Thierry Tran

LCA applied to perennial cropping systems: a review focused on the farm stage

PurposePerennial crops globally provide a lot of fruit and other food products. They may also provide feedstock for bioenergy and have been, notably to this end, the subject of several LCA-based studies mostly focusing on energy and GHG balances. The purpose of this review was to investigate the relevance of LCAs on perennial crops, especially focusing on how the perennial crop specificities were accounted for in the farm stage modelling.MethodsMore than 100 papers were reviewed covering 14 products from perennial crops: apple, banana (managed over several years), orange and other citrus fruits, cocoa, coconut, coffee, grape fruit, Jatropha oil, kiwi fruit, palm oil, olive, pear and sugarcane. These papers were classified into three categories according to the comprehensiveness of the LCA study and depending on whether they were peer-reviewed or not. An in-depth analysis of the goal and scope, data origin for farming systems, modelling approach for the perennial cropping systems and methods and data for field emissions helped reveal the more critical issues and design some key recommendations to account better for perennial cropping systems in LCA.Results and discussionIn the vast majority of the reviewed papers, very little attention was paid on integrating the perennial cropping cycle in the LCA. It is especially true for bioenergy LCA-based studies that often mostly focused on the industrial transformation without detailing the agricultural raw material production, although it might contribute to a large extent to the studied impacts. Some key parameters, such as the length of the crop cycle, the immature and unproductive phase or the biannual yield alternance, were mostly not accounted for. Moreover, the lack of conceptual modelling of the perennial cycle was not balanced by any attempt to represent the temporal variability of the system with a comprehensive inventory of crop managements and field emissions over several years.ConclusionsAccording to the reviewed papers and complementary references, we identified the gaps in current LCA of perennial cropping systems and proposed a road map for scientific researches to help fill-in the knowledge-based gaps. We also made some methodological recommendations in order to account better for the perennial cycle within LCA considering the aim of the study and data availability.

Some properties of starch and starch edible films from under-utilized roots and tubers from the Venezuelan Amazons

Biopolymers from agricultural starchy commodities can be raw materials for edible, biologically degradable plastics. They have promising uses, having been proposed for replacing synthetic films. There are several starchy sources not yet quite exploited such as tropical roots and tubers that could be excellent starch sources to produce edible films with distinctive functional properties. The objective of this study was to formulate edible films from six tropical starchy crops. Starches were extracted and purified to 97–99% purity from Ipomoea batatas, Arracacia xanthorriza roots, Colocasia esculenta, Xanthosoma sagittifolium corms, and Dioscorea trifida tubers (white and purple) cultivated in the Venezuelan Amazons. The non-conventional starches were characterized for purity, amylose content and gelatinization profile by differential scanning calorimetry, starch granular morphometry and rheological properties. Starch-based films were processed by casting solutions prepared with each starch, glycerol, and distilled water. Starch suspensions were gelatinized by heat, degassed, poured in plates and dried. In the films, studies performed were water vapor, oxygen and carbon dioxide permeability, and mechanical properties in terms of tensile strength. Crystallinity patterns of native starches and films were also obtained. Ipomoea batatas and Colocasia esculenta exhibited polymorphism A+B type X-ray pattern, Xanthosoma sagittifolium, an A-type X-ray pattern, and Arracacia xanthorriza and both Diosocrea trifida, B-type patterns; while starch-based films had all a B-type X-ray pattern. As expected, the potential for these types of films are more in the area of decreasing gas exchange rather than retardation of water loss due to their hydrophilic nature. Films from these non-conventional starch sources with barrier and mechanical characteristics tailored for specific uses can be of interest as plastics for the food industry and results may be of significance also, for starch-based foams.

Combined effect of fermentation, sun-drying and genotype on breadmaking ability of sour cassava starch.

The influence of genotype and post-harvest treatments on expansion ability of sour cassava starch was investigated using 13 cassava genotypes from Colombia. Starches from cassava grown at 1000 m and 1700 m.a.s.l (3 lowland and 10 highland clones respectively) were modified by fermentation (0 or 30 days) and drying (oven or sun) treatments. RVA average peak viscosity decreased regularly from 952 cP in native starch to 699 cP in fermented and sun-dried starch. Granule size analysis revealed that fermentation hydrolysed lowland and highland granules by exocorrosion and endocorrosion respectively. This result was corroborated by significantly higher RVA breakdown and lower intrinsic viscosity in highland clones, reflecting different sensitivity to fermentation. For the first time, amylose contents ranging from 15.7 to 21.7% were correlated with expansion ability (3.0-8.6 mL/g) of sour cassava starch. Therefore the combination of cassava genotypes (mainly amylose content) and post-harvest treatments is key for expansion ability. Supra-molecular granule structure influenced sensitivity to fermentation.

Pneumatic drying of cassava starch: Numerical analysis and guidelines for the design of efficient small-scale dryers

ABSTRACT In a number of tropical countries, the expansion of cassava processing is tied to the development of small-scale, energy-efficient pneumatic dryers used to dry flour and starch. To facilitate this development, in this study a model of the pneumatic drying of starch particles was developed, to be fitted to measurements taken from large cassava processing factories. After that, numerical simulations were performed to analyze the effects of geometry and operating conditions on the energy efficiency and pipe length required to dry the product. The results clarified the influence of processing capacity, air inlet conditions, and starch particle size, emphasizing that air velocity as well as the dilution of the starch should be minimized. In light of the findings described here, we offer guidelines for the design of efficient small-capacity flash dryers.

Starch gelatinization and in vitro digestibility behaviour after heat treatment: Comparison between plantain paste and piece of pulp.

Over the 65-100°C range and at a water content of 1.6kgkg(-1)db, a comparison was conducted between plantain paste (dispersion made of flour and water) and pulp pieces after cooking to evaluate their respective degree of starch gelatinization (α) and in vitro digestibility. Below 76°C and at 100°C, the gelatinization behaviour of starch into pulp pieces and paste was similar, whereas at 85°C a significant mean relative difference was observed in between. For α in the 0-1 range, pieces of plantain pulp exhibited a lower rapidly digestible starch fraction (30%) and a higher resistant starch fraction (33%) than the flour paste, suggesting some structural effects. Both Weibull and exponential models showed a good fit for α over temperature range and starch digestibility fractions over α. Although no explicit relationship was established between the intact pulp structure and grinded flour state of plantain, the evaluation of the degree of starch gelatinization and digestibility of a plantain flour paste, could be used to predict the gelatinization and digestibility behaviour of plantain starch in entire pieces of pulp.

Development of a Novel Integrated Approach to Monitor Processing of Cassava Roots into Gari: Macroscopic and Microscopic Scales

Gari is a key staple food in several western African countries. This is a cassava traditional semolina obtained after peeling, rasping, fermentation, pressing, sieving, and roasting (cooking/drying). The process of gari production is artisanal and relies on human know-how, and the final properties of gari are highly dependent on the human skills. So as to understand the combined effect of the various transformation steps on the final quality of gari, the main objective of this work was to develop a lab-scale integrated approach to follow the transformation of the product characteristics during the process using macroscopic (water content, solid volume fraction, and particles size) and microscopic (physicochemical and biochemical) responses. At the microscopic level, pressing is a key step insofar as it induces the draining of many soluble compounds (especially the toxic cyanogenic compounds). At the macroscopic level, despite the strong similarity in median diameters of the intermediate and final products, two distinct agglomeration mechanisms occurred during the pressing/sieving and the roasting. These mechanisms highlight the structuration of the product at two different scales and at two different moments. Finally, results showed a high swelling capacity for fermented gari. The approach developed in this work will make it possible to identify the robust mechanisms, i.e., those little affected by a change in scale or in operating conditions. This identification will thereafter allow to distinguish unit operations, fairly easy to mechanize, from those requiring strict control to achieve the final product quality sought.

Life Cycle Assessment to Understand Agriculture-Climate Change Linkages

As one of the most comprehensive environmental assessment methodologies, life cycle assessment enables evaluation of the environmental impacts of anthropogenic activities along a supply chain. Its implementation raises many scientific questions. In the case of tropical cropping systems, researchers are working to understand and model environmental emissions based on the diversity of environments and systems. They are also focusing on the relationship between emissions and impacts. Cropping system life cycle assessments show that the impact on climate change varies by crop, environment and type of practice. Life cycle assessment can help guide production methods so as to reduce their environmental impacts. But the choices are not always clearcut.