Effects of olive leaf extract addition on fermentative and oxidative processes of table olives and their nutritional properties.

An experimental investigation evaluated the possibility of increasing the nutritional value of fermented table olives by adding olive leaf extract (OLE). OLE was added to table olives fermented using indigenous bacteria and yeasts, and a commercial starter (Lactobacillus plantarum strain). Microbiological, physico-chemical, and sensory analyses showed that OLE addition resulted in fermented olives with higher levels of antioxidant, anti-inflammatory, and antimicrobial substances, but did not adversely affect their qualities. Moreover, OLE and the commercial starter functioned synergically against spoilage microorganisms. In addition, fermented olives had higher values of hardness, total phenols, antioxidant activity, hydroxytyrosol, and verbascoside. Nonanal and ethanol contents were lower in fermented olives when Lactobacillus plantarum and OLE were used, indicating lower degrees of oxidation and fermentation. Finally, olives fermented with OLE had a less bitter taste.

Use of olive leaf extract to reduce lipid oxidation of baked snacks.

Olive leaves are a waste of the olive oil processing industry and represent a good source of phenolic compounds. The aim of this work was to assess the influence of olive leaf extract (OLE) on lipid oxidation of baked snacks, like breadsticks, made with wheat flour, extra virgin olive oil (EVO), white wine, and salt. Two EVOs having different peroxide value and antioxidant profile (total phenol content, tocopherols, carotenoids, and antioxidant activity) were considered. The snacks were subjected to oven test or stored in the usual conditions of retailer shelves. The obtained data highlighted that EVO plays a key role both for the quality and for the shelf-life of baked snacks and the use of OLE is recommended especially when baked snacks are produced with low quality EVO which therefore does not have a good content of natural antioxidants. The OLE addition significantly reduced the forced oxidative degradation during oven test, as evidenced by a decrease of 27% in oxidation-related volatile compounds and of 42% in triacylglycerol oligopolymers compared to control snacks (CTR) without OLE. Moreover, OLE effectively acted also in normal storage conditions, improving sensory data, induction times, antioxidant activity, and volatile compounds compared to CTR (i.e. hexanal 165.49 vs 38.31 µg g-1 in OLE-added). The amount of oxidation-related volatile compounds showed an opposite trend with the quality level of oil used.

Evolution of the oxidative stability, bio-active compounds and color characteristics of non-thermally treated vegetable pâtés during frozen storage.

BACKGROUND: Few studies have investigated the effects of frozen storage on processed vegetables. The present study evaluates its effects on the quality characteristics of non-thermally stabilized tomato-based pâtés compared to thermally stabilized pâtés stored at room temperature. Two different types of tomato-based pâtés were analyzed in terms of bio-active compounds, as well as colorimetric parameters and oxidative degradation just after processing and also after 4, 8 and 12 months of storage. RESULTS: Thermal treatment mainly affected the colorimetric parameters and oxidative degradation, whereas its effects on bio-active compounds became more visible and significant during storage. Freezing allowed in both pâtés to maintain significantly higher a* values than storage at room temperature, whereas brightness, which is linked to residual activities of different enzymes, varied during storage according to the ingredient formulation. During storage, oxidative degradation of the lipid fraction was more marked in the pâté containing a lower quality oil, and less marked when the absence of thermal treatment was combined with frozen storage. CONCLUSION: Freezing could represent a viable alternative way to preserve high-quality products over time. An optimal combination of blanching, freezing rate, storage and thawing conditions will provide the best results in terms of the quality/price ratio. © 2017 Society of Chemical Industry.

Microbiota and metabolome of un-started and started Greek-type fermentation of Bella di Cerignola table olives.

This study aimed to utilize an "omics" approach to evaluate the ability of selected lactobacilli and yeasts to improve the fermentation process of Bella di Cerignola table olives. Four types of fermentations were performed at the pilot-plant scale: un-started fermented olives used as a control (Ctrl); olives started with a commercial Lactobacillus plantarum strain (S); commercial L. plantarum strain and autochthonous yeast Wickeramomyces anomalus DiSSPA73 (SY); and L. plantarum, W. anomalus DiSSPA73, autochthonous L. plantarum DiSSPA1A7 and Lactobacillus pentosus DiSSPA7 (SYL). Compared to Ctrl, S, SY, SYL showed a higher acidification (P < 0.05) of the brine, which reached a pH value of 4.49 after one day of fermentation. The microbiota of unfermented olives and brine after one day of fermentation was primarily composed of Enterobacteria that belonged to Hafnia alvei and Methylobacterium. However, L. plantarum and L. pentosus dominated the total and metabolically active microbiota of the Ctrl brines and olives at the end of the fermentation. The use of lactobacilli and W. anomalus DiSSPA73 as a starter culture markedly affected the microbiota of the brines after one day of fermentation. The number of species (OTU) and the results of an alpha diversity analysis indicated that the microbial diversity of the brines was markedly simplified by the S, SY and, in particular, SYL fermentations. According to the lowest biodiversity, S, SY and SYL samples showed the lowest abundance of Proteobacteria, including Enterobacteriacea, Lactococcus lactis, Propionibacterium acidipropionici and Clostridium. The lactobacilli and W. anomalus DiSSPA73 used in this study markedly affected the amounts of free amino acids, phenolic and volatile organic compounds. Both a texture profile analysis and a sensory evaluation showed the highest appreciation for all of the started table olives. As shown through microbiological, biochemical, and sensory analyses, an accelerated fermentation of Bella di Cerignola table olives was achieved using the selected lactobacilli and yeast strains.

Influence of the thermal stabilization process on the volatile profile of canned tomato-based food.

The literature contains several papers dealing with the volatile constituents contributing to the aroma of fresh and processed tomatoes. Along with the traditional tomato-based products, tomato-based pâtés, characterized by complex ingredient formulations, are commonly consumed as a seasoning for pasta, and as a dressing for meats, salads, and sandwiches. To the best of our knowledge, no investigations have been published on the influence of thermal stabilization treatments on the composition of volatile compounds in tomato-based pâtés. To this aim, thermally stabilized and not stabilized tomato-based pâtés were subjected to the analysis of volatile compounds. The results obtained highlighted the influence of the thermal stabilization process on the evolution of volatile composition tomato-based pâtés. In particular, the terpenic compounds showed significant decreases after the thermal stabilization process treatment, due to their degradation and oxidation favored by high temperatures. The thermal stabilization caused, moreover, an increase in volatile compounds deriving from lipid oxidation and Maillard reaction, characterized by low-sensory thresholds, and from the thermal degradation of carotenoids and fresh tomato-derived compounds.