Influence of Floral Origin and Storage Conditions on Physicochemical Properties of Libyan Honeys

Aim: The effect of botanical origin and storage conditions on the quality of two Libyan monofloral honey samples (thyme and ziziphus honeys) were assessed during prolonged storage (12 months) at room temperature. Methodology: Physicochemical properties (moisture, viscosity, electrical conductivity, acidity pH, 5-(hydroxymethyl) furfural (HMF), diastase activity, sugars, and color) were monitored. Results: Generally, moisture, acidity, diastatic activity, and color values were significantly higher in thyme honey, whereas viscosity, electrical conductivity, pH, HMF, and sugars content were higher in ziziphus honeys. In comparison with the initial values, viscosity, acidity, and HMF values of all honey samples increased during storage. Storage period and containers did not affect the electrical conductivity and sucrose contents for the two honey types, which were below the stipulated limits. Moisture content, pH, diastatic activity, color (L*), fructose, and glucose content decreased during storage. Honey samples stored in opaque container showed significantly lower changes in all parameters during the storage period compared to those stored in transparent bottles. The results showed that both honey types stored for 12 months at room temperature could be considered safe for human consumption according to maintaining physicochemical parameters.

Assessment of diastatic, proteolytic and lipolytic activities of yellow and brown varieties of Cyperus esculentus (Tigernuts) extracts

Analyses of two varieties of Cyperus esculentus (tigernuts) showed that the 100-nutweight of the yellow variety (49.1 g) was higher than the brown variety (14.8 g). The percentage of moisture contents for the yellow and brown varieties were 13.50% and 5.78% respectively. Treatment of soluble starch with tigernut extracts showed that starch hydrolysis occurred. The time for diastatic activity (α- + β- + γ-amylase activities) to completely hydrolyse starch was generally longer than either α- or β-amylase activity at 50℃. Periods and temperatures for complete starch hydrolysis by α-, β- and γ-amylases were virtually the same in the two tigernut extracts. The shortest time for complete starch hydrolyses by diastatic activity occurred at 50℃ and 65℃ for both yellow and brown varieties respectively. Least period for starch hydrolysis by α-amylase activity in both varieties occurred at 50℃, while the least time for β-amylase and γ-amylase activities in both tigernut varieties occurred at 65℃. Quantitative determination of amylolytic enzymes of yellow tigernut extract (TNE) on ‘dry basis’ showed that diastatic activity (183.6º) > α-amylase activity (167.3º) > β-amylase activity (119.8º) > γ-amylase activity (47.5º). Similarly, brown TNE amylolytic enzymes on ‘dry basis’ showed that diastatic activity (175.8º) > α-amylase activity (140.8º) > β-amylase activity (94.9º) > γ-amylase activity (49.6º). The α-amylase activity in yellow tigernut variety was 1.4-fold that of βamylase activity but about 1.5-fold in brown variety. However, α-amylase activity (dry basis) was about 3.5-fold that of γ-amylase in yellow variety but 2.8-fold in the brown variety. Extracts from both tigernut varieties also showed proteolytic and lipolytic activities at about 30℃. Evidently, tigernuts contain various endogenous hydrolytic enzymes and the sweetness of tigernut is invariably due to sugars produced from amylase hydrolysis of innate starch.

Understanding the chapati making attributes of the Indian wheats – I: The physico-chemical basis

The research project was largely built around the tall traditional cultivars of the pre-dwarfing era, which were known to excel for chapati quality. These included C 306, C 518 and C 273. The few cultivars that had emanated from crosses of these superior chapati quality wheats with dwarf wheats formed another important component of this set and included WG 357, PBW 175, PBW 154, PBW 226, Lok 1 among others. Asecond set of materials, three backcross recombinant populations (BC1F5 generation) derived from C 273/PBW 343//PBW 343 (70 lines), C 306/PBW 534//PBW 534 (70 lines) and C 518/PBW 343//PBW 343 (80 lines) were also studied to arrive at some conclusion. Various physico-chemical characters(Grain appearance score,Grain hardness,Test weight,1000-grain weight,Yellow berry,Moisture content,Protein content,Gluten content, Gluten index, Sedimentation value, Phenol Test, Carotenoids, Sugar content, Diastatic activity, Falling Number) and chapati-makingscores were evaluated. Grain hardness seems to have a clear role in chapati quality with a correlation coefficient of 0.34, 0.35 and 0.17 observed in different recombinant populations.More consistent correlation was found for grain appearance ranging from 0.26 to 0.36 in the populations.Consistent high positive correlations have showed up for diastase activity, which ranged from 0.32 to 0.46.This consistent behaviour is a strong evidence for the role of this trait in chapati making quality.Diastase activity emerges as a more consistent and stronger contributor to chapati making quality. Phenol score may not serve as a suitable indicator of chapati quality.

Physicochemical characteristics and sensory profile of honey samples from stingless bees (Apidae: Meliponinae) submitted to a dehumidification process

This study was conducted to evaluate the effect of a dehumidification process on the physicochemical and sensory characteristics of stingless-bee honey. Melipona scutellaris and M. quadrifasciata honey samples were submitted to a dehumidification process and to physicochemical (reducing sugars, apparent sucrose, moisture, diastatic activity, hydroxymethylfurfural, ash, pH, acidity, and electric conductivity) and sensory evaluations (fluidity, color, aroma, crystallization,flavor,and acceptability). The results indicated that the dehumidification process does not interfere with honey quality and acceptability.