Archivio Pubblicazioni - 2013

11.09
2013

Determination of Soursop (Annona muricata L. cv. Elita) Fruit Volatiles during Ripening by Electronic Nose and Gas Chromatography Coupled to Mass Spectroscopy

Carlos Julio Márquez Cardozo; José Régulo Cartagena Valenzuela and Guillermo Antonio Correa Londoño

 

As an exotic highly perishable tropical fruit commercially grown in Colombia, soursop (Annona muricata L.) is currently in need of postharvest handling studies. Thus, the present research was conducted to characterize the volatile compounds of soursop cv. Elita during postharvest. For this purpose, fruit ripeness was evaluated, for one thing, by a volatile compound measuring system known as electronic nose (EN), and for another thing, by headspace solid phase microextraction and gas chromatography mass spectrometry (HS-SPME/GC-MS). The profile of volatile substances in fruits is one of the main indicators of the sensory attributes that typify the organoleptic quality of these products. The EN constitutes an economical, relatively simple, fast and innovative alternative to determine groups of volatile compounds in whole or fractionated samples from fruits of commercial interest. In contrast, and despite its being a highly selective technique, the use of SPME/CG-MS might be limited by its elevated cost. Based on EN assessment, fruit ripening stages were classified as unripe, half ripe, ripe and overripe. The most active EN sensors were numbers 2 sensitive to nitrogen oxides), 6 (sensitive to methane) and 8 (sensitive to alcohols and partially aromatic compounds). HS-SPME/GC-MS analysis allowed establishing that during postharvest, the major proportion of volatile compounds corresponded to esters, predominantly Methyl hexanoate. Particularly in overripe fruits, the presence of alcoholic compounds coincides with the EN assessment, which, for its part, detected mainly alcohols and a wide range of aromatic substances. The study contributes to the characterization of postharvest volatiles, which are one of the major sensory attributes of tropical fruits.

 

20.02
2013

Electronic nose evaluation of volatile emission of Chinese teas: from leaves to infusions

TORRI L., Rinaldi M., Chiavaro M. (in press). INTERNATIONAL JOURNAL OF FOOD SCIENCE AND TECHNOLOGY. DOI: 10.1111/ijfs.12429


An electronic nose can be used to discriminate tealeaf quality, but to the best of the author's knowledge, studies that address the changes in electronic sensor signals between tea leaves and infusions are not available. In this framework, this preliminary work compared the volatile emissions of leaf samples belonging to the basic Chinese teas (white, yellow, green, oolong, black and pu erh) with those of their respective infusions using an electronic nose. Different signal responses were qualitatively and quantitatively obtained from the sensors both for the tea leaves and their respective infusions, showing that the leaf aroma is not transferred as it is into the beverage. The teas were grouped according to the different fermentation techniques based on the percentage variations in the sensor contributions to the complete description of the volatile profiles. The results indicated that the electronic nose is a suitable tool to monitor the volatile emission differences that occur between leaves and infusions in different tea types

20.02
2013

Sensory test vs. electronic nose and/or image analysis of whole bread produced with old and modern wheat varieties adjuvanted by means of the mycorrhizal factor

TORRI L., Migliorini P., Masoero G. (2013) - FOOD RESEARCH INTERNATIONAL, vol. 54; p.1400-1408, ISSN: 0963-9969. 


In order to promote local organic farming and healthy local products, the germplasm of common wheat (Triticum aestivum spp.) retrieved from old-varieties (G — Gentil Rosso, I — Inallettabile, S — Sieve) has been compared with that of the modern Blasco Triticum, treated with (Bm — Blasco mycorrhizal) or without (B — Blasco) Micosat F® mycorrhizal consortium, and with that of an ordinary reference flour (C — Control). A sensory test (18 attributes, 10 panelists) was compared with rapid analyses: electronic nose (e-nose, 10 sensors, 8 replicates) and/or image analysis (9 parameters, 3 replicates). The planned contrasts were able to establish the significance of the epoch and of the mycorrhizal factors. Chemometrics of the e-nose, image and concatenated scores was used to cluster the average groups. The reference groups (B and C) were clearly distinguished. The mycorrhizal factor has emerged as being a botanical modifier of the sensory properties of the bread: a modern wheat treated with the Micosat F® microbial consortium after breading was established as non-differentiable from the old Sieve variety and to be similar to the old Gentil Rosso and Inallettabile varieties. The rapid analyses forecast several traits: the raw average cross-validated r-square, calculated across the 18 attributes, was 0.69 for the e-nose and 0.56 for the imaging features. However the concatenated sets rose to 0.83 and only 4 traits were below a 2.0 threshold of the ratio–performance prediction (RPD) while 10 scores exceeded 2.5 RPD.

01.01
2013

Evaluation of a portable MOS electronic nose to detect root rots in shade tree species

Manuela Baietto, Letizia Pozzi, Dan Wilson, Daniele Bassi; Computers and Electronics in Agriculture (Impact Factor: 1.77). 01/2013; 96:117-126. DOI: 10.1016

 

The early detection of wood decays in high-value standing trees is very important in urban areas because mitigating control measures must be implemented long before tree failures result in property damage or injuries to citizens. Adverse urban environments increase physiological stresses in trees, causing greater susceptibility to attacks by pathogenic decay fungi. The detection of fungal root rots in urban trees is particularly difficult because conventional detection tools, currently used for diagnosis of wood decays, are not feasible below ground level. Portable electronic olfactory systems or electronic noses (e-noses), currently used in many different scientific fields and industries, previously have been tested for the early diagnosis of wood decay fungi and wood rots. We evaluated the accuracy and effectiveness of the portable PEN3 electronic nose to discriminate between healthy and decayed root segments of five shade trees species, artificially inoculated separately with three species of root-rot fungi and incubated in different soil types under laboratory conditions. The PEN3 e-nose discriminated between healthy and inoculated root fragments and between different decay fungi in different soil types for most host-fungus combinations, but the discrimination power of this e-nose varied depending on tree species and strain of root-rot fungus analyzed. We provide explanations for the ineffectiveness of the e-nose to detect low levels of decay for certain host-fungus combinations. The advantages of e-nose detection over conventional wood decay detection tools also are discussed.