foods Article Effect of the Roasting Conditions on the Physicochemical, Quality and Sensory Attributes of Coffee-Like Powder and Brew from Defatted Palm Date Seeds Mohammad Fikry 1,2,* , Yus Aniza Yusof 1,3,*, Alhussein M. Al-Awaadh 4, Russly Abdul Rahman 5, Nyuk Ling Chin 1, Esraa Mousa 6 and Lee Sin Chang 7 1 Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia; [email protected] 2 Department of Biosystems and Agricultural Engineering, Faculty of Agriculture, Benha University,13736 Moshtohor, Toukh, Qalyoubia Governorate, Egypt 3 Laboratory of Halal Services, Halal Products Research Institute, Universiti Putra Malaysia, 43400 Selangor, Malaysia 4 Department of Agricultural Engineering, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia; [email protected] 5 Department of Food Technology, Faculty of Food Science & Technology, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia; [email protected] 6 Department of special food and nutrition, Food Technology Research Institute, Agricultural research center, Giza, Egypt; [email protected] 7 Department of Food Science, Faculty of Food Science & Technology, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia; [email protected] * Correspondence: [email protected] (M.F.); [email protected] (Y.A.Y.); Tel.: 006-03-8947-1841 (Y.A.Y.) Received: 30 December 2018; Accepted: 23 January 2019; Published: 6 February 2019 Abstract: Developing a bioactive brew is a novel track for revalorization of palm date byproducts. The effect of roasting temperature (160, 180 and 200 ◦C ) and roasting time (10, 20 and 30 min) on the hardness of the roasted date seeds, moisture content of the defatted roasted date seed powder (DRDSP), bulk density of the DRDSP, color parameters of DRDSP, quality attributes (extraction yield, pH and browning index), the chemical properties (antioxidants and total phenolic content) and the sensory attributes (color, aroma, taste and overall preference) of the brew prepared from DRDSP was studied. The physicochemical, quality, and sensory attributes were found to be significantly influenced by the roasting temperature and time. Additionally, the models proposed could satisfactorily describe the changes in the different properties during the roasting process. The optimum conditions of the roasting process obtained using the superimposed contour plot were 199.9 ◦C and 21.5 min. In the longer term, the results of this study would be beneficial for the manufacturers of the date seeds powder and brew. Keywords: roasting; palm date seeds; optimization; antioxidants; total phenolic content; coffee-like brew 1. Introduction Palm dates (Phoenix dactylifera L.) are considered to be a nutritional component of the diet and a staple food source in most Middle Eastern and North African regions. Dates can be consumed either in a fresh form or as a derivative product, such as date-syrup, date-honey, date-jam, date-vinegar, and date-paste. In 2016, the global production of palm date fruits was approximately 8.5 million tons [1]. It Foods 2019, 8, 61; doi:10.3390/foods8020061 www.mdpi.com/journal/foods Foods 2019, 8, x FOR PEER REVIEW 2 of 20 1. Introduction Palm dates (Phoenix dactylifera L.) are considered to be a nutritional component of the diet and a stapleFoods 2019 food, 8, 61source in most Middle Eastern and North African regions. Dates can be consumed either2 of 19 in a fresh form or as a derivative product, such as date-syrup, date-honey, date-jam, date-vinegar, and date-paste. In 2016, the global production of palm date fruits was approximately 8.5 million tons [1].was It reported was reported that the that average the average percentage percentage of the dateof the seeds date isseeds approximately is approximately 10% of 10% the totalof the weight total weightof the whole of the datewhole fruit date in fruit the tamrin the “fully tamr ripening”“fully ripening” stage [ 2stage]. Date [2]. seeds Date areseeds generated are generated during during direct directconsumption consumption or from or thefrom date the processingdate processing industries industries [3] (Figure [3] (Figure1). Presently, 1). Presently, these these byproducts byproducts are aregenerally generally discarded discarded leading leading to to environmental environmental problems, problems, or or instead, instead, areare utilizedutilized as animal animal fo fodder.dder. The lack lack of of uses uses for for this this by- by-productproduct for forhuman human food food constitutes constitutes a real a economic real economic loss since loss it since is rich it in is dietaryrich in dietaryfiber, phenolic fiber, phenolic compounds compounds and antioxidants, and antioxidants, which which can also can alsobe extracted be extracted and andused used as therapeuticas therapeutic components components [4]. [ 4It]. has It has been been reported reported that that dietary dietary fiber fiber has has important important therapeutic implicationsimplications for for certain certain conditions, conditions, such such as as diabetes, diabetes, hyperlipidaemia, hyperlipidaemia, and and obesity, obesity, and and may may provide provide aa protectiveprotective effecteffect against against hypertension, hypertension, coronary coronary heart heart disease, disease, high cholesterol,high cholesterol, colorectal colorectal and prostate and prostatecancers, andcancer intestinals, and intestinal disorders [disorders5]. Additionally, [5]. Additionally, antioxidants antioxidants and phenolic and compounds phenolic couldcompounds protect couldagainst protect major against chronic major diseases, chronic such diseases, as different such types as different of cancer, types cardiovascular of cancer, cardiovascular disease, coronary disease, heart coronarydisease, atherosclerosis heart disease, andatherosclerosis neurological and problems, neurological as well problems, as aiding a ins well treating as aiding renal stones,in treating bronchial renal stones,asthma, bronchial coughing, asthma, hyperactivity coughing, and poorhyperactivity memory, and helping poor to memory, reduce blood helping pressure, to reduce relaxing blood the pressure,intestinal relaxing and uterine the musculature,intestinal and growing uterine bodymusculature, protein by growing reducing body fat, normalizingprotein by reducing blood sugar, fat, normalizingand comforting blood the sugar, pancreas and [ 6comf]. orting the pancreas [6]. DueDue toto thethe foregoing foregoing mentioned mentioned benefits, benefits, several several potential potential uses ofuses date of seeds date have seeds been have identified been identifiedand reported and in reported the literature. in theThese literature. included These date included seed powder date seed as an powder ingredient as an in foodingredient products in food such productsas ground such beef as [7 ],ground bakery beef products [7], bakery [8,9], chocolateproducts [[8,9],10] and chocolate non-caffeinated [10] and drinksnon-caffeinated [11,12]. Virtually, drinks [11,12].roasted dateVirtually seed powder, roasted is date being seed used powder in the Arabian is being region, used includingin the Arabian the Kingdom region, of including Saudi Arabia the Kingdom(KSA) and of the Saudi United Arabia Arab Emirates(KSA) and (UAE), the United for preparation Arab Emirates of an alternative (UAE), for brew preparation to coffee [of12 ,13an] alternativeto avoid negative brew to health coffee impacts, [12,13] to such avoid as raisingnegative blood health pressure, impacts, panic such attacks, as raising hypertension, blood pressure, gout, panicinsomnia, attacks, indigestion, hypertension, infertility, gout, and insomnia, inhibition ofindigestion, collagen creation infertility, in the and skin, inhibition as well as of depression collagen creationand anxiety in the symptoms skin, as well resulting as depression from the and high anxiety content symptoms of caffeine resulting in coffee from (20–40%) the high [11 content]. It was of caffeinereported in that coffee a brew (20– made40%) from[11]. It roasted was report palmed date that seeds a brew can bemade safely from consumed roasted palm and served date seeds to people can bewho safely are sensitiveconsumed to caffeineand served and to prefer people to enjoy who theare characteristicsensitive to caffeine flavor and and aroma prefer of to caffeine-free enjoy the characteristiccoffee without flavor the adverse and effectsaroma [ 14of–16 caffeine]. Interestingly,-free coffee roasted without palm date the seedsadverse have effects similar aromatic[14–16]. Interestingly,compounds (alcoholsroasted palm and aldehydes)date seeds have that existsimilar in aromatic Arabica coffeecompounds brews (alcohols [17,18] and, and importantly,aldehydes) thatare caffeineexist in Arabica free [12, 13coffee]. brews [17,18] and, importantly, are caffeine free [12,13]. FigureFigure 1. 1. PalmPalm date date waste wastess resulting resulting from from different different processes. The roasting process is considered one of the production stages of the date seed brew due to its advantages such as (i) increasing the efficiency of post-processing, (ii) improving food quality, Foods 2019, 8, 61 3 of 19 and (iii) prolonging the shelf life of foods. Importantly, both temperature and time are considered the most important conditions of the roasting process. Mendes, et al. [19] stated that several factors might affect the required optimal roasting conditions, such as the required roasting level, the type of