Analysis and characterization of extra virgin olive oils
Hosted by OSOS, contributed by Andrea Checchetti on 23/03/2018


Samples of extra virgin olive oils obtained from the olive trees of the territory of San Giovanni in Fiore (CS), Italy, and samples common brands of extra virgin olive oils sold on the national territory, have been analyzed according to EU regulation n. 61/2011 of the Commission of 24 January 2011.

The extra virgin oils examined were characterized by investigating their acidity, the number of peroxides, the rancidity, and the spectrophotometric parameters that provide useful elements for assessing the composition and the quality. Furthermore, the IR analysis provides useful data that help carry out quality control.

Analysis and characterisation of Extra – Virgin Olive Oils (EVO OILS)

The characterisation of olive oils in terms of cultivation variety, geographic origin, genuineness and quality is a matter of great interest for the local community of San Giovanni in Fiore (Calabria, Italy) where the school is located. It is also worth underlining how oil is an important resource for the perspectives of economical and commercial development of the countries of the Mediterranean. The peculiar features of an oil, determining its quality, depend on several factors, such as technological features (picking, crushing, kind of extraction, fluidification, mixing, filtering), agronomical (kind of plantation, cultivation practices, irrigation, fertilisation), genetical (cultivation variety of origin), environmental and climatic (terrain, climate), ecologic (altitude, light exposure), season or harvesting year.

The learning model chosen to design the present activity is Inquiry-Based Laboratory (ILAB), considered particularly suitable to enhance creativity in high school students, in accordance with the results of the study by I Rahmawati, H Sholichin, and M Arifin  [1]. Chemistry learning with ILAB requires a pre-designed worksheet to guide students during the activities. Students are required to solve a real-life problem, which in this case is to characterise and analyse extra virgin olive oils. The project has been designed combining CLIL methodology and Inquiry-based approach. The tasks and activities of the module focus on contents belonging to Non-Linguistic Subjects (Chemistry and Biochemistry), but at the same time aim at improving the students’ receptive and productive skills in English according to the descriptors of the Common European Framework of Reference.

Given the relevance of the topic and of the activities performed by the students in terms of field experience and concrete technical skills, the project is also meant to provide the students with important hints of reflection concerning their future perspectives of professional growth and career-related choices.

Table 1 shows the design of ILAB worksheet for this type of report.

ILAB Activity

Task

Activity

Purpose

  1. Problem identification

Quality control of extra virgin olive oils

Students are faced with a real-life problem. In this activity, the student must determine the main chemical-physical characteristics of extra virgin olive oils

Elicit ideas about acidity, oxidation reactions, pigments, rancidity.

  1. Formulating hypotheses

Chemical-physical characterization of extra virgin olive oils (EVOO)

Students are asked to explain

Case#1: What are the quality parameters that define the chemical-physical and organoleptic characteristics of olive oils and olive-pomace oils? Establish the methods for evaluating these characteristics.

Case#2: How do we classify oils according to the acidity measured?

Case#3: Why do high temperatures, exposure to light and oxygen damage the quality of olive oils?

Case#4: Why does a low number of peroxides not necessarily imply a high quality? What kind of analysis must be performed?

Case#5: Why is it important to perform the UV/Vis and FT-IR spectrophotometric analysis?

To determine which basic principles will be used and how they will be connected;

To make hypotheses on the effects of environmental factors on the quality of olive oils; to perform creative thinking skills;

To choose and practice the necessary technical procedures for each specific purpose;

To research and organise the parameters for the quality characterisation of oils;

 

  1. Design experiments
  1. Acid-base titration
  2. Redox titration
  3. Spectrometric Qualitative analysis

Students design experiments procedure

by determining control variables, independent variables and their own

dependent variables

Apply the principles and knowledge previously acquired to verify the hypotheses previously formulated.

  1. Collecting data

Titrations results

Spectroscopic data

Students collect data from their designed

experiment, as well as 

Information needed to test the hypothesis.

Practising volumetric analysis, determination of spectroscopic parameters

  1. Data analysis

Interpretation of data

Students organize and analyse the data,

Connect them to the hypothesis, make predictions, select which

findings are consistent with the information already possessed.

Developing and applying high-order thinking skills (analysing, evaluating, creating);

  1. Conclusion

Quality control of extra-virgin olive oil

Students describe and interpret the findings

obtained based on the results of the hypothesis

test.

Production of a written report with graphic representation of the findings.

 

PARTNERSHIPS INVOLVED IN THE PROJECT:

Table 2

Family

Families of the students provided home-produced olive oils

University

University of Calabria, Italy

Oil factory

Oil Factory Fratelli Portaro, Belvedere Spinello, Calabria, Italy

 

RESOURCES NEEDED:

Technical equipment for volumetric and rheological analysis, U.V. Vis. and FT - IR spectrophotometry; samples of olive oils (produced by Portaro Brothers Oil Factory), of different kinds and qualities; samples of home-produced oils from families of the students; internet access to provide the students with opportunities to search for and evaluate information about global oil production.

URL TO FIND FURTHER INFORMATION:        https://avanguardieducativedavincisgf.wordpress.com/

[1] I. Rahmawati, H. Sholichin and M Arifin, Inquiry-Based Laboratory Activities on Drugs Analysis for High School Chemistry Learning, IOP Conf. Series: Journal of Physics: Conf. Series 895 (2017) 012117.

Keywords: Extra virgin olive oils, UV/Vis spectroscopy, FT-IR spectroscopy, acidity
Learning Objectives: Knowledge of the production methods of organic olive oil, knowledge of the main chemical-physical characteristics of extra virgin olive oils
Rating: 5/5
Views: 431
Languages: English, Italian
Students age group: 15 - 18
Subject domain: Physical chemistry, Analytical Chemistry, Natural resources
# of students participating: 12
Published on: 05.06.2018

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