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Applied Economics (Econ 11)
University of San Agustin
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Influence of production and conservation conditions on some physical and chemical properties of blueberries. Agricultural Engineering International, 19(3), 170-176.
Influence of production and conservation conditions on some physical and
chemical properties of blueberries
Christophe F. Gonçalves, Raquel P. F. Guiné**, Fernando Gonçalves and Daniela V. T. A. Costa
CI&DETS/ESAV, Instituto Politécnico de Viseu, Campus Politécnico, 3504-510 Repeses, Viseu, Portugal.
Abstract: This work studied the effect of production mode (organic versus conventional) and storage conditions on some physical and chemical properties of blueberry from different cultivars, namely Duke, Bluecrop, and Ozarkblue. The physical properties evaluated were caliber, color and texture and the chemical characteristics analyzed were moisture content, total soluble solids and acidity. Furthermore, the effect of storage on these properties was also evaluated. The results showed that blueberries cultivar Duke was bigger, with a more intense coloration, and presented a harder and more elastic texture, when compared with the other cultivars at study. With respect to production mode, it was found that the blueberries produced in organic farming were not so acid or sweet, but had a more intense blue color. The storage conditions did not show an important influence on the chemical properties of blueberry, but influenced the both color and texture.
Keywords : blueberry, conservation, color, organic farming, texture
Citation: Gonçalves, C. F., Guiné, R. P. F., Gonçalves, F. Co sta, D. V. T. A. 2017. Influence of production and conservation conditions on some physical and chemical properties of blueberries. Agricultural Engineering International: CIGR Journal,? (?):?-?.
* Corresponding author: Raquel Guiné, Professor, Dep. Food Industry, ESAV, Quinta da Alagoa, Estrada de
Nelas, Ranhados, 3500-606 Viseu, Portugal. Email: raquelguine@esav.ipv. Tel: +351 232 446 641, Fax: +351 232 426 536.
1 Introduction
Vaccinium is a genus of terrestrial shrubs belonging to the family Ericaceae and holds approximately 450 species, from which the most relevant species include Cyanococcus , Oxycoccus , Vitis-Idaea , Myrtillus , and Vaccinium (Song and Hancock, 2012). Original from North America the blueberry has been consumed by man since the sixteenth century, documented, and is popularly known as longevity fruit. It is berry with a bluish color, which is quite small, being, however, much appreciated for its exotic flavor (Dourte et al., 2010; Hummel et al ., 2012).
Blueberry is considered as one of the richest sources of bioactive compounds, comparing to other fruits, and consequently has a positive effect in protecting against many disorders, and particularly degenerative diseases, like memory loss, cancer, heart disease, vision problems and ageing (Shi et al., 2008). Blueberry cultivation has suffered a marked expansion, mainly due to an increase in fruit demand, and stimulates the interest both of producers and researchers due to its beneficial health characteristics, which are keys for the choice of consumers. The area under blueberry cultivation has more than doubled in Florida during the last 10 years and the worldwide production of blueberries has increased 152% in the last two decades. Hence, in the last two decades, the worldwide area planted with blueberries has largely increased, also possibly due to the greater availability of genetic material, which has allowed the diversification of the geographical zones suitable for the cultivation of this crop (Retamales et al., 2015). It has been shown that yield is greater when the harvest is carried out with the fruit completely blue, i., at full maturation, instead of being harvested at an early ripening stage suitable for export. In fact, when the fruit is allowed to mature on the bush, its diameter and weight have increased (Lobos et al., 2014; Ribera et al., 2010). Conventional agriculture includes practices such as burning of crop residues, the reversal of topsoil, mobilization for weed control and preparation of the seedbed. These techniques promote soil compaction, erosion, increased carbon dioxide and contamination of waterways with sediment, fertilizers and pesticides. Conventional agriculture practices have led to environmental damage and degradation of ecosystems, which posed a serious threat to the quality of life of all living beings (Sandhu et al., 2010). Organic farming aims to introduce external elements in the agro system in order to avoid the indiscriminate use of pesticides, which are destabilizing factors of the ecosystem. Hence, in recent years, there has been a significant increase in consumer demand for foods produced in organic farming in opposition to conventional farming. On the basis of this aspects related to the quality of the food produced using less aggressive cultivation techniques and on the other hand greater awareness of the general public about environmental issues and care in preserving ecosystems are demand (Zielinska et al., 2015). No doubt that organic agriculture is very significant and constitutes a rapidly growing segment of the food supply chain (Tertuliano et al., 2012). Blueberries are commercialized in different ways and food preparations, apart from the fresh form. However, fresh fruits quickly deteriorate after they are picked and have a shelf life of less than two weeks at 0ºC and 90%-95% humidity after harvesting (Portuguese Standard NP-783, 1985). Hence the conservation is the utmost importance. According to their genotypes and postharvest lives, blueberry cultivars resent different postharvest lives. Abiotic factors, such as climatic conditions, agricultural cultivation, harvesting method, storage conditions, degree of
and the Brix graduation was measured using a refractometer (model 3T from Atago, Tokyo, Japan). Three replicates were made in all cases.
2 Color measurement
The color of blueberries was determined with a colorimeter (Chroma Meter - CR-400, Konica Minolta, Tokyo, Japan) in the CIE Lab color space, though the Cartesian coordinates L*, a* and b*. The L* axis represents Lightness and varies from 0 (corresponding to no lightness, i., absolute black), to 100 which is maximum lightness (i. absolute white). The other axes are represented by Chromatic coordinates a* and b* and they are at right angles to each other. The a* axis varies from green at one extremity (represented by -a) to red at the other (+a), whereas the b* axis varies from blue at one end (-b), to yellow (+b) at the other. Although in theory there are no extreme values of a* and b*, in practice they can be numbered from -128 to +127. For each sample were examined 55 blueberries.
2 Texture analysis
To determine the textural properties, 55 representative berries of each sample were randomly selected. The analyzes were performed with a texturometer (model TA Plus, from Stable Micro Systems, Godaming, Surrey, UK) with the following test conditions: pre-test speed = 1.
mms-1, test-speed = 1 mm s-1, post-test speed = 10 mm s-1, distance = 6 mm, trigger force = 0 mm and a load cell of 50 kg. The results were treated with Exponent software TEE (Stable Micro Systems) and from the obtained texture profile (Figure 1) was determined firmness (strength on the highest peak) and elasticity (distance at the highest point).
Figure 1 Texture profile analysis for blueberry.
3 Results and discussion
3 Biometric characteristics
The results showed that the mass of blueberries varied depending on the cultivar and production mode. At harvest, the berries from cultivar Ozarkblue were heavier than the other cultivars, and particularly when produced in conventional mode (Table 1). This trend for the products was lighter when produced in organic production was observed for the other two varieties studied, although the differences were less significant, particularly in Bluecrop, where the difference was minimal. When harvested, the blueberries of cultivar Duke had higher average caliber as compared to the other cultivars (Table 1) either in organic farming or conventional production mode. The cultivar that showed a lower average caliber was Bluecrop grown in conventional production. For variety Ozarkblue, blueberries in conventional production had a higher caliber. The average sizes of the berries obtained for Ozarkblue was 0 to 1 cm, which were values lower than the results of 1 cm obtained by Machado and Jesus (2012) for the same cultivar. However, the harvest blueberry gauge values obtained in cultivars were similar to values obtained by Sousa (2007) that ranged 1 to 2 cm.
Table 1 Biometric characteristics at harvest of the blueberries studied
Note: (1) Cultivar: Du=Duke, Bl=Bluecrop, Oz=Ozarkblue; Production mode: Co=conventional, Or=organic; Identical uppercase small letters refer to samples that do not differ according to cultivar for the same production mode (Post Hoc LSD Ficher Test, p < 0). Identical uppercase capital letters refer to samples that do not differ according to production mode, for the same cultivar (Post Hoc LSD Ficher Test, p < 0).
3 Chemical analysis
Table 2 showed the chemical properties of the blueberries at harvest. The moisture content was very similar for both production modes, with just slight variations between varieties. The value obtained for cultivar Bluecrop (around 75% corresponding to 25% of dry matter) was higher than that 16% dry matter reported by Skupien (2006). In the study of Kalt and McDonald (1996), dry matter values obtained for blueberry in fresh state were around 13%.
Table 3 Moisture, total soluble solids and acidity of the blueberries along storage
Sample (1)
DuCoRe DuCoTa DuOrRe OzCoRe OzOrRe
DuCoRe DuCoTa DuOrRe OzCoRe OzOrRe
DuCoRe DuCoTa DuOrRe OzCoRe OzOrRe Note: (1)Cultivar: Du=Duke, Bl=Bluecrop, Oz=Ozarkblue; Production mode: Co=conventional, Or=organic; Conservation: Re=refrigeration, Ta=ambient temperature. (2)DAH=days after harvest. Note: Identical uppercase small letters refer to samples that do not differ according to cultivar for the same production mode (Post Hoc LSD Ficher Test, p < 0). Identical uppercase capital letters refer to samples that do not differ according to production mode, for the same cultivar (Post Hoc LSD Ficher Test, p < 0). Identical uppercase Greek letters refer to samples that do not differ according to storage time, in the same line (Post Hoc LSD Ficher Test, p < 0).
3 Color
Table 4 presented the values for the color coordinate L*, lightness, at harvest and after seven and 14 days of storage. At harvest, samples Ozarkblue were less dark, with higher values of L* (around 40), while cultivars Duke and Bluecrop exhibited similar values of L* (around 35). Along storage, lightness tended to decrease slightly, indicating that the blueberries became darker. The values of L* obtained by Zheng et al_._ (2003) and Rocha (2009), ranged from 31 at harvesting to 28 after 30 days of storage, thus confirming a tendency for decrease along time.
Table 4 Variation of color coordinates (L, a and b*) of the blueberries along storage**
Sample (1)
DuCoRe DuCoTa DuOrRe BlCo BlOr OzCoRe OzOrRe
DuCoRe DuCoTa DuOrRe BlCo BlOr OzCoRe OzOrRe
DuCoRe DuCoTa DuOrRe BlCo BlOr OzCoRe OzOrRe Note: (1) Cultivar: Du=Duke, Bl=Bluecrop, Oz=Ozarkblue; Production mode: Co=conventional, Or=organic; Conservation: Re=refrigeration, Ta=ambient temperature. (2)DAH=days after harvest. Identical uppercase small letters refer to samples that do not differ according to cultivar for the same production mode (Post Hoc LSD Ficher Test, p < 0). Identical uppercase capital letters refer to samples that do not differ according to production mode, for the same cultivar (Post Hoc LSD Ficher Test, p < 0). Identical uppercase Greek letters refer to samples that do not differ according to storage time, in the same line (Post Hoc LSD Ficher Test, p < 0).
The color coordinate a* showed in the present case values were very close to zero, either positive or negative but around zero (Table 4), thus indicating that there was neither a predominance of green nor of red (i. it is positioned in the gray area, of undefined color). Because all values were very similar and the standard deviations were of the same magnitude of the value itself (as a consequence of having positive and negative values), no comparisons could be made among the cultivars or along drying, because the results were similar in all cases. In the
Table 5 Firmness and elasticity of the blueberries upon harvesting and along storage
Sample (1)
DuCoRe DuCoTa DuOrRe BlCo BlOr OzCoRe OzOrRe Sample (1) DuCoRe DuCoTa DuOrRe BlCo BlOr OzCoRe OzOrRe Note: (1)Cultivar: Du=Duke, Bl=Bluecrop, Oz=Ozarkblue; Production mode: Co=conventional, Or=organic; Conservation: Re=refrigeration, Ta=ambient temperature. (2)DAH=days after harvest. Identical uppercase small letters refer to samples that do not differ according to cultivar for the same production mode (Post Hoc LSD Ficher Test, p < 0). Identical uppercase capital letters refer to samples that do not differ according to production mode, for the same cultivar (Post Hoc LSD Ficher Test, p < 0). Identical uppercase Greek letters refer to samples that do not differ according to storage time, in the same line (Post Hoc LSD Ficher Test, p < 0).
4 Conclusions
This study allowed to conclude that the blueberries from cultivar Duke were on average bigger when compared with the other cultivars at study, and that they also had a more intense darker blue color. With respect to the textural parameters, the berries from cultivar Duke showed to be harder and more elastic. The cultivars that presented at harvest the highest quantity of sugars was cultivar Ozarkblue, which produced in conventional mode and for the same cultivar acidity showed a trend for decreasing along storage time, with the statistical differences. With respect to the production mode it concluded that the fruits produced in organic farming had lower acidity and also total soluble solids. However, they were bluish and less elastic when compared with those from conventional mode. The storage temperature (cold or room temperature) was not found to expressively influence the chemical properties of blueberry as confirmed by the results of the statistical tests, but, contrarily, influenced the physical properties in a way that the
blueberries stored under refrigeration had a statistically significant less intense color and a firmer, less elastic texture.
References
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Hummel, N. A., A. D. Attaway, E. D. Coneva, J. Braswell, W. O. Cline, D. Marshall, D. M. Ferrin, K. L. Machtmes, and H. Roy. 2012. Creating a community of practice for blueberries. International Journal of Fruit Science, 12(1-3): 350-359.
Kalt, W., and J. McDonald. 1996. Chemical composition of lowbush blueberry cultivars. American Society for Horticultural Science, 121(1): 142-146.
Lobos, G. A., P. Callow, and J. F. Hancock. 2014. The effect of delaying harvest date on fruit quality and storage of late highbush blueberry cultivars ( Vaccinium corymbosum L.). Postharvest Biology & Technology, 87(4): 133-139.
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Course: Applied Economics (Econ 11)
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