Influence of olive paste preparation conditions on virgin olive oil triterpenic compounds at laboratory-scale

Hammer mill crushing variables and malaxation time are studied through a two‐level factor factorial experimental design in order to assess the impact of these parameters and their interactions on olive oil extraction efficiency, overall quality, and minor components composition. Extraction efficiency is mainly affected by the interaction between hammer mill grid size and malaxation time; higher yields are obtained when smaller grid sizes are combined with longer malaxation times. Regarding quality parameters and volatile compounds, the main effect is caused by malaxation time. Phenolic compounds are affected by all the studied parameters, hammer mill grid size has the highest impact on their final concentration in the oil. The results show that the effect of malaxation time on the studied variables is conditioned by the crushing parameters used during paste preparation. Practical Applications: Traditionally, the impact of processing variables on olive oil composition has been studied following a one‐variable‐at‐a‐time approach. A factor factorial experimental design allows the interactions among crushing conditions and malaxation time to be determined, as well as the individual contributions to extraction efficiency and minor components composition of these variables. Considering a more holistic approach to the study of olive oil extraction might provide processors with a wider spectrum of tools to maximize both yield and quality during olive oil processing. Interaction of grid size, rotor speed, and malaxation time during olive oil extraction affects extraction efficiency, volatiles, and phenolics.

Section: Resultsmentioning

confidence: 70%

Interactions Between Hammer Mill Crushing Variables and Malaxation Time During Continuous Olive Oil Extraction

Polari

Garcí-Aguirre

Olmo-García

et al. 2018

“…Hammer mill screen size (i.e., the diameter of the holes within the screen) and rotor speed have shown to have an impact on olive oil minor components, while causing no changes in quality indexes. Increments in rotor speed increased yield, chlorophylls, total phenols, secoiridoids derivatives, and triterpenic compounds, both in trials performed at laboratory and industrial scale. For the impact of screen size, previous publications indicate that a smaller screen size produce higher yields and oils with higher concentration of chlorophylls, total phenols, and secoiridoids derivatives .…”

Section: Introductionmentioning

confidence: 95%

Hammer Mill Sieve Design Impacts Olive Oil Minor Component Composition

Polari

Wang

2019

Crushing of the olive fruit is the first operation for olive oil extraction. The hammer mill is one of the most popular devices used in modern facilities due to its easy maintenance and high product output. The effect of hammer mill rotor speed and sieve design, including screen size and screen open area on extraction yield, overall quality and minor component composition, is evaluated at the laboratory scale. Quality parameters such as free fatty acids (FFA), peroxide value (PV), and UV absorbances (K232, K270, and ΔK) are unaltered by crushing parameters. Extraction efficiency, chlorophylls content, total phenol content, 3,4‐DHPEA‐EDA, and p‐HPEA‐EDA increase with faster hammer mill rotor speed and smaller screen size. Volatiles (E)‐2‐hexenal, hexanal, 1,5‐hexadiene‐(3,4)‐diethyl, 3‐ethyl‐1,5‐octadiene, and (E)‐2‐hexenol are only affected by screen size. Screen open area is found to be a relevant factor regarding extraction efficiency, chlorophylls, total, and individual phenols as well as the volatile compounds 1,5‐hexadiene (3,4)‐diethyl, 3‐ethyl‐1,5‐octadiene, hexanal, and (E)‐2‐hexenal. Practical Application: It is found that screen open area is a relevant factor regarding extraction efficiency, chlorophylls, total and individual phenols and volatile compounds, in addition to the screen size and rotor speed. This is useful information for millers who are interested in optimizing extraction efficiency as well as the minor compounds of extra virgin olive oil. Hammer mill sieve design impacts extraction efficiency, chlorophylls, total and individual phenols, and the volatile compounds during laboratory‐scale extraction of olive oil.

“…For these reasons, many studies have been performed to optimize each operation of the olive oil extraction process. Many investigations have been performed to determine the influence of technological operations of olive processing (i.e., crushing and malaxation) on olive oil yields and quality [1][2][3][4][5][6]. Recent research has been conducted on decanters to determine the best machine parameters to maximize extraction efficiency [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Machining effects of different mechanical crushers on pit particle size and oil drop distribution in olive paste

Leone

Romaniello

Zagaria

et al. 2015

The purpose of this study is to evaluate the effects of the mechanical components of the crushers on pits and oil droplet fractionation. The olive pastes obtained using four different crushing systems were compared. Analyses of the pit particle size distribution and oil drop aggregation were performed. The analysis of the experimental data shows that different crushing machines produce different pit and oil drop fragmentation, and the trends confirm that increased pit fragmentation corresponds to increased droplet fragmentation. Therefore, the results confirm that the partial de‐pitter and hammer crusher yielded the greatest enhancement in emulsification of oil droplets, and the stone mill and disc crusher yielded the greatest aggregation of oil droplets. Practical applications: The practical application of this work includes understanding the effects of four different crushers on oil drops and pit fragmentation. The experimental data could be useful to define the best malaxation time and to gain a better understanding of the minor components distribution in olive oil. The results obtained could be used to construct a guideline for the design and sizing of crushing machines. Different crushing machines produce different pit and oil drop fragmentation, and the trends confirm that increased pit fragmentation corresponds to increased droplet fragmentation. The data expressed in this research could be used to construct a guideline for the design and sizing of crushing machines with the goal of achieving a balance between pulp fragmentation, pit breakage and oil drop fragmentation.