significant (p < 0.05) influence on the antioxidant potential of olive leaf extracts. Both the drying and freezing methods significantly (p < 0.05) influenced the concentration of the main polyphenols identified. Hot air drying provided a higher phenolic content, especially in oleuropein, than freeze drying. Thus, drying at 120 °C was the best processing condition. Freezing reduced the antioxidant potential as compared to fresh leaves, probably due to oxidase activation, although its influence was not dependent on the freezing method.