Conference Paper

Determination of Freshness of Eggplant Using Some Physical Parameters

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Surface gloss, stiffness and density were considered to be the prime contributors to the freshness of eggplant fruit. The freshness index was defined as the ratio of product of relative spectral reflectance (surface gloss) and stiffness ratios to the density ratio. Surface gloss was measured in terms of relative spectral reflectance using a computerized spectral radiometer system while stiffness was determined as an initial slope of force deformation curve obtained on a uniaxial compression testing machine. Weight and volume for computing density of eggplant were determined by standard methods. These parameters were changed to consumers’ acceptable limit by storing the eggplants for different periods at 25±2°C temperature and 90±5 % relative humidity. Experiments were replicated 5-8 times and the average values were used to compute dimensionless ratios (values at any time divided by initial value) that were later used to determine the freshness index. Various forms of equations were tested for best fitting to the data. Freshness index of eggplant fruit decreased exponentially with storage period while it varied in form of power equation of weight and density ratios. It attained the lowest value (5.6 %) at acceptable limit of weight ratio of about 0.87. The best relationships between freshness index with weight and density ratios was found to be in form of power equation (correlation coefficient 0.99) while decrease in price of eggplant was seen linear (correlation 0.98) with computed freshness index by these equations. This showed that the developed freshness index might estimate the price of eggplants using these equations satisfactorily.

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... Eggplant (Solanum melongena L.) is a common vegetable available in retail outlets worldwide but has a very limited shelf life for freshness (1)(2)(3). It is also known as aubergine, guinea squash or brinjal and a good source of vitamins and minerals (particularly iron) making its total nutritional value comparable with tomato (4). ...
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The effects of active packaging on the surface stiffness, mass, volume, density and weight changes of fresh as well as stored eggplant were studied at 11 and 25°C for 10 days with active packaging material Type 1 and 2 and control. Mass, volume, and surface stiffness of eggplant decreased linearly throughout the storage period regardless of storage conditions; while the mass density showed a reverse trend in the case of 11°C storage. Reduction rate of mass, mass density and weight was observed minimum at 25°C storage temperature with active packaging Type 1. The weight of eggplant decreased at a higher rate in the initial 4 days compared to that in the later period of storage regardless of storage temperature and type of packaging.
The goal of this study was to develop prediction models to estimate the storage days of tomato. The transmittance spectral data measured on tomato were preprocessed through normalization, SNV, Savitzky-Golay, and Norris Gap and then were used to build the prediction models using partial least square (PLS) method. For the experiments, the tomato samples of different varieties were collected at different harvest time. The samples were taken right after harvest from the field and then were stored in a low-temperature storage room in which room temperature was maintained at . The transmittance spectral data of the tomato samples were measured at three-day intervals for 16 days. The performance of the prediction models was affected by the preprocessing techniques as well as the varieties and harvest time of the tomato. The best model was found when SNV was applied. The accuracy of the best model was 90.2%. It can be concluded that the transmittance spectra are useful information for predicting the period of storage of tomato.
Surface gloss and weight loss are two important parameters to judge the freshness of eggplant. Data were collected in order to develop some quick and reliable instrumental methods to determine these. Surface gloss and weight loss of eggplant stored for 0–96 h at 80–84% relative humidity and 20°C temperature were determined using a computerized spectral radiometer and a precision electronic balance, respectively. The surface gloss was quantified in terms of gloss index, and a relationship between weight and gloss index during storage of eggplant was established. Gloss index and weight both decreased quadratically with storage period. Major changes were observed in the first 48 h of storage. Weight and gloss index of eggplant during storage were found to be correlated linearly.
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