Relationship Between Texture Sensory Profiles and Optical Properties Measured by Time-Resolved Reflectance Spectroscopy During Post-Storage Shelf Life of ‘Braeburn’ Apples

Abstract

Abstract‘Braeburn’ apples from three harvests after 6-month storage in controlled atmosphere were measured at 670 nm by time-resolved reflectance spectroscopy (TRS), ranked on decreasing μa670 (increasing maturity), classified as less (LeM), medium and more mature (MoM), randomised into three batches per harvest and analysed after 1, 8 and 14 days of shelf life. LeM and MoM apples were measured in the 630-900 nm range by TRS, and analysed for sensory profile (firm, crispy, juicy, mealy) and pulp mechanical characteristics (firmness, stiffness, energy-to-rupture). All data were processed by Principal Component Analysis (PCA). According to sensory intensity scores, fruits were either divided into five classes (very low – VL; low – L; medium – M; high – H; very high – VH) separately for every attribute, or clustered into four groups, each one representing a specific sensory profile. The absorption spectra showed a maximum at 670 nm (chlorophyll-a) and μa670 was higher in the VH class for firm, crispy and juicy and in the VL and L classes for mealy. The scattering spectra had a decreasing trend with the wavelength increase, and μs’ values were lower in the VH class for firm and crispy, and higher in the VH class for mealy and in the VL ones for juicy. PCA underlined that μs’ values were negatively related to firmness and μa670, and that μa690, μa730, μa830, μa850 and μa900 were opposed to mealiness. PC scores differed among the four sensory profiles and increased from VL to VH classes for firmness, crispiness and juiciness and from VH to VL classes for mealiness.

Time- and spatially-resolved spectroscopy to determine the bulk optical properties of ‘Braeburn’ apples after ripening in shelf life

“…In our work, we found that µ′ sTRS , and µ′ sSRS to a lesser extent, were negatively related to mechanical and acoustic parameters, in agreement with Rizzolo et al (2010Rizzolo et al ( , 2014 and Vanoli et al (2010Vanoli et al ( , 2015Vanoli et al ( , 2018 for µ′ sTRS . During the shelf life period, 'Braeburn' apples softened as firmness significantly decreased.…”

“…During the shelf life period, 'Braeburn' apples probably became mealy, as acoustic parameters also significantly decreased together with a dramatic increase of RISV: high values of mechanical and acoustic parameters accompanied with low RISV are characteristic of firm, crispy and juicy apples, while low values of mechanical and acoustic parameters with high RISV are typical of mealy apples, as found for 'Kanzi' and 'Braeburn' apples, respectively, by Vanoli et al (2018). Thus, the increase of µ′ sTRS observed in the present work could be due to the change of flesh texture from firm, crispy and juicy at harvest to mealy at the end of shelf life, as observed by Rizzolo et al (2014Rizzolo et al ( , 2019. In addition, Rizzolo et al (2010Rizzolo et al ( , 2014 and Vanoli et al (2010Vanoli et al ( , 2015Vanoli et al ( , 2018 found that µ′ sTRS was inversely related to sensory firmness, crispness and juiciness and positively related to mealiness and RISV.…”

“…In apples, µ a 670 decreased during fruit growth (Seifert et al, 2014) and ripening (Vanoli et al, 2005(Vanoli et al, , 2015Rizzolo et al, 2010;Zanella et al, 2013) as well as during cold storage (Vanoli et al, 2011(Vanoli et al, , 2015, more in air than in controlled atmosphere (Rizzolo et al, 2010), and during shelf life (Zanella et al, 2013). Less ripe apples (high µ a 670 values) showed a firm and crispy texture, while fruit having low µ a 670 values (riper) were softer and often showed a mealy texture (Rizzolo et al, 2014;Vanoli et al, 2005Vanoli et al, , 2015.…”

“…As for scattering, the µ′ s changed with advancing maturity and during storage depending on the apple cultivars and allowed apples with different texture characteristics to be distinguished (Rizzolo et al, 2014Rizzolo and Vanoli, 2016).…”

An integrated fiber-optic probe combined with support vector regression for fast estimation of optical properties of turbid media

“…The absorption coefficient m a may be related with components or chromophores of samples, and the reduced scattering coefficient m 0 s provides microstructure information [10]. Several methods for optical properties estimation have been reported, including time resolved method, frequency domain method and spatially resolved method [11,12]. However, both time resolved and frequency domain methods require expensive instruments which limits their applications.…”