CHAPTER 3 METHODOLOGY
3.1 To study the possibility to produce creamed honey product from various types
3.1.2 To study the effect of moisture and glucose content to the honey
Only honey types which presented in slow and rapid crystallization will study in this part. There were two methods for stimulating in rapidly crystallization, one is to increase the glucose content by adding the glucose powder and second is decrease the water content by dehydration method.
Figure 12 Flow chart of overall research methodology
1) To study the dehydration method
The glucose/water ratio should higher than 2.16, the honey will present in rapid crystallization (Bhandari et al., 1999). Therefore, if the water content decrease, the glucose/water ratio will increase and change the crystallization behavior of honey. One method to reduce the water content in honey is the dehydration process by heating in low temperature for preserve the honey quality. Because the heating above 50C will affects the quality and causes protein denaturation and deactivation of several enzymes which are mainly responsible for its functional behavior (Janghu et al., 2017). That is why minimal processing techniques or heating treatment in low temperature is very important and study for applying in honey dehydration.
Four levels of dehydration temperature were including 35, 45, 55 and 65C.
The dehydration by using vacuum far-infrared dryer were carried out under the conditions: pressures in drying chamber (5 kPa) at temperature at 40C (Intipunya and Metanee, 2012; Kunjet et al., 2017) and will compare with the dehydration by hot air oven. The dehydration process will monitor until the unacceptable of honey appearance presented. Longan honey is the non-granulating honey which is suitable to study in this part. As mention above that the G/W ratio will increase by the reducing of moisture content in honey, so longan honey will use to study in the dehydration method. If the raw material is the honey which is easy to crystallize, it will easy to control the creamed honey process. The longan honey samples which fixed the initial glucose content and set namely in dehydrated honey and non- dehydrated honey). The moisture content was measured according to the Harmonized Methods of the International Honey Commission (Bogdanov, 2009), and second, the samples was determined the moisture content by the method described by the AOAC (Horwitz et al., 1970). Multiple comparison of moisture means was conducted by Duncan’s multiple-range test (Mossel et al., 2000) and the kinetic of dehydration process was analyzed with the G/W ratio variation.
Regarding to the quality of granulated honey or creamed honey, from the stand-point of human taste, depends on size of crystals, and honey with large coarse crystallization is inferior to that with small crystals. Moreover, the small crystals was obtained from only rapid or fast crystallization and glucose content should present to about 34% which is readily crystallized and forms the solid phase of creamed honey (Dyce, 1931a). Thus, this study aims to investigate the possibility to increase the crystallization rate by adding of glucose powder with sunflower and longan honey. Two honey samples were analyze chemical properties including moisture, glucose, water activity and pH values according to the Harmonized Methods of the International Honey Commission (Bogdanov, 2009), and AOAC (Horwitz et al., 1970).
Samples were heated at 50C to eliminate natural crystals and osmotolerant/osmophilic yeasts by using a water bath (Tosi et al., 2004). Heated honey samples were kept at room temperature before seeding addition. Glucose monohydrous powder (C6H12O6, Merck, Germany) was employed as seed (Elhamid and Abou-Shaara, 2016). Glucose powder was added in both honey types (40 g of liquid honey), but none was added to the control sample, as shown in Figure 13.
Samples were manually stirred with a spatula at room temperature for about 10 min to thoroughly mix between the glucose powder and liquid honey (Dettori et al., 2018). Samples were then stored at a chilling temperature (10 - 15C) to allow the crystallization process. The temperature in the refrigerator was checked daily during the experiment. Crystallized honey samples were periodically measured for absorbance at different sampling periods and visual observation was conducted to check the overall appearance. If there were crystals occurring throughout the honey sample, it was deemed full crystallization.
(A) Liquid longan honey and glucose powder adding method
(B) longan honey with glucose addition
(C) sunflower honey with glucose addition Figure 13 Glucose powder addition method
The moisture content was determined following a refractive index method (Bogdanov, 2009) by measuring the refractive index of honey with a digital Abbe refractometer (KRUSS, Germany). Three samples from each trial were analyzed for determination of moisture, and the average moisture content was reported. Sugar content (fructose, glucose, sucrose, and maltose) was determined by HPLC, according to Official method 977.20 (AOAC, 2000). Water activity was measured by using a water activity meter (AQUA Lab 3TE, USA). Measured of each sample was duplicated, and the average water activity was calculated.
into four groups, then glucose monohydrous powder (C6H12O6.H2O) was used as seed.
Glucose powder with % of 1.0, 1.5, 2.0 and 2.5 (w/w) was added to the four groups and 0% (w/w) was control by not added glucose powder. The time needed till full crystallization was recorded for each treatment. After full crystallization, samples of crystallized honey of each group were subjected to measure the color.
The color was measured by using Spectrophotometer (HunterLab Miniscan XE plus, Germany) and reported in value of L*, a* and b*. Calibration of instrument was done with a black and white standard tile before each set of measurements. The L* colour value presented the degree of brightness or whiteness of the sample, while a* and
b* colour values indicated the degree of redness and yellowness, respectively. Three measurements were done in each sample. All parameters were used to calculate the hue angle (ho) and Whiteness Index (WI) (Briones and Aguilera, 2005) as following Eq. (2) – (5).
The absorbance measured at 660 nm for monitoring the crystallization kinetic during storage.Honey samples were poured into a cuvette about 1 cm with a path- length. Some trials with many types of liquid honey were taken to scan for wavelength in a range between 200 – 700 nm and presented the smooth curve in range between 600-700 nm. Therefore, the absorbance was measured at 660 nm at room temperature by spectrophotometer (Model SPECTRO SC, U.S.A.) as following trials and literature review (Conforti et al., 2006; Costa et al., 2015; Lupano, 1997).
The experiment was designed as completely randomized design (CRD) and analysis of Variance (ANOVA) was performed and means of measured parameters were compared using Duncan Multiple range test at 5% level of significance (Elhamid and Abou-Shaara, 2016).