Effectiveness of organic acid,ozonated water and chlorine dippings on microbial reduction and storage quality of fresh‐cut iceberg lettuce

BACKGROUND: The comparative effects of organic (citric and lactic) acids, ozone and chlorine on the microbiological population and quality parameters of fresh-cut lettuce during storage were evaluated. RESULTS: Dipping of lettuce in 100 mg L⁻¹ chlorine solution reduced the numbers of mesophilic and psychrotrophic bacteria and Enterobacteriaceae by 1.7, 2.0 and 1.6 log₁₀ colony-forming units (CFU) g⁻¹ respectively. Treatment of lettuce with citric (5 g L⁻¹) and lactic (5 mL L⁻¹) acid solutions and ozonated water (4 mg L⁻¹) reduced the populations of mesophilic and psychrotrophic bacteria by 1.7 and 1.5 log₁₀ CFU g⁻¹ respectively. Organic acid dippings resulted in lower mesophilic and psychrotrophic counts than ozonated water and chlorine dippings during 12 days of storage. Lactic acid dipping effectively reduced (by 2.2 log₁₀ CFU g⁻¹) and maintained low populations of Enterobacteriaceae on lettuce for the first 6 days of storage. No significant (P > 0.05) changes were observed in the texture and moisture content of lettuce samples dipped in chlorine, organic acids and ozonated water during storage. Colour, β-carotene and vitamin C values of fresh-cut iceberg lettuce did not change significantly (P > 0.05) until day 8. CONCLUSION: Lactic and citric acid and ozonated water dippings could be alternative treatments to chlorine dipping to prolong the shelf life of fresh-cut iceberg lettuce. Copyright © 2007 Society of Chemical Industry     

Effects of aqueous ozone treatments on microbial load reduction and shelf life extension of fresh‐cut apple

Aqueous ozone was first used to take the place of chlorine as fresh‐cut apples sanitiser. Aqueous ozone (1.4 mg L^?1) treatments were evaluated for their effectiveness on microbial growth, quality attributes and shelf life of fresh‐cut apples. The results indicated that aqueous ozone treatments for 5 and 10 min achieved accepted microbial quality and, respectively, reduced total bacteria counts by 1.83 and 2.13 log₁₀CFU g^?1 compared with the control samples on the 12th day. The ethylene production, polyphenol oxidase and peroxidase activities, and total phenol and malondialdehyde contents were reduced by aqueous ozone treatments. In addition, this sanitiser also delayed the quality deterioration of fresh‐cut apples and enhanced their antioxidant capacity. Therefore, it was recommended to sanitise fresh‐cut apples with aqueous ozone (1.4 mg L^?1) for 5 min, which applied to industrial production requirement for both efficiency and costs and could extend the shelf life up to 10 days.     

Effects of ozone and chlorine postharvest treatments on quality of fresh‐cut red bell peppers

The effects of chlorine (200 μL L^?1), ozonated water (1 μL L^?1) and gaseous ozone (0.7 μL L^?1) on physicochemical attributes and microbial quality of minimally processed red bell peppers were studied. In all the experiments, O₂ continuously decreased and CO₂ concentration increased, the pH augmented and a significant softening was observed in all the fruits. By day 14, L* values decreased in all the fruits, with the greatest changes found in the chlorinated samples (approximately 12 units). Peppers treated with the aqueous solutions showed greater changes in the quality attributes with increasing washing times and especially when chlorine was used. The exposure for three min to gaseous O₃ reduced the mesophiles, psychrotrophes and fungal populations of the fresh‐cut peppers in 2.5, 3.3 and 1.8 log units, respectively. Combined with modified atmosphere, this could be an appropriate method to maintain the quality and extend the storage period of minimally processed red bell peppers.     

Microbiological hazards involved in fresh‐cut lettuce processing

BACKGROUND: The increasing consumption of produce all over the world has resulted in increasing concern by the regulatory agencies with respect to the level of safety performed by the processors. The objective of the present study was to investigate the hazards involved in the various steps of fresh‐cut lettuce processing (reception/selection of raw material, washing, rinsing, sanitisation and final product) by means of microbiological analyses of microbial groups used as indicators of hygienic conditions and of pathogens. RESULTS: High microbial loads of mesophilic and psychrotrophic bacteria and Pseudomonas spp. were found in the ram reception (～6 log colony‐forming units (CFU) g^?1), which were reduced by a single logarithmic cycle for the last two microbial groups after the sanitisation step (P < 0.05), the latter being ineffective against the first microbial group (P > 0.05). Lower counts of yeasts and moulds, total coliforms (35 °C) and faecal coliforms (44 °C) were observed in the initial step (3.49–4.53 log CFU g^?1, 0.65–1.55 log most probable number (MPN) g^?1 and 0.50–0.90 log MPN g^?1 respectively), these values increasing significantly after the sanitisation step for yeasts and moulds (～5 log CFU g^?1) but remaining unaltered for coliforms (P > 0.05). Salmonella spp. were not found in any of the experiments carried out, while the presence of Escherichia coli was observed in the final product. CONCLUSIONS : Practices compromising the hygienic quality of the final product during commercial storage were observed and corrective measures suggested. To the best of the authors' knowledge, these are the first data on microbiological safety in Brazilian fresh‐cut processing plants. Copyright © 2008 Society of Chemical Industry     

Comparison of calcium lactate with chlorine as a washing treatment for fresh‐cut lettuce and carrots: quality and nutritional parameters

The efficacies of calcium lactate and chlorine washing treatments of fresh‐cut lettuce and carrots were compared during storage at 4 °C over 10 days. The gas composition of packages, colour, enzyme activity, texture, sensory attributes, microflora and levels of ascorbic acid and carotenoids were evaluated at 1, 3, 7 and 10 days. Calcium lactate treatment was not significantly different to chlorine treatment (p < 0.05) in terms of maintaining colour, texture and acceptability of fresh‐cut lettuce and carrots during the entire storage period. The washing treatments did not affect levels of ascorbic acid of fresh‐cut lettuce or carrots. Carotenoid levels were higher in calcium lactate‐treated carrots than chlorine‐treated samples at the end of storage. Mesophilic, psychrotrophic and lactic acid bacteria counts were not significantly different between treatments for both vegetables. Copyright © 2005 Society of Chemical Industry     

Shelf‐life extension of vacuum‐packaged sea bream (Sparus aurata) fillets by combined γ‐irradiation and refrigeration: microbiological,chemical and sensory changes

The combined effect of γ‐irradiation and refrigeration on the shelf‐life of vacuum‐packaged sea bream (Sparus aurata) fillets was studied by monitoring the microbiological, chemical and sensory changes of non‐irradiated and irradiated fish samples using low‐dose irradiation doses of 1 and 3 kGy. Fish species such as sea bream and sea bass are very popular in the Mediterranean countries due to their high quality characteristics, and their preservation is a constant challenge given their extreme perishability. Irradiation (3 kGy) dramatically reduced populations of bacteria, namely, total viable counts (3 vs 7 log cfu g^?1) for the non‐irradiated samples, Pseudomonas spp (<2 vs 7.6 log cfu g^?1), H₂S‐producing bacteria typical of Shewanella putrefaciens (<2 vs 5.9 log cfu g^?1), Enterobacteriaceae (<2 vs 6.0 log cfu g^?1) and lactic acid bacteria (<2 vs 3.5 log cfu g^?1) after 10 days of storage. The effect was more pronounced at the higher dose (3 kGy). Lactic acid bacteria, Enterobacteriaceae and H₂S‐producing bacteria typical of Shewanella putrefaciens showed higher sensitivity to γ‐radiation than did the rest of the microbial species. Of the chemical indicators of spoilage, Trimethylamine (TMA) values of non‐irradiated sea bream increased very slowly, whereas for irradiated samples significantly lower values were obtained reaching a final value of 7.9 and 6.3 mg N per 100 g muscle at 1 and 3 kGy respectively (day 42). Total volatile basic nitrogen (TVB‐N) values increased slowly attaining a value of 67.3 mg N per 100 g for non‐irradiated sea bream during refrigerated storage, whereas for irradiated fish, lower values of 52.8 and 43.1 mg N per 100 g muscle were recorded (day 42). Thiobarbituric acid (TBA) values for irradiated sea bream samples were higher than respective non‐irradiated fish and increased slowly until day 21 of storage, reaching final values of 1.1 (non‐irradiated), 2.0 (1 kGy) and 2.2 mg malonaldehyde kg^?1 muscle (3 kGy), respectively (day 42). Sensory evaluation showed a good correlation with bacterial populations. On the basis of overall acceptability scores (sensory evaluation) a shelf‐life of 28 days (3 kGy) was obtained for vacuum‐packaged sea bream, compared with a shelf‐life of 9–10 days for the non‐irradiated sample. Copyright © 2004 Society of Chemical Industry     

Quality of fresh‐cut purple‐fleshed sweet potatoes after X‐ray irradiation treatment and refrigerated storage

The effect of X‐ray irradiation on the quality of fresh‐cut, refrigerated purple‐fleshed sweet potato (PFSP) cubes was investigated. Packaged sweet potato cubes were treated with 0, 250, 500, 750 or 1000 Gy X‐ray irradiation and stored at 4 ± 1 °C for 14 days. After 14 days, total aerobic bacteria counts were 4.1 and 3.2 log₁₀ CFU g^?1, and mould–yeast counts were 3.3 and 3.0 log₁₀ CFU g^?1 in 750 and 1000 Gy treated samples, respectively. Doses up to 1000 Gy did not affect the firmness, moisture content and anthocyanin content of PFSP cubes throughout storage. PFSP cubes' flesh colour did not change during the first week of storage, but lightness (L*) increased after 14 days. Also, irradiation doses at 750 and 1000 Gy decreased saturation (C*) significantly, producing duller flesh colour than controls. Results indicate that X‐ray irradiation treatment at doses up to 1000 Gy can reduce microbial populations while maintaining the physical quality and anthocyanin content of PFSP cubes up to 14 days of storage.     

Antioxidant activity of pomegranate rind powder extract in cooked chicken patties

The radical scavenging activity, reducing power and phenolic composition of pomegranate rind powder extract (RP) were determined and antioxidant properties of RP was evaluated in cooked chicken patties compared with vitamin C (VC) during refrigerated storage. Freshly minced chicken meat were assigned to one of the following six treatments: control (meat without any antioxidant); RP 5, RP 10, RP 15 and RP 20 (5, 10, 15 and 20 mg equivalent RP phenolics 100 g^?1 meat, respectively) and VC 50 (50 mg VC 100 g^?1 meat). The RP exhibited significantly (P < 0.05) higher reducing power and 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity. Incorporation of RP into chicken patties significantly (P < 0.05) reduced the HunterLab L* values compared with control and VC patties. Total phenolic content (as tannic acid equivalent) significantly (P < 0.05) increased from 308 in control to 441 μg g^?1 in RP 20 patties. Addition of RP to chicken patties did not affect any of the sensory attributes. The values of thiobarbituric acid reactive substances were significantly (P < 0.05) reduced from 1.530 in control patties to 0.135 mg malonaldehyde kg^?1 samples in RP patties. Pomegranate rind powder extract treatment (RP 10, RP 15 and RP 20) substantially inhibited (P < 0.05) lipid oxidation in cooked chicken patties to a much greater extent than VC treatment. Therefore, pomegranate rind powder can be utilized as an excellent natural antioxidant source.     

The effectiveness of ozone and acidulant treatments in extending the refrigerated shelf life of fresh-cut potatoes

Abstract: The objective of the study was to determine the effectiveness of acidulant dip treatments (with or without aqueous ozone) to reduce enzymatic browning and to extend the shelf life of fresh‐cut potato slices during refrigerated storage (4 °C) for 28 d. Potato slices subjected to aqueous ozone (2 ppm) had significantly (P≤ 0.05) higher L‐values and lower a‐values, but ozone did not appear to have any effect on aerobic plate counts (APCs) or polyphenol oxidase (PPO) activity. NatureSeal (NS) and sodium acid sulfate (SAS) were the most effective acidulant treatments in reducing browning (significantly [P≤ 0.05] higher L‐values, lower a‐values, and browning index values) regardless of ozone treatment. NS and SAS also had lower PPO activity compared to other treatments on days 0 and 28, and significantly (P≤ 0.05) lower APCs (≤2.00 log CFU/g) over refrigerated storage. Therefore, the SAS treatment was comparable to NS, a commercially available product, and showed promise as an effective antibrowning dip to reduce browning and spoilage in fresh‐cut potato products. Practical Application: A 1% SAS dip treatment which included 1% citric and 1% ascorbic acid was found to be an effective antibrowning dip for fresh‐cut potatoes along with NatureSeal®'s PS‐10, compared to other treatments. They were both effective in maintaining low microbial counts over refrigerated storage. Additionally, aqueous ozone washes (2 ppm) showed significant benefits to reduce browning; however, ozone did not affect microbial counts or PPO enzyme activity. Therefore, the SAS treatment could have potential use in the fruit and vegetable industry to reduce browning and spoilage in fresh‐cut potato products.     

Antioxidative and antimicrobial activities of shrimp chitosan on gilthead sea bream (Sparus aurata) during refrigerated storage

This study aims to determine the effects of chitosan obtained from Metapenaeus stebbingi shells on the shelf life of refrigerated gilthead sea bream. It was determined that 1% chitosan‐coated samples had the lowest thiobarbituric acid (TBA) (3.05 mg malondialdehyde (MDA) kg^?1) and free fatty acids (FFA) value (2.79% oleic acid), while the control group had the highest TBA (5.08 mg MDA kg^?1) and FFA value (6.13% oleic acid) on the 27th day of storage. In the last day of storage, TVB‐N was found higher in control group (25.62 mg 100 g^?1) than chitosan‐coated samples (14.57 mg 100 g^?1). Total viable count value of the control group exceeded maximum permissible limit on the 27th day of storage. However, it was lower than 7.0 log CFU/g in chitosan‐coated samples during the refrigerated storage. As a result of this study, it was determined that shelf life of refrigerated gilthead sea bream can be increased up to 27 days with chitosan.     

A Comparative Study of Natural Antimicrobial Delivery Systems for Microbial Safety and Quality of Fresh‐Cut Lettuce

Nanoencapsulation can provide a means to effectively deliver antimicrobial compounds and enhance the safety of fresh produce. However, to date there are no studies which directly compares how different nanoencapsulation systems affect fresh produce safety and quality. This study compared the effects on quality and safety of fresh‐cut lettuce treated with free and nanoencapsulated natural antimicrobial, cinnamon bark extract (CBE). A challenge study compared antimicrobial efficacy of 3 different nanoencapsulated CBE systems. The most effective antimicrobial treatment against Listeria monocytogenes was chitosan‐co‐poly‐N‐isopropylacrylamide (chitosan‐PNIPAAM) encapsulated CBE, with a reduction on bacterial load up to 2 log₁₀ CFU/g (P < 0.05) compared to the other encapsulation systems when fresh‐cut lettuce was stored at 5 °C and 10 °C for 15 d. Subsequently, chitosan‐PNIPAAM‐CBE nanoparticles (20, 40, and 80 mg/mL) were compared to a control and free CBE (400, 800, and 1600 μg/mL) for its effects on fresh‐cut lettuce quality over 15 d at 5 °C. By the 10th day, the most effective antimicrobial concentration was 80 mg/mL for chitosan‐PNIPAAM‐CBE, up to 2 log₁₀ CFU/g reduction (P < 0.05), compared with the other treatments. There was no significant difference between control and treated samples up to day 10 for the quality attributes evaluated. Chitosan‐PNIPAAM‐CBE nanoparticles effectively inhibited spoilage microorganisms’ growth and extended fresh‐cut lettuce shelf‐life. Overall, nanoencapsulation provided a method to effectively deliver essential oil and enhanced produce safety, while creating little to no detrimental quality changes on the fresh‐cut lettuce.     

Improving quality of fresh‐cut mango using polysaccharide‐based edible coatings

This study was aimed at evaluating the effect of coatings with alginate (AL), pectin (PE), carboxymethyl cellulose (CMC) or chitosan (CH) on microbial stability, physicochemical attributes, total phenolics and carotenoids content, antioxidant capacity and sensory properties of fresh‐cut mango during 14 days at 4 ± 1 °C. Coated fresh‐cut mango kept microbial counts below 6 logs CFU g^?1, being CH‐coated fresh‐cut mango those that exhibited the lowest microbial counts (1 log CFU g^?1) along entire storage. AL, PE and CMC coatings maintained yellow colour of fresh‐cut mango throughout storage. AL and CH coatings, which have different monomers in their chain, improved the content of antioxidant compounds in fresh‐cut mango as related to uncoated. AL‐coated fresh‐cut mangoes were the toughest, among those coated, during 14 days. The highest consumer acceptance was achieved in AL (90.2%) coated fresh‐cut mango. CH would be the most suitable coating to extend the quality of fresh‐cut mango throughout storage.     

Oxidative enzymes and functional quality of minimally processed grape berries sanitised with ozonated water

Thompson Seedless (TS) and Black (BS) grapes sanitised with 2, 4, 6, 8 mg L^?1 O₃ or NaOCl (100 mg L^?1) were stored 21 days at 5 °C. Ozonated water stimulated the respiration rate, especially after 5 days of storage, and increased superoxide dismutase and catalase activity compared to NaOCl‐sanitised grapes. Total polyphenol content (TPC) was 23–50% higher in TS and 18.5–28% higher in BS samples sanitised with ozonated water. Twofold higher total antioxidant capacity (TAC) was registered in TS at all of the evaluated O₃ doses while the doses of 6 and 8 mg L^?1 increased TAC by 19–30% in BS. The use of ozonated water as a sanitising method, especially at 6 and 8 mg L^?1 doses, improved the functional quality and maintained low microbial counts on fresh‐cut grapes being a good alternative for the industry.     

MODEL OF MICROBIAL GROWTH ON FRESH-CUT LETTUCE TREATED WITH CHLORINATED WATER DURING STORAGE UNDER DIFFERENT TEMPERATURES

Various Gompertz models of the growth of bacteria on fresh‐cut lettuce were established in order to predict the shelf life of fresh‐cut lettuce untreated and treated with chlorinated water in storage under different temperatures. The sensory quality of fresh‐cut lettuce treated with water containing 75 µg/L of available chlorine was also examined during storage at 0, 4 and 25C, respectively. Bacteria growth on fresh‐cut lettuce in storage was analyzed to evaluate the effect of temperature, and the established model of predictive bacteria growth on fresh‐cut lettuce fitted the Gompertz modified model best. The lag time λ, the asymptote A and maximum specific growth rate μ_m of the bacteria were calculated, according to Gompertz models. The value of μ_m and A at 0C were lower than that at 4 and 25C, and the lag time was longer at a low temperature than at a higher temperature, indicating that the lower the storage temperature, the slower the growth of bacteria on lettuce, and the smaller the maximum bacteria number reached on the lettuce. The efficacy of preservation of fresh‐cut lettuce treated with chlorinated water was significantly better than that of nontreated lettuce under the same storage temperature. It was found that the final bacteria number predicted (S) on lettuce treated with chlorinated water was lower than that on nontreated lettuce, and that the higher the storage temperature, the higher the final bacteria number predicted (S). The established growth models at different temperature were able to predict the shelf life of fresh‐cut lettuce.     

Effects of light exposure on chlorophyll,sugars and vitamin C content of fresh‐cut celery (Apium graveolens var. dulce) petioles

Effects of light exposure (24 μmol m^?2 s^?1) on fresh‐cut celery nutritional quality were evaluated during 8‐day storage at 7 °C using darkness as control. Light exposure preserved 47% chlorophyll a and 48% chlorophyll b contents more than darkness at the end of storage. Sucrose, reducing sugar and glucose contents in light‐stored petioles were 17%, 25% and 67% higher than those in dark‐stored petioles after 8‐day storage, respectively, thus resulting in higher total soluble solids content in light condition. Moreover, l ‐ascorbic acid content increased at 2‐day storage in light condition and was 46% more than in darkness at the end of storage. The fresh weight loss significantly increased in all petioles, and this increase was markedly accelerated by light exposure with a maximum of 1.43% at the end of storage. Dry matter content was induced more by light exposure than by darkness at 2‐day storage.     

Polyphenol oxidase activity in grass and its effect on plant‐mediated lipolysis and proteolysis of Dactylis glomerata (cocksfoot) in a simulated rumen environment

Little is known about the level or activity of polyphenol oxidase (PPO) in grasses and its potential impact on proteolysis and lipolysis. Six grass species were initially screened for PPO activity (740.6, 291.9, 213.6, 119.0, 16.3 and 6.5 U g^?1 fresh weight (FW) for cocksfoot, hybrid ryegrass, Italian ryegrass, perennial ryegrass, timothy and tall fescue respectively). Cocksfoot, which expressed the highest activity, was then used to determine the effect of PPO on plant‐mediated proteolysis and lipolysis in a simulated rumen environment. Sourced cocksfoot was macerated and incubated in an antibiotic‐containing anaerobic medium with or without ascorbate to deactivate PPO in the dark at 39 °C over five time points. At each time point (0, 1, 2, 6 and 24 h), six replicate samples were destructively harvested; three of the replicates were used for lipid analysis and the other three for protein, free amino acid and bound phenol determination. Characterisation of the herbage showed PPO activities of 649.6 and 0 U g^?1 FW, which were reflected in the extent of phenol (derived from quinones) binding to protein after 24 h of incubation, namely 65.1 and 29.6 mg bound phenol g^?1 protein (P < 0.001) for cocksfoot and cocksfoot + ascorbate respectively. Proteolysis, measured as free amino acids released into the incubation buffer, was significantly reduced (P < 0.001) with increasing PPO activity, with values after the 24 h incubation of 0.03 and 0.07 mmol L^?1 g^?1 FW for cocksfoot and cocksfoot + ascorbate respectively. Lipolysis, measured as the proportional decline in the membrane lipid polar fraction, was likewise reduced (P < 0.001) with increasing PPO activity, with values after the 24 h incubation of 0.43 and 0.65 for cocksfoot and cocksfoot + ascorbate respectively. Changes that occurred in protein and the lipid fractions (polar fraction, monoacylglycerol + diacylglycerol, triacylglycerol and free fatty acids) during the incubations are also reported and discussed. These results support the selection of forages high in PPO activity to reduce protein and lipid losses in silo and potentially in the rumen. Copyright © 2006 Society of Chemical Industry     

Effect of grape dietary fibre on the storage stability of innovative functional seafood products made from farmed meagre (Argyrosomus regius)

Two groups of farmed meagre (Argyrosomus regius) sausages were studied regarding quality changes and antioxidant capacity during a 98‐day storage experiment at 2 ± 2 °C. Control sausages contained 3.9% (w/w) of inner pea dietary fibre (IPDF) and the other group contained 0.9% (w/w) IPDF plus 3.0% (w/w) of antioxidant grape dietary fibre (AGDF). The control and AGDF meagre sausages presented a high nutritional value, given their low caloric content, fatty acid profile, amino acid composition and high DF content. Both products were remarkably stable over storage time. The AGDF had an effective antioxidant capacity, proven not only by the radical scavenging activity (90.0–91.0% vs. 82.1–85.4%) and reducing power (8.13–9.10 mg ascorbic acid equivalent g^‐1 vs. 4.16–4.24 mg ascorbic acid equivalent g^?1) measurements, but also by the lower thiobarbituric acid reactive species (TBARS) values (0.78–1.10 vs. 1.50–2.08 mg malonaldehyde kg^?1) over storage time. AGDF seemed to present antimicrobial effect, since on the 63rd day (beginning of significant microbial growth), the control sausages had more than 3 log CFU g^?1 and AGDF sausages much <3 log CFU g^?1. The sensory assessment pointed to some loss of textural quality, more accentuated in the AGDF sausages.     

Alginate-based coatings charged with hydroxyapatite and quercetin for fresh-cut papaya shelf life

In this study, the effect of alginate-based coatings charged with quercetin glycoside compounds and hydroxyapatite/quercetin glycoside compounds (HA/QUE) on the microbiological quality, and on bioactive compounds of fresh-cut papaya, was evaluated for 14 days at 6 °C. Alginate coatings with hydroxyapatite/quercetin showed a high capability to slow down the growth of all microbiological parameters investigated. At the end of cold storage, the total bacteria count in papaya samples covered with HA/QUE alginate coating was 4.8 log CFU g⁻¹ which is significantly lower (P < 0.05) than 8.3 log CFU g⁻¹ for uncoated samples. Total carotenoids’ percentage decrease, at the end of storage, was about 20% in papaya with active coatings, with respect to the losses of 39 and 35%, registered in uncoated and alginate-coated samples respectively. Vitamin C content and the antioxidant activity measured in papaya coated with HA/QUE alginate showed significantly higher values (P < 0.05) for each storage day than those detected for control- and alginate-coated samples. Based on the sensory evaluation, active-coated fresh-cut papaya reached, at the end of the storage period, suitable values for commercial purposes.     

From wheat sourdough to gluten‐free sourdough: a non‐conventional process for producing gluten‐free bread

Gluten‐free (GF) sourdough was prepared from wheat sourdough and analysed both in fresh (GFS) and dried forms (DGFS). The gluten content in each GF sourdough sample was <20 mg kg^?1. The dough leavening capacity and the properties of the bread samples were investigated and compared to those of bread prepared using bakery yeast (Saccharomyces cerevisiae). Two commercial rice‐based mixtures (different for the presence/absence of buckwheat flour) were used to prepare bread samples. In GFS, lactic acid bacteria (LAB) and yeasts were found in amounts corresponding to 10⁸ and 10⁷ CFU g^?1, respectively, whereas both LAB and yeasts were detected in lower amounts (about 10⁶ CFU g^?1) in DGFS. When used in bread‐making, both GFS types produced significant dough acidification and exhibited good dough development during proofing, resulting in loaves with specific volume values between 3.00 and 4.12 mL g^?1, values similar to those obtained for reference bread (3.05÷4.15 mL g^?1). The use of GFS was effective in lowering the bread staling rate during storage for up to 7 days.     

Lycopene content differs among red‐fleshed watermelon cultivars

Lycopene, a carotenoid, has antioxidant properties that may reduce the incidence of certain cancers. Watermelon (Citrullus lanatus (Thunb) Matsum & Nakai) is a natural source of lycopene, with a reported average content of 48.7 µg g^?1 fresh weight based on samples taken from retail produce. This study demonstrated the variability of lycopene content in 11 red‐fleshed watermelon cultivars grown at one location, representing seedless, open‐pollinated and hybrid types, and in commercially shipped hybrid and seedless melons, representing seasonal production periods. Tristimulus colorimeter a* and chroma values were positively correlated with lycopene values, but linear or quadratic regressions of colorimeter data against lycopene values were not significant. Tristimulus colorimeter readings from cut melons were compared to amounts of lycopene extracted from the same melons. Lycopene content varied widely among cultivars, with four cultivars having mean values greater than 65.0 µg g^?1 fresh weight. Seedless types sampled tended to have higher amounts of lycopene (>50.0 µg g^?1 fresh weight) than seeded types. Watermelon lycopene content changed for some cultivars with production season. Published in 2001 for SCI by John Wiley & Sons, Ltd