F. A. Al-Said

Colour Measurement and Analysis in Fresh and Processed Foods: A Review

Colour is an important quality attribute in the food and bioprocess industries, and it influences consumer’s choice and preferences. Food colour is governed by the chemical, biochemical, microbial and physical changes which occur during growth, maturation, postharvest handling and processing. Colour measurement of food products has been used as an indirect measure of other quality attributes such as flavour and contents of pigments because it is simpler, faster and correlates well with other physicochemical properties. This review discusses the techniques and procedures for the measurement and analysis of colour in food and other biomaterial materials. It focuses on the instrumental (objective) and visual (subjective) measurements for quantifying colour attributes and highlights the range of primary and derived objective colour indices used to characterise the maturity and quality of a wide range of food products and beverages. Different approaches applied to model food colour are described, including reaction mechanisms, response surface methodology and others based on probabilistic and non-isothermal kinetics. Colour is one of the most widely measured product quality attributes in postharvest handling and in the food processing research and industry. Apart from differences in instrumentation, colour measurements are often reported based on different colour indices even for the same product, making it difficult to compare results in the literature. There is a need for standardisation to improve the traceability and transferability of measurements. The correlation between colour and other sensory quality attributes is well established, but future prospects exist in the application of objective non-destructive colour measurement in predictive modelling of the nutritional quality of fresh and processed food products.

Modified atmosphere packaging technology of fresh and fresh-cut produce and the microbial consequences ? A review

Modified atmosphere packaging (MAP) technology offers the possibility to retard the respiration rate and extend the shelf life of fresh produce, and is increasingly used globally as value adding in the fresh and fresh-cut food industry. However, the outbreaks of foodborne diseases and emergence of resistant foodborne pathogens in MAP have heightened public interest on the effects of MAP technology on the survival and growth of pathogenic organisms. This paper critically reviews the effects of MAP on the microbiological safety of fresh or fresh-cut produce, including the role of innovative tools such as the use of pressurised inert/noble gases, predictive microbiology and intelligent packaging in the advancement of MAP safety. The integration of Hazard Analysis and Critical Control Points-based programs to ensure fresh food quality and microbial safety in packaging technology is highlighted.

Design of Packaging Vents for Cooling Fresh Horticultural Produce

This review focuses on the design of vents in packages used for handling horticulture produce. The studies on vent designs that are conducted to obtain fundamental understanding of the mechanisms by which different parameters affect the rate and homogeneity of the airflow and the cooling process are presented. Ventilated packages should be designed in such a way that they can provide a uniform airflow distribution and consequently uniform produce cooling. Total opening area and opening size and position show a significant effect on pressure drop, air distribution uniformity and cooling efficiency. Recent advances in measurement and mathematical modelling techniques have provided powerful tools to develop detailed investigations of local airflow rate and heat and mass transfer processes within complex packaging structures. The complexity of the physical structure of the packed systems and the biological variability of the produce make both experimental and model-based studies of transport processes challenging. In many of the available mathematical models, the packed structure is assumed as a porous medium; the limitations of the porous media approach are evident during vented package design studies principally when the container-to-produce dimension ratio is below a certain value. The complex and chaotic structure within horticultural produce ventilated packages during a forced-air precooling process complicates the numerical study of energy and mass transfer considering each individual produce. Future research efforts should be directed to detailed models of the vented package, the complex produce stacking within the package, as well as their interaction with adjacent produce, stacks and surrounding environment. For the validation of the numerical models, the development of better experimental techniques taking into account the complex packaging system is also very important.

Transpiration rate and quality of pomegranate arils as affected by storage conditions

This study investigated the transpiration rate (TR) of pomegranate (Punica granatum L.) arils under various combinations of temperature (5, 10 and 15°C) and relative humidity (RH) (76, 86 and 96%) during storage. Transpiration rateTR ranged from 1.14 to 16.75 g/kg day across the various combinations of RH and temperature studied. Relative humidityRH had the most significant impact on TR (p < 0.05). Transpiration rateTR increased six-fold when RH was reduced from 96 to 76%, and correlated well with water vapour pressure deficit (WVPD) (R 2 = 96.1%). Aril weight loss increased at higher WVPD. After 8 days of storage, losses in quality attributes of arils were higher with increasing storage temperature and lowering RH. A mathematical model to predict TR as a function of temperature and RH was developed and successfully validated at 8°C. The target water vapour transmission rate of packaging materials for pomegranate arils was found to be 33 to 68 g/m2 day.

Chemical composition and glycemic index of three varieties of Omani dates

The present study evaluated the nutritional quality and glycemic index of three sun-dried date varieties (Khalas, Khsab and Fardh) grown in Oman. Significant (P<0.05) differences were observed in the proximate chemical composition, dietary fiber contents, various sugar fractions and energy value of these dates. The moisture, ash, crude protein, total fat, and nitrogen-free extract values ranged between 18.77 and 23.71 g/100 g date flesh, 1.12 and 1.55 g/100 g date flesh, 1.28 and 1.89 g/100 g date flesh, 1.14 and 2.37 g/100 g date flesh, and 68.53 and 75.37 g/100 g date flesh, respectively. The dietary fiber and total sugar contents ranged between 8.83 and 13.11 g/100 g and between 52.17 and 59.96 g/100 g, respectively. The glycemic index (GI) of different varieties of dates collected from various regions of Oman ranged between 47.6 and 57.7. Overall no significant (P<0.05) differences were observed in the GI values of different varieties of dates. The regional effects on the GI values of dates were also non-significant (P>0.05). An inverse correlation (r2) was observed between the fructose fraction and the GI value of dates.

Salinity induced changes in vegetative and reproductive growth in tomato

Abstract Vegetative and reproductive growth were studied in five tomato (Lycopersicon esculentum Mill) cultivars under saline conditions imposed at the five‐leaf stage by addition of 50 mM NaCl to half strength Hoagland nutrient solution. The plants were raised in pots filled with washed quartz sand kept in a greenhouse. Stem height and number of leaves in tomato plants were significantly reduced when irrigated with saline regimes in contrast with control plants that received only the Hoagland solution. The highest number of flowers were obtained in the cultivar Pearson and the least in cultivar Strain B. Fruit set and yield were little affected by varietal differences and were not related to vegetative growth. Fruit weight was suppressed with NaCl stress, but improvement in weight was achieved when potassium (K) and calcium (Ca) were added to the saline water. The most detrimental effect of NaCl stress was the reduction of biomass yield in tomatoes. However, the relative dry weights of Pearson and Monte ...

Phytochemical content, antioxidant capacity and physicochemical properties of pomegranate grown in different microclimates in South Africa

We investigated the antioxidant and physicochemical properties of pomegranate (Punica granatum cv. Bhagwa) fruit grown in three microclimates in South Africa. The physicochemical properties of fruit peel and arils differed among the growing locations, including weight and redness color of both peel and arils. Contents of vitamin C, anthocyanin and total phenolics were 0.67–1.41 mg ml−1, 0.07–0.16 mg ml−1 and 8.54–13.91 mg ml−1, respectively. Fruit grown in locations with high light intensity had higher vitamin C content and lower phenolic content than those of fruit from low-altitude locations and high light intensity. The pH of juice did not significantly differ among locations, whereas significant variation was observed in total soluble solids (TSS), titratible acidity (TA) and TSS:TA ratio. Fruit from locations with low rainfall had high TSS and low TA. Principal component analysis was used successfully to classify fruit by growing location on the basis of antioxidant and phytochemical contents.

Fruit quality and partitioning of mineral elements in processing tomato in response to saline nutrients

Abstract A sand culture experiment was conducted to study the effect of saline water on the growth and fruit quality of processing tomato (Lycopersicon esculentum Mill.) Seedlings of five tomato cultivars were transplanted in quartz‐sand pots in a greenhouse at the Agricultural Experiment Station of Sultan Qaboos University. There were four saline nutrient solutions and a control consisting of half‐strength Hoagland solution. Salinity treatments were: 50 raM NaCl + 3 mM K2SO4 (EC 6.75), 50 mM NaCl + 1.5 mM orthophosphoric acid (EC = 7.18), 50 mM NaCl + 1.5 mM orthophosphoric acid + 3 mM R2SO4 (EC 7.29), and 50 mM NaCL (EC = 5.6). Treatments were applied daily commencing two weeks after transplanting. Data were collected on growth, and fruit yield and quality. Partitioning of mineral elements was determined in the vegetative tissue. The results obtained clearly show that concentrations of total soluble solids were increased in fruits treated with saline nutrients. Dry matter content of fruits exposed to sa...

Assessment of what the consumer values in fresh fruit quality: Case study of Oman

Abstract The health and nutritional benefits of fruit consumption are well documented in the scientific literature. Understanding consumer perceptions and attitudes towards fruit quality is important in setting quality specifications for marketing as well as providing a useful guide for postharvest research aimed at quality improvement of fresh produce. In this study, we investigated the frequency of fruit consumption and consumer perceptions of fruit quality in the Sultanate of Oman using self‐administered questionnaires. Results obtained showed that the frequency of fruit consumption was higher among males and families with high incomes. Banana was the most preferred fruit eaten by consumers whereas apple was the least preferred. Among the five types of fruit examined in the study, the most influential quality attributes affecting consumer purchase were flavour, sweetness, and colour for banana (Musa acuminata) and date (Phoenix dactylifera), and flavour, sweetness, and firmness for apple (Malus domestica), mango (Magnifera indica), and orange (Citrus sinensis). The most common fruit quality problems frequently observed by consumers in the market were fruit immaturity (banana), bruising (apple), rots/decay (mango and orange), and bad taste (date). A large majority of consumers (38%) expressed a willingness to pay up to 25% more on unit price for guaranteed good quality fruit; however, increasing price by more than 50% was highly unacceptable to 94% of consumers.

INFLUENCE OF CARBON/NITROGEN RATIO ON PYTHIUM APHANIDERMATUM AND ON PYTHIUM-INDUCED DAMPING-OFF OF RADISH

A study was conducted to investigate the effect of fertilizers with different carbon/nitrogen ratios (no carbon, NC; low carbon/nitrogen ratio, LC; high carbon/nitrogen ratio, HC) on Pythium aphanidermatum and on radish damping-off. The ratio of carbon to nitrogen applied in the field was 29, 22 and 0 in 2007 and 22, 17 and 0 in 2008 for HC, LC (as cattle manure) and NC, respectively. Field experiments over two growing seasons provided evidence for the lowest mortalities due to Pythium-induced radish damping-off to be in soil amended with LC (P 0.05), which may imply a lack of evidence for the effect of carbon/nitrogen ratio on reproduction in P. aphanidermatum.