Ali Sahli

Does the spicing step affect the quality and drying behaviour of traditional kaddid, a Tunisian cured meat?

BACKGROUND The effects of spicing on the physicochemical and microbial characteristics and drying behaviour of kaddid, a Tunisian dry-cured meat, were studied. In addition, the quality characteristics of traditional sun-dried kaddid and processed convective-dried kaddid were compared. RESULTS Spicing had no significant effect on the pH and water activity of brined beef meat at 21% (w/w), but it reduced the product water and salt contents. Effects of spicing on brined meat microbial flora were the appearance of sulfito-reducer bacteria, an increase in total mesophilic aerobic flora (+15%) and staphylococci (+26%) and a decrease in faecal coliforms (-23%). The salted beef meat sorption behaviour was affected by spicing. Besides, spicing increased the kaddid drying rate, allowing a significant decrease in the drying process time (-33%). Traditional and processed kaddid presented comparable microbial characteristics. Both drying methods led to a reduction in the number of total mesophilic aerobic flora in unspiced and spiced kaddid and of faecal coliforms in spiced kaddid. CONCLUSION The study showed that spicing, as a step in kaddid meat processing to enhance the final product flavour, caused changes in the salted meat physicochemical and microbial characteristics and accelerated the drying rate. Convective drying at 30 °C is recommended to produce kaddid having the same characteristics as the traditional product.

Effect of Plant Originated Coagulants and Chymosin on Ovine Milk Coagulation

The coagulation of ewes milk was studied by using plant source coagulants namely the artichoke, Cynara scolymus L. cv. Blanca, and latex from the fig tree (Ficus carica L.). A turbidimetric method was used to evaluate and compare the coagulation properties of the novel coagulants with chymosin treated samples. Syneresis capacity and sensory evaluation of resultant cheese samples were studied and it was found that both cynara and chymosin produced sigmoidal increase in turbidity to the milk with three distinct phases. The coagulation kinetics was affected substantially by both coagulants. Plant coagulant induced shorter gelation time compared to chymosin however required longer time for restructuration (end of coagulation). The coagulum obtained with the latex of Ficus carica had a higher yield, owing to its high water retention capacity. With the exception of color, the overall sensory attributes did not show significant differences among coagulants.

Effect of Milk Fat Substitution of Rennet Milk Induced Coagulation on Physico-Chemical Properties

The objective of this paper was to study the effect of milk fat substitution by (W1/O/W2) multiple emulsions based on olive oil in comparison with full and low-fat milks on milk behavior during rennet coagulation. Therefore, based on the turbidimetric and conductivimetric methods, a follow up of enzymatic coagulation is realized. Drainage of renneted gels was followed by syneresis study and cheese yield. The comparison between the coagulation aptitude of low fat milk and milk-olive oil emulsion showed that the hydrolysis phase extended up to 35 minutes for full fat milk and up to 38 minutes for milk-olive oil emulsion. The transition phase solid/gel was shorter in the case of the whole milk. The reticulation phase was shorter in the case of milk-olive oil emulsion. The milk conductivity depended on the milk richness in fat content. Milk-olive oil emulsion showed the lowest cheese-making yield compared to its full and low-fat counterpart.

Genetic variation of salt-stressed durum wheat (Triticum turgidum subsp. durum Desf.) genotypes under field conditions and gynogenetic capacity

Agriculture has new challenges against the climate change: the preservation of genetic resources and the rapid creation of new varieties better adapted to abiotic stress, specially salinity. In this context, the agronomic performance of 25 durum wheat (Triticum turgidum subsp. durum Desf.) genotypes (nineteen landraces and six improved varieties), cultivated in two semi-arid regions in the center area of Tunisia, were assessed. These sites (Echbika, 2.2 g l−1; Barrouta, 4.2 g l−1) differ by their degree of salinity of the water irrigation. The results showed that most of the agronomic traits (e.g. spike per meter square, thousand kernels weight and grain yield) were reduced by salinity. Durum wheat landraces, Mahmoudi and Hmira, and improved varieties, Maali and Om Rabia showed the widest adaptability to different quality of irrigation water. Genotypes including Jneh Kotifa and Arbi were estimated as stable genotypes under adverse conditions. Thereafter, salt-tolerant (Hmira and Jneh Khotifa) and the most cultivated high-yielding (Karim, Razzak and Khiar) genotypes were tested for their gynogenetic ability to obtain haploids and doubled haploid lines. Genotypes with good induction capacity had not necessarily a good capacity of regeneration of haploid plantlets. In our conditions, Hmira and Khiar exhibited the best gynogenetic ability (3.1% and 2.9% of haploid plantlets, respectively).

Agricultural fields classification in semi-arid central Tunisia using SPOT 7 image

This paper reports on classification methods applied and tested for land use classification in a semi-arid environment. Our study, conducted on two irrigated sites located in the Kairouan region, the largest irrigated region in Tunisia, compared Support Vector Machine (SVM) and Maximum Likelihood classification of SPOT-7 data. To produce a per-field classification a Mean-Shift Segmentation has been performed on the pansharpened SPOT-7 images. A field survey has been conducted. Accuracy assessment was done to evaluate the performance of the proposed using collect ground truth data on land use and extend of all the agricultural fields within the study areas obtained through filed survey.