Improving the quality of apple purée.

The aim of the present study was to evaluate the effect of addition of 5% of apple peel powder (APP) and sugars (1, 5% of glucose, fructose, sucrose or trehalose) in apple purée on its phenolic composition and antioxidant activity (AOA). Apple purée samples were processed by freezing and freeze-drying. Apple purées containing APP showed higher phenolics, and AOA than the purées without APP. In freeze-dried samples the highest retention of individual polyphenols was achieved with addition of 1% of fructose or trehalose. However, in frozen samples the best impact on polyphenol retention had 5% of sucrose or trehalose. The results from this study showed the antioxidant potential of apple peel as a naturally-sourced antioxidants as well as a new insight into phenol-sugar interaction. These new findings could be of interest for the development of new food products rich in antioxidants which can improve human health.

Variability of 4-Monomethylsterols and 4,4'-Dimethylsterols in Olive Oil and Their Use as Indicators of Olive Variety, Ripening Degree, and Oil Storage Temperature.

To investigate the variability of 4-monomethylsterols and 4,4'-dimethylsterols in olive oil as a result of variety, ripening, and storage temperature, 36 samples were subjected to gas chromatography with flame ionization detection (GC-FID) and with mass spectrometric detection (GC-MS), and results were processed by univariate and multivariate statistics. Relative amounts (percent) of ß-amyrin, cycloartenol, and 24-methylenecycloartanol accounted for the most variation due to variety, while citrostadienol (percent) and 24-methylenecycloartanol (milligrams per 100 g) were strongly affected by ripening. Multivariate statistics differentiated olive oils regardless of storage conditions, which implied the possibility to use 4-monomethyl- and 4,4'-dimethylsterols as indicators of variety and ripening degree for fresh and stored oils. Absolute changes in 4-monomethyl- and 4,4'-dimethylsterols after storage were of a much smaller magnitude, meaning the investigated olive oils essentially retained health-beneficial features that derive from these compounds. Relative changes caused by storage were specific for each storage temperature and were useful in discriminating oils by linear discriminant analysis.

Effects of sugar addition on total polyphenol content and antioxidant activity of frozen and freeze-dried apple purée.

The objective of this study was to investigate the influence of simple sugar addition including (glucose, G; fructose, F; sucrose, S; and trehalose, T) on the total polyphenol content (TPC) and antioxidant activity (AOA) of apple purée processed by freezing and freeze-drying and stored for 6 months. The apple polyphenol profile was mostly preserved in the freeze-dried samples with sugar addition during 6 months of storage, whereas the polyphenol profile in frozen samples consists only of quercetin glycosides, of which rutin had the largest share. After 6 months, the highest level of polyphenols was detected in frozen 'Idared' and 'Fuji' apple purée with addition of T 5% (12.2 and 16.7 mg/100 g FW, respectively), whereas in freeze-dried apple purée the highest TPC was in 'Idared' and 'Fuji' with addition of T 1% (16.3 and 13.6 mg/100 g FW, respectively). Results indicate that sugar addition before processing could have potential for enhancing product quality.

Prevalence and level of Listeria monocytogenes and other Listeria sp. in ready-to-eat minimally processed and refrigerated vegetables.

Minimally processed and refrigerated vegetables can be contaminated with Listeria species bacteria including Listeria monocytogenes due to extensive handling during processing or by cross contamination from the processing environment. The objective of this study was to examine the microbiological quality of ready-to-eat minimally processed and refrigerated vegetables from supermarkets in Osijek, Croatia. 100 samples of ready-to-eat vegetables collected from different supermarkets in Osijek, Croatia, were analyzed for presence of Listeria species and Listeria monocytogenes. The collected samples were cut iceberg lettuces (24 samples), other leafy vegetables (11 samples), delicatessen salads (23 samples), cabbage salads (19 samples), salads from mixed (17 samples) and root vegetables (6 samples). Listeria species was found in 20 samples (20 %) and Listeria monocytogenes was detected in only 1 sample (1 %) of cut red cabbage (less than 100 CFU/g). According to Croatian and EU microbiological criteria these results are satisfactory. However, the presence of Listeria species and Listeria monocytogenes indicates poor hygiene quality. The study showed that these products are often improperly labeled, since 24 % of analyzed samples lacked information about shelf life, and 60 % of samples lacked information about storage conditions. With regard to these facts, cold chain abruption with extended use after expiration date is a probable scenario. Therefore, the microbiological risk for consumers of ready-to-eat minimally processed and refrigerated vegetables is not completely eliminated.

Sterols and triterpene diols in olive oil as indicators of variety and degree of ripening.

Sterols and triterpene diols in olive oil as indicators of variety and degree of ripening derived from three olive varieties and produced at three different harvesting periods were studied. In order to test the stability of the proposed indicators, oils obtained were stored for 12 months at three different temperatures. Thirty-six samples in total were subjected to GC analysis and results were processed by multivariate chemometric methods (MANOVA, PCA, and SLDA). Campesterol, ß-sitosterol, Δ(7)-campesterol/Δ(5,24)-stigmastadienol, clerosterol, uvaol, and campestanol/Δ(7)-avenasterol were established as the indicators of variety of fresh oils, while when stored oils were included in the model, the final three compounds were substituted by 24-methylene-cholesterol/stigmasterol. The most important variables for differentiating fresh oils according to degree of ripening were Δ(7)-campesterol/ß-sitosterol, uvaol/stigmasterol, clerosterol/Δ(5)-avenasterol and sitostanol/uvaol, while stored oils were differentiated by campestanol/stigmasterol, erythrodiol, stigmasterol/Δ(7)-campesterol, Δ(5)-avenasterol, 24-methylene-cholesterol/ß-sitosterol and 24-methylene-cholesterol. Results demonstrated that sterols and triterpene diols can be used as indicators of variety and degree of ripening among virgin olive oils.

Effect of trehalose addition on volatiles responsible for strawberry aroma.

Aroma is one of the most important quality properties of food products and has a great influence on quality and acceptability of foods. Since it is very difficult to control, in this study the effect of addition of trehalose (3, 5 and 10%) to freeze-dried strawberry cream fillings was investigated as a possible means for retention of some of the aroma compounds responsible for the strawberry aroma. In samples with added trehalose, higher amounts of fruity esters were determined. Increase of trehalose content did not cause a proportional increase in the amount of fruity esters. However, results of our research showed that trehalose addition did not have the same effect on both gamma-decalactone and furaneol.

Effect of hot water and hydrogen peroxide treatments on survival of salmonella and microbial quality of whole and fresh-cut cantaloupe.

Cantaloupe melon has been associated with outbreaks of salmonellosis. Contamination might be introduced into the flesh from the rind by cutting or by contact of cut pieces with contaminated rinds. Our objectives were to investigate the efficacy of hot water or hot 5% hydrogen peroxide treatments in reducing the population of native microflora and inoculated Salmonella on cantaloupe rind and transfer to fresh-cut tissue during cutting. Whole cantaloupes, inoculated with a cocktail of Salmonella serovars to give 4.6 log CFU/cm2 and stored at 5 or 20 degrees C for up to 5 days, were treated with hot water (70 or 97 degrees C) or 5% hydrogen peroxide (70 degrees C) for 1 min at 0, 1, 3, or 5 days postinoculation. Aerobic mesophilic bacteria and yeast and mold on treated whole melon and fresh-cut pieces were significantly (P < 0.05) reduced by all three treatments. Treatments with hot water (70 and 97 degrees C) caused a 2.0- and 3.4-log CFU/cm2 reduction of Salmonella on whole cantaloupe surfaces irrespective of days of postinoculation storage prior to treatment up to 5 days at 5 or 20 degrees C, respectively. Treatment with 5% hydrogen peroxide (70 degrees C) caused a 3.8-log CFU/cm2 reduction of Salmonella. Fresh-cut pieces prepared from untreated inoculated melons and those treated with 70 degrees C hot water were positive for Salmonella. However, fresh-cut pieces prepared from inoculated whole melon dipped in water (97 degrees C) or hydrogen peroxide (70 degrees C) for 60 s were negative for Salmonella, as determined by dilution plating onto agar medium, but were positive after enrichment at days 3 and 5 of storage at 5 degrees C. The ability to detect Salmonella in fresh-cut pieces was dependent on the initial level of inoculation. The results of this study indicate that the use of hot water (97 degrees C) or heated hydrogen peroxide to reduce the population of Salmonella on contaminated whole cantaloupes will enhance the microbial safety of the fresh-cut product.