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A new original application for a polyacrylic film based on the monomers 2-(dimethylamino)ethyl methacrylate (NNDA), 2-hydroxyethyl acrylate (2HEA) and methylmethacrylate (MMA) as a starch azure container has been set up for a simple determination of honey diastase activity. The proposed method is based on the correlation of reducing sugars generated during the enzymatic process with the Schade reference assay. The polyacrylic film is charged with starch azure acting as a container for this substance; thus, the starch does not interfere in the measurement of reducing sugars, so that the diastase activity is easily calculated. The method has been contrasted with Schade method, showing good correlation and differences under 0.4% between methods in some honey samples. The polyacrylic film has great potential for the routine honey diastase activity assessment in small laboratories, dramatically reducing analysis time and cost., FEDER (Fondo Europeo de Desarrollo Regional), and both the Spanish Ministerio de Economía, Industria y Competitividad (MAT2017-84501-R) and the Consejería de Educación—Junta de Castilla y León (BU306P18 and BU041G18)

The activities of enzymes are the basis of evaluating the quality of honey. Beekeepers usually use concentrators to process natural honey into concentrated honey by concentrating it under high temperatures. Active enzymes are very sensitive to high temperatures and will lose their activity when they exceed a certain temperature. The objective of this work is to study the kinetic mechanism of the temperature effect on diastase activity and to develop a nondestructive approach for quick determination of the diastase activity of honey through a heating process based on visible and near-infrared (Vis/NIR) spectroscopy. A total of 110 samples, including three species of botanical origin, were used for this study. To explore the kinetic mechanism of diastase activity under high temperatures, the honey of three kinds of botanical origins were processed with thermal treatment to obtain a variety of diastase activity. Diastase activity represented with diastase number (DN) was measured according to the national standard method. The results showed that the diastase activity decreased with the increase of temperature and heating time, and the sensitivity of acacia and longan to temperature was higher than linen. The optimum temperature for production and processing is 60 &deg, C. Unsupervised clustering analysis was adopted to detect spectral characteristics of these honeys, indicating that different botanical origins of honeys can be distinguished in principal component spaces. Partial least squares (PLS) and least squares-support vector machine (LS-SVM) algorithms were applied to develop quantitative relationships between Vis/NIR spectroscopy and diastase activity. The best result was obtained through Gaussian filter smoothing-standard normal variate (GF-SNV) pretreatment and the LS-SVM model, known as GF-SNV-LS-SVM, with a determination coefficient (R2) of prediction of 0.8872, and root mean square error (RMSE) of prediction of 0.2129. The overall results of this paper showed that the diastase activity of honey can be determined quickly and non-destructively with Vis/NIR spectral methods, which can be used to detect DN in the process of honey production and processing, and to maximize the nutrient content of honey.

Honey is used for centuries both as nutrient and in medicine, being an exhaustless source of benefic factors for health and also for different biotechnological processes. This is a complex matrix which possesses antioxidant and antimicrobial properties due to its peroxidic activity and bioactive compounds. A fully validated approach for the determination of sugars, hydroxymethylfurfural content and diastase activity in honey samples were presented in accordance with the official methods from the International Honey Commission. Spectrophotometric method was used for diastazic activity determination and chromatographic determinations for HMF content (photodiode array detection) and sugars (refractive index detection). The limits of detection and quantification were calculated. Accuracy, precision and uncertainty were determined in the spectrophotometric and chromatographic techniques using the certified reference material. Diastase activity, sucrose content and hydroxymethylfurfural (HMF) content were easily differentiated and these parameters were used for indication of a possible adulteration of the honey. The present study confirms that, in order to have an authentic honey sample, diastazic activity must be above 8 DN (diastazic number) and HMF content less than 40 mg/kg. Sugar spectrum is different for every honey type. Consequently, physico-chemical analysis should be combined for the determination of authentic honey and proper labeling.

This research intends to reveal the effects of different storage temperatures on the HMF amounts and diastase activities of strained flower honey and honeydew honey samples produced by different companies in Turkey. In this context, the initial HMF values and diastase activities of the strained flower honey and honeydew honey samples belonging to five different companies, collected at the date of filling, were examined with defined quality criteria (moisture, sugar, pH, acidity, electrical conductivity and ash). Samples were stored at certain temperatures (10±2 °C, 22±2 °C, 35±2 °C), and were analyzed at the end of each of the threemonth periods (3rd, 6th, 9th and 12th months) regarding HMF and diastase activity. According to the results, average HMF values of the flower honey and honeydew honey samples stored at 10±2 °C and 22±2 °C for one year did not exceed 40 mg/kg, which is given as the limit HMF value in the Turkish Food Codex (TFC) Directive on honey, while it rapidly increased in the samples stored at 35±2 °C, and was determined to be over 40 mg/kg as of 6th month onwards. In addition, average diastase activities of the samples at 10±2 °C and 22±2 °C did not drop below the limit value of 8 in TFC, though it was determined to be below 8 as of 6th month onwards, for the flower honey stored at 35±2 °C. To conclude, decrease in diastase activity shortens the shelf lives set by the firms. By providing proper production and storage conditions, all quality criteria should be ensured to remain consistent with the TFC Directive on honey, Bu araştırmada Türkiye’de farklı firmalarca üretilen süzme çiçek ve salgı balı örneklerinin HMF miktarı ve diastaz aktivitesi üzerine farklı muhafaza sıcaklıklarının etkisinin ortaya konulması amaçlandı. Bu kapsamda fabrikalardan dolum tarihlerinde alınarak kalite kriterleri (nem, şeker, pH, asitlik, elektriksel iletkenlik, kül) belirlenen beş farklı firmaya ait süzme çiçek ve çam balı örneklerinin başlangıç HMF değeri ve diastaz aktiviteleri saptandı. Örnekler, belirli sıcaklıklarda (10±2 °C, 22±2 °C, 35±2 °C) muhafaza edilerek üç aylık periyotlar (3, 6, 9 ve 12. ay) sonunda HMF ve diastaz aktivitesi yönünden analiz edildi. Elde edilen bulgulara göre, bir yıl boyunca 10±2 °C ve 22±2 °C’de muhafaza edilen çiçek ve salgı balı örneklerinin ortalama HMF değerleri Türk Gıda Kodeksi (TGK) Bal Tebliği’nde sınır HMF değeri olarak belirtilen 40 mg/kg’ı aşmazken, 35±2 °C’de muhafaza edilen örneklerde hızla artarak 6. aydan itibaren 40 mg/kg’ın üzerinde saptandı. Ayrıca örneklerin 10±2 °C ve 22±2 °C’deki ortalama diastaz aktiviteleri TGK Bal Tebliği’nce belirtilen sınır değer olan 8’in altına düşmezken 35±2 °C’de muhafaza edilen çiçek balları için bu değer 6. aydan itibaren 8’in altında saptandı. Sonuç olarak tüketime sunulan süzme ballarda, gerek üretim sırasında uygulanan ısı işlemi, gerekse muhafaza sıcaklığına bağlı olarak artan HMF değeri ile azalan diastaz aktivitesi firmalarca belirlenen raf ömrünü kısaltmaktadır. Bala ait uygun üretim ve muhafaza koşulları sağlanarak, başta HMF ve diastaz olmak üzere tüm kalite kriterlerinin TGK Bal Tebliği’ne uygunluğu raf ömrünün sonuna kadar sağlanmalıdır

Rye (Secale cereale L.) is the most important cereal crop after wheat, rice and maize. A substantial part of the rye yield is used for bread making, especially in European countries. There have been numerous studies on grain enrichment with selenium (Se), as it is known that selenium is a fundamental trace element essential for human health and in the form of selenoproteins plays key structural and enzymic roles. The main aim of this study was to investigate the effect of different selenium concentrations on quality indices of rye malt - the content of malt extract, diastase activity, selenium and total phenol content in malt. Rye grain of 95% viability was soaked and germinated at temperature +6 ± 2 °C for three days +18 ± 2 °C, using sodium selenate Na2SeO4 solutions (Se concentration 3 mg l-1, 5 mg l-1, 10 mg l-1), and dried in an oven for 24 hours at temperature +70 - 112 °C. Germination of grain with deionised water served as a control. The obtained results showed that an increase of selenium concentration caused increase of malt extract concentration (from 74 to 80%), selenium concentration (from 0.0139 to 0.3251 mg kg-1) and total phenol concentration (from 3.13 to 3.63 mg GAE g-1 DW) in rye malt, while diastase activity decreased from 330 to 216.