Maria Gabriella Di Serio

Isolation and preliminary characterization of Lactobacillus plantarum bacteriophages from table olive fermentation

Nine table olive fermentation brines were analysed to demonstrate the presence of lytic bacteriophages active against Lactobacillus plantarum strains. Five brines, out of the nine studied, were added to selected strains of L. plantarum as starter cultures, while the other four brines were left to ferment spontaneously. Turbidity tests with different host strains inoculated in growth medium with added filter-sterilized brines demonstrated the presence of phages able to lyse the sensitive strains. Phages were isolated from fermented brines and their presence was confirmed by scanning electron microscopy. A subsequent phage characterization based on host range, restriction analysis and protein profiles was performed. This study reported for the first time the isolation and characterization of L. plantarum phages from table olive fermentation. This demonstrated presence of lytic phages active against L. plantarum could represent a serious obstacle in the regular table olive fermentation process. For these reasons, the search for phage-resistant strains, to use as starter cultures, could be important to counteract the development of fermentation problems.

Long-Term Spreading of Olive Mill Wastewater on Olive Orchard: Effects on Olive Production, Oil Quality, and Soil Properties

ABSTRACT In Italy, the law no 574 of 1996 permits and regulates the disposal of olive mill wastewater (OMW), the liquid by-product obtained in oil mill when olive fruits are processed to extract virgin olive oil, by its controlled spreading on cultivated soil. With the aim to verify the long-term effects of the practice on olive production, oil quality, and physical–chemical and microbiological characteristics of soil, different amounts of OMW were spread in February, for 9 years consecutively, on soil cultivated with olive trees. The results obtained confirmed that the controlled spreading of OMW is not harmful for the plant production. On the contrary, OMW spread on olive grove is useful for the fertility of soil and the growth of microflora for the important supply of nitrogen (N), phosphorus (P), potassium (K), and, above all, of organic matter. The evaluated biological properties indicated that OMW spreading stimulates the growth of soil fungal and fungus-like communities and aerobic N2 fix micro-organisms. With regard to the oil quality, the data indicate that no significant differences were ascertained on the analyzed parameters.

Commercial extra virgin olive oils: Global Quality Index computation and pattern recognition by chemometrics

Purpose The purpose of this paper is to guide the choice of consumers, putting on the label an additional claim, which can provide more information on the sensory profile and the nutritional and preservation features of the marketed extra virgin olive oil. Design/methodology/approach In order to define the concept of global quality, the following parameters were considered: fruity, bitter, pungency, 1-penten-3-one, phenolic substances, tocopherols, peroxide value, free acidity, palmitic acid, stearic acid oleic acid linoleic acid, and the campesterol/stigmasterol ratio. The study was carried out on 143 commercial extra virgin olive oils. Findings The Global Quality Index was calculated as the square root of the sum of the squares of the individual local indices, according to three different algorithms. The computation obtained was recognised by chemometric analysis. Social implications A legislative amendment on the labelling could be proposed through an additional claim that safeguards the consumers on the health profile, inducing them to a more targeted purchase. Originality/value Three different global quality levels “excellent”, “good”, and “sufficient” have been determined. This clustering has also been recognised with a statistical approach. Since in the market, consumers can find extra virgin olive oils of different overall quality levels, it is possible to guide the choice of customers through an additional claim on the label, able to give more information on the sensory profile and the nutritional and preservation features of the product.